Chemical change (CC): one or more chemicals are changed into new substances that have different chemical compositions and properties.
Chemical property (CP): characteristic or behaviour of a substance that is only discernible or measurably altered by a chemical reaction or change.
Physical change (PC): process that modifies a substance's form, state, or appearance while maintaining its chemical composition.
A physical property (PP) : characteristic or behaviour of a substance that can be seen or measured without altering the chemical makeup of the substance.
1. Sublimation - Physical change (PC)
2. Silver tarnishing - Chemical change (CC)
3. Heat conductivity - Physical property (PP)
4. Magnetizing steel - Physical change (PC)
5. Shortening melting - Physical change (PC)
6. Exploding dynamite - Chemical change (CC)
7. Length of metal object - Physical property (PP)
8. Brittleness - Physical property (PP)
9. Combustible - Chemical property (CP)
10. Baking bread - Chemical change (CC)
11. Milk souring - Chemical change (CC)
12. Water freezing - Physical change (PC)
13. Wood burning - Chemical change (CC)
14. Acid resistance - Chemical property (CP)
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rust can be prevented by:select the correct answer below:
a.submerging the metallic
b.iron in waterapplying
c.paint to the iron magnetizing
d.the ironnone of the above
Rust can be prevented by applying paint to the iron. The correct answer is option c.
Rust refers to the reddish-brown iron oxide that forms on the surface of iron, particularly when exposed to moisture. Rust is a form of corrosion, which is a chemical reaction that occurs when metal surfaces come into touch with water, air, or other chemicals.
The prevention of rustThe following methods can be used to avoid rust:
Painting: Paint serves as a barrier between the surface of the metal and the environment, preventing corrosion or rust formation.
Galvanization: In this procedure, a protective layer of zinc is added to the metal surface, forming a barrier that prevents rust from forming.
Polishing: Polishing metal surfaces ensures that the surface is smooth, devoid of any rough spots that can act as rust initiation sites.
Therefore, the correct answer is option c. Paint to the iron
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the heat of fusion of water is 79.5 cal/g. this means 79.5 cal of energy are required to:
The heat of fusion of water is 79.5 cal /g. This means 79.5 cal of energy is required to melt one gram of ice at its melting point. Therefore, the answer is "melt one gram of ice at its melting point.
"What is the heat of fusion? The amount of heat required to transform a substance from its solid state to its liquid state without raising the temperature is known as the heat of fusion.
The heat of fusion of water is the quantity of energy required to melt a specific amount of ice at its melting point. The heat of fusion of water is 79.5 cal/g.
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QUESTION TWO: MEDICAL ISOTOPES lodine 131, written ¹1, is a radioactive isotope used in medicine. lodine 131 decays to Xenon (Xe) by emitting a beta particle. a. (i) What is a beta particle? (ii) Com
Iodine-131 (131 I, I-131) is a radioactive isotope used in medicine. It decays to Xenon (Xe) by emitting a beta particle, and its count rate decreases by half every 5.45 minutes, with a half-life of approximately 327 seconds.
a. (i) A beta particle is a high-energy electron or positron that is emitted from the nucleus during radioactive decay. It is denoted by the symbol β.
(ii) Alpha particles are positively charged and consist of two protons and two neutrons (helium nucleus), while beta particles are negatively charged electrons or positively charged positrons. Beta particles have a higher penetration ability compared to alpha particles because they have a smaller mass and carry less charge. This allows them to travel further and penetrate deeper into materials before being stopped or absorbed.
b. (i) Isotopes of iodine have the same number of protons, which defines the element. Iodine-131 and other iodine isotopes differ in the number of neutrons in their nuclei.
Same: Isotopes of iodine have the same number of protons (53) in their nuclei, which defines them as iodine.
Different: Iodine-131 has a different number of neutrons (78) compared to other isotopes of iodine, which have different neutron numbers.
c. To calculate the count rate of the radiation produced by the radioactive sample, we subtract the background count rate from the total count rate.
(i) Count rate of radiation from the sample = Total count rate - Background count rate
Given:
Background count rate = 15 counts per second
Total count rate at the start = 168 counts per second
Total count rate after 7 minutes = 53 counts per second
Count rate of radiation from the sample at the start = 168 - 15 = 153 counts per second
Count rate of radiation from the sample after 7 minutes = 53 - 15 = 38 counts per second
(ii) To calculate the half-life of the radioactive sample, we can use the formula:
[tex]\begin{equation}t_{1/2} = \frac{t \log(2)}{\log(N_0/N_t)}[/tex]
where t1/2 is the half-life, t is the time interval (7 minutes = 420 seconds), N0 is the initial count rate, and [tex]N_t[/tex] is the count rate after the given time interval.
Using the given data:
[tex]\[t_{1/2} = \frac{420 \log(2)}{\log(168/53)}\][/tex]
t1/2 ≈ 327 seconds or 5.45 minutes
Therefore, the half-life of the radioactive sample is approximately 327 seconds or 5.45 minutes.
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Complete question :
QUESTION TWO: MEDICAL ISOTOPES lodine 131, written ¹1, is a radioactive isotope used in medicine. lodine 131 decays to Xenon (Xe) by emitting a beta particle. a. (i) What is a beta particle? - (ii) Compare the charges of alpha and beta particles and explain why beta particles have a higher penetration ability. b. (i) Describe how the nuclei of isotopes of iodine are the same as iodine-131, and how they are different. Same: Different: (i) Calculate the number of neutrons in iodine 131. The low-level radiation in our environment is called the background radiation. Sarah measures the background radiation and finds that it is 15 counts per second. This is the same, day after day. Sarah now measures the radiation from a radioactive sample. The count rate she measures includes background radiation. When she starts her measurement the count rate from the sample, including background radiation, is 168 counts per second. After 7 minutes this count rate has fallen to 53 counts per second. c. Explain how the count rate of the radiation produced by the radioactive sample can be calculated from the above information. (i) Calculate the count rate of the radiation produced by the radioactive sample. Time Count rate from the sample only (counts per second) At the start After 7 min (ii) Use your data from the table to calculate the half-life of the radioactive sample.
which of the following dietary components cannot be used to synthesize and store glycogen?
The dietary components cannot be used to element synthesize and store glycogen is Lipids. Glycogen synthesis is mainly driven by insulin, which is a hormone that is secreted by the pancreas.
Glycogen is a complex carbohydrate that is used to store glucose in animals. Glycogen synthesis is mainly driven by insulin, which is a hormone that is secreted by the pancreas. When insulin levels are high, glucose is converted into glycogen and stored in the liver and muscle cells.Lipids cannot be used to synthesize and store glycogen. Lipids are a type of macronutrient that is used to store energy in the form of fat.
Glycogen is a complex carbohydrate that is used to store glucose in animals. Glycogen synthesis is mainly driven by insulin, which is a hormone that is secreted by the pancreas. When insulin levels are high, glucose is converted into glycogen and stored in the liver and muscle cells.Lipids cannot be used to synthesize and store glycogen. Lipids are synthesized from glycerol and fatty acids, which are derived from carbohydrates and proteins.
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This problem deals with a battery for the overall reaction Zn(s) 2 Ag (aq) The cell is constructed as follows: The silver metal electrode weighs 10.0 g The zinc metal electrode weighs 10.0 g. water, The volume The left compartment contains 10.0 g of silver(I) sullate dissolved in of this solution is 100.0 mL volume of The right compartment contains 10.0 g of zinc sulfate ved in water. The his solution is 100.0 mL A current of96.5 Amps has passed through the battery for 10 sec. (a) What is the concentration in molM of silver ion in the left compartment after this charge has passed? after this (b) What is the concentration in mollL of zinc ion in the right compartment charge has passed? (e) What is the mass of the zine electrode after this charge has passed? The battery continues to run until it is completely dead. (d) How many moles of electrons (total) have passed? (e) What is the concentration in Lof silver ion in the left compartment after this charge has passed?
The concentration in L of silver ion in the left compartment after the charge has passed is 0.002675 M.
What is the cell reaction for the given problem?
The given problem deals with a battery for the overall reaction Zn(s) 2 Ag(aq). This reaction can be divided into two half-reactions: Zn → Zn2+ + 2e− (oxidation)Ag+ + e− → Ag (reduction)To form the overall cell reaction, we add these two half-reactions and eliminate electrons on both sides. So the overall cell reaction is:Zn + 2Ag+ → Zn2+ + 2Ag.
What is the initial moles of silver ion in the left compartment?
To find the concentration of silver ion in the left compartment, we first need to find the initial moles of silver ion in the left compartment. We are given that the left compartment contains 10.0 g of silver(I) sulfate, and the volume of this solution is 100.0 mL.
To find the concentration in L of silver ion in the left compartment after this charge has passed, we can express the concentration in mol/L in scientific notation: concentration of Ag+ = 0.74 M= 7.4 × 10⁻¹ M= 7.4 × 10⁻³ mol/L.
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Calculate the number of moles of excess reactant that will be left-over when 56.0g of CaCl2 reacts with 64.0g of Na2SO4: CaCl2+Na2SO4 -->CaSO4+2NaCl
56.0g of CaCl2 reacts with 64.0g of Na2SO4: CaCl2+Na2SO4 -->CaSO4+2NaCl. The balanced chemical equation for the given reaction is: CaCl2 + Na2SO4 → CaSO4 + 2NaCl.
The molar mass of CaCl2 is 111 g/mol. The molar mass of Na2SO4 is 142 g/mol. To find out the excess reactant, first, we have to calculate the moles of both reactants. Moles of CaCl2 = Mass / Molar mass = 56.0 / 111 = 0.5045 mol. Moles of Na2SO4 = Mass / Molar mass = 64.0 / 142 = 0.4507 mol. Now, we will determine the limiting reagent and the excess reagent. Limiting reagent is Na2SO4 because the number of moles is less as compared to CaCl2. So, Na2SO4 is the limiting reagent.
Excess reagent is CaCl2 because it is in excess of the amount required to react with Na2SO4. Moles of Na2SO4 reacted with CaCl2 = (Moles of CaCl2) x (Molar ratio of Na2SO4 to CaCl2) = 0.5045 mol x (1 mol Na2SO4 / 1 mol CaCl2) = 0.5045 mol. The number of moles of Na2SO4 that reacted completely with CaCl2 is 0.5045 mol. Now, we can find the number of moles of Na2SO4 left over. Excess moles of Na2SO4 = Total moles of Na2SO4 - moles of Na2SO4 reacted with CaCl2= 0.4507 - 0.5045= -0.0538 mol. So, the number of moles of excess reactant (Na2SO4) is -0.0538 mol.
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To increase solubility of a gas into a liquid the most, then A) neither pressure or temperature affects solubility. B) increase the temperature and lower the pressure. C) decrease the temperature and raise the pressure. D) increase the temperature and raise the pressure. E) decrease the temperature and lower the pressure.
The correct answer is option D, which is to increase the temperature and raise the pressure to increase solubility of a gas into a liquid the most. Solubility is the maximum quantity of a substance that can be dissolved in a particular solvent at a specific temperature, and it is typically expressed as g/100 mL or mL/L.
The correct answer is option D, which is to increase the temperature and raise the pressure to increase solubility of a gas into a liquid the most. Solubility is the maximum quantity of a substance that can be dissolved in a particular solvent at a specific temperature, and it is typically expressed as g/100 mL or mL/L. The concentration of a dissolved gas in a liquid is governed by Henry's law. According to Henry's law, the amount of a gas that dissolves in a liquid is directly proportional to the pressure of the gas above the liquid (or in contact with the liquid). When pressure is increased, the solubility of a gas in a liquid rises. Furthermore, when the temperature of the solution is raised, the solubility of gases in liquids decreases because the rate of escaping gas molecules is raised when temperature is raised. Therefore, to increase the solubility of a gas in a liquid the most, you must increase the pressure and temperature.
The solution needs to be at a high pressure so that more gas molecules are available to dissolve in the liquid. A high-temperature solvent also has more kinetic energy, which allows it to dissolve more gas. Furthermore, reducing the pressure has the opposite effect, causing the gas to bubble out of the liquid. A decrease in temperature reduces the solubility of a gas in a liquid.
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chromatography of food dyes lab why is it important to mark the solvent level on the chromatography paper as soon as you remove it from the petri dish
It is important to mark the solvent level on the chromatography paper as soon as you remove it from the petri dish in a chromatography of food dyes lab because if the solvent level is not marked as soon as possible, the solvent front can evaporate causing the results to be inaccurate.
Chromatography is a laboratory technique for separating a mixture into its individual components. The mixture is dissolved in a solvent and then placed in contact with a stationary phase. The components of the mixture are then separated based on their individual interactions with the stationary phase and the solvent. Chromatography of food dyes is a lab that is used to separate different food dyes that are present in a sample.
The sample is placed on chromatography paper which is then placed in a petri dish containing a solvent. As the solvent moves up the chromatography paper, the different dyes in the sample are separated based on their individual interactions with the paper and the solvent.
In a chromatography of food dyes lab, it is important to mark the solvent level on the chromatography paper as soon as it is removed from the petri dish because the solvent front can evaporate causing the results to be inaccurate. If the solvent front evaporates, the distance traveled by the different dyes will be shorter, making it appear as though they are less separated than they actually are.
By marking the solvent level as soon as possible, the distance traveled by the different dyes can be accurately measured, and the results will be more accurate.
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The reason why it is important to mark the solvent level on the chromatography paper as soon as you remove it from the petri dish is that the solvent level must be measured to calculate the Rf value. The Rf value is a way to quantify how far a particular compound travels in chromatography.
It is calculated as the distance traveled by the compound divided by the distance traveled by the solvent.The chromatography of food dyes lab is a experiment that aims to identify the dyes used in food products by using paper chromatography. The procedure includes: Cut a strip of chromatography paper and mark the solvent level using a pencil as soon as you remove it from the petri dish; prepare the chromatography solvent by mixing rubbing alcohol with water; then, spot the dyes on the chromatography paper using toothpicks or capillary tubes.
Afterwards, place the paper in the petri dish containing the solvent, making sure that the dyes do not touch the solvent, and cover it. Allow the solvent to travel up the paper until it reaches the solvent level mark. Once the solvent level has reached the mark, remove the paper from the petri dish and allow it to dry before analyzing the results.
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what is the ph of a 0.125 m solution of barium butyrate at 25 °c?
The pH of a 0.125 M solution of barium butyrate at 25 °C is not readily determined without additional information.
To determine the pH of a solution, we need to know the nature of the compound and its dissociation behavior in water. Barium butyrate is a salt composed of the metal barium and the butyrate anion. Without specific information about the dissociation of barium butyrate in water and the presence of any acid-base reactions, we cannot directly calculate the pH of the solution.
However, we can make some general observations. Barium butyrate is a salt formed by the reaction of barium hydroxide (a strong base) and butyric acid (a weak acid). The barium ion (Ba²⁺) is the conjugate acid of a strong base, and the butyrate ion (C₄H₇O₂⁻) is the conjugate base of a weak acid.
Therefore, the solution of barium butyrate may have a slightly basic pH due to the presence of the barium hydroxide. However, the extent of this basicity will depend on the concentration of the barium hydroxide and the degree of dissociation of butyric acid.
In conclusion, without specific information about the dissociation behavior of barium butyrate and the presence of other acids or bases in the solution, the pH of a 0.125 M solution of barium butyrate at 25 °C cannot be determined accurately.
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The pH of a 0.125 M solution of barium butyrate at [tex]25^0C[/tex] depends on the dissociation of the compound in water, which can be determined using the ionization constant (Ka) and the concentration of the solution.
The pH of a solution is a measure of its acidity or basicity and is determined by the concentration of hydrogen ions ([tex]H^+[/tex]) present in the solution. To calculate the pH of a 0.125 M solution of barium butyrate, we need to consider the dissociation of the compound in water. Barium butyrate is a salt that dissociates into its constituent ions in solution, including the barium ion ([tex]Ba^2^+[/tex]) and the butyrate ion ([tex]C_4H_7O_2^-[/tex]).
To calculate the pH, we need to know the ionization constant (Ka) of butyric acid, the parent acid of butyrate. Assuming that the butyrate ion acts as a weak base, we can use the Ka value to determine the concentration of hydroxide ions ([tex]OH^-[/tex]) in the solution. From there, we can calculate the concentration of [tex]H^+[/tex] ions and convert it into pH.
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acetylene is unstable at temperatures above ____ fahrenheit.
Acetylene is unstable at temperatures above 300 degrees fahrenheit.
At temperatures, more than 149 degrees Celsius (300 degrees Fahrenheit), acetylene (C2H2) is typically regarded as unstable.
Acetylene can undergo a self-decomposition reaction at temperatures over this limit, resulting in a highly exothermic and perhaps explosive decomposition.
Acetylene is often carried and stored in specialised containers made to reduce the risk of temperature and pressure accumulation in order to ensure safe handling and storage.
Acetylene can become highly reactive and prone to breakdown at temperatures higher than this, resulting in dangerous situations and the possibility of explosions.
To reduce the hazards, handling and storing acetylene safely is essential while adhering to all applicable laws and regulations.
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Amino acids can be synthesized by reductive amination. Draw the structure of the organic compound that you would use to synthesize glutamic acid. •. You do not have to consider stereochemistry. • Draw the molecule with ionizable groups in their uncharged form. • In cases where there is more than one answer, just draw one.
The organic compound used to synthesize glutamic acid through reductive amination is α-ketoglutarate.
What is the precursor compound for synthesizing glutamic acid through reductive amination?
Reductive amination is a chemical reaction that involves the conversion of a carbonyl compound, such as an aldehyde or a ketone, into an amine. In the case of synthesizing glutamic acid, the precursor compound used is α-ketoglutarate.
α-ketoglutarate is an organic compound that belongs to the family of alpha-keto acids. It has a carboxyl group and a keto group, making it suitable for reductive amination reactions. By reacting α-ketoglutarate with an amine, such as ammonia or an amine derivative, and employing a reducing agent, such as sodium borohydride, glutamic acid can be synthesized.
Glutamic acid is one of the 20 amino acids that serve as the building blocks of proteins. It plays important roles in various biological processes, including protein synthesis and neurotransmitter function. The synthesis of glutamic acid through reductive amination using α-ketoglutarate allows for the production of this essential amino acid.
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If balloon is filled with 20L of helium gas at STP. How many grams of helium does it contain?
If balloon is filled with 20L of helium gas at STP then it contain 3.20 grams of helium.
The ideal gas law, PV=nRT, relates the pressure, volume, temperature, and number of moles of a gas.
The equation can be rearranged as follows: n = PV/RT where n is the number of moles of gas, P is the pressure, V is the volume, R is the ideal gas constant (0.0821 L atm/mol K), and T is the temperature in Kelvin (273 K at STP).
Since the balloon is filled with helium at STP, the temperature and pressure are standard.
Therefore, the equation can be simplified to:n = (1 atm) (20 L) / (0.0821 L atm/mol K) (273 K) = 0.8 mol of helium.
In order to convert from moles to grams, the molar mass of helium must be known.
The molar mass of helium is 4.00 g/mol, so the mass of helium can be calculated as follows:m = n x M where m is the mass of the helium and M is the molar mass of helium.m = (0.8 mol) (4.00 g/mol) = 3.20 g
Therefore, the 20-liter helium-filled balloon at STP contains 3.20 grams of helium.
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in the experimental procedure, which step would be made easier through the application of ultrasonic waves?
The dispersion and mixing of particles would be made easier through the application of ultrasonic waves.
Which step in the experimental procedure benefits from the application of ultrasonic waves?Ultrasonic waves can facilitate the dispersion and mixing of particles in an experimental procedure. When ultrasonic waves are applied, they generate high-frequency sound waves that create alternating compression and rarefaction waves in a liquid medium.
These waves produce tiny bubbles due to the phenomenon of cavitation. During cavitation, the bubbles rapidly expand and collapse, creating localized areas of high pressure and temperature.
This process exerts mechanical forces on the surrounding particles, leading to their effective dispersion and mixing. The energy from ultrasonic waves helps to break down agglomerates, disperse fine particles, and enhance the overall homogeneity of the mixture.
The application of ultrasonic waves can be particularly beneficial in procedures such as sample preparation, emulsification, dispersion of nanoparticles, and dissolution of substances. It improves the efficiency and effectiveness of processes that require uniform distribution and thorough mixing of components.
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how is a trihalomethane molecule different from a methane molecule
A trihalomethane molecule is different from a methane molecule in terms of the presence of halogen atoms.
The carbon atom in a methane molecule (CH4) is joined to four hydrogen atoms to form the compound. It is a straightforward hydrocarbon and doesn't have any halogen atoms in it.
A trihalomethane molecule, on the other hand, is a halogenated form of methane.
It is similar to methane in that it has one carbon atom connected to three hydrogen atoms, but it additionally has three halogen atoms (fluorine, chlorine, bromine, or iodine) coupled to the carbon atom.
Iodoform (CHI3), bromoform (CHBr3), and chloroform (CHCl3) are a few examples of trihalomethanes.
Trihalomethanes differ from methane molecules in the chemical characteristics and reactivities introduced by the addition of halogen atoms. Polarity, boiling point, and solubility are impacted by it.
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what is the average rate of change for the sequence shown below? (1 point) coordinate plane showing the points 1, 2; 2, 2.5; 3, 3; 4, 3.5; and 5, 4 −2 −one half one half 2
Answer: The average rate of change for the sequence shown below is 0.5.
Given below is the coordinate plane with points: (1, 2), (2, 2.5), (3, 3), (4, 3.5) and (5, 4).The average rate of change for the sequence shown in the coordinate plane can be calculated by finding the slope of the line that passes through all the given points.
Therefore, we will find the slope of the line using any two points and check if the slope is same for the remaining points.
To find the slope of the line, we will use the slope-intercept form of equation y = mx + c. Where m is the slope of the line and c is the y-intercept of the line.(1, 2) and (2, 2.5) m = (y₂ - y₁) / (x₂ - x₁) = (2.5 - 2) / (2 - 1) = 0.5(2, 2.5) and (3, 3) m = (y₂ - y₁) / (x₂ - x₁) = (3 - 2.5) / (3 - 2) = 0.5(3, 3) and (4, 3.5) m = (y₂ - y₁) / (x₂ - x₁) = (3.5 - 3) / (4 - 3) = 0.5(4, 3.5) and (5, 4) m = (y₂ - y₁) / (x₂ - x₁) = (4 - 3.5) / (5 - 4) = 0.5.
We can see that the slope of the line passing through all the given points is constant and is equal to 0.5. Hence, the average rate of change for the sequence shown in the coordinate plane is 0.5.
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concentration gradient Serotonin and dopamine transporters on the plasma membrane use the to transport these neurotransmitters across the membrane O Calcium O Glucose O Proton O Sodium Question 6 Which of the following concentration gradients is used by vesicular transporters to transport serotonin and dopamine into synaptic vesicles? O Sodium O Potassium O ATP o Proton
Concentration gradient Serotonin and dopamine transporters on the plasma membrane use the to transport these neurotransmitters across the membrane D. sodium. The following concentration gradients is used by vesicular transporters to transport serotonin and dopamine into synaptic vesicles is C. Proton
Serotonin and dopamine are vital neurotransmitters that are responsible for a wide range of physiological functions in the brain, these neurotransmitters are transported across the plasma membrane of neurons through active transporters. The concentration gradient is the difference in solute concentration across a membrane, it is the driving force behind many processes in the body, including the transport of neurotransmitters like serotonin and dopamine. Transporters on the plasma membrane use the sodium concentration gradient to transport these neurotransmitters across the membrane. Sodium concentration gradient acts as an energy source for these transporters.
Vesicular transporters, on the other hand, use a proton concentration gradient to transport serotonin and dopamine into synaptic vesicles. This process is known as the proton-pumping mechanism, where the transporter pumps protons into the vesicle, causing a change in the pH gradient that leads to the uptake of neurotransmitters. So the correct answer for first question is D. sodium concentration gradient used to transport these neurotransmitters across the membrane and the second question correct answer is C. Proton concentration gradient is used by vesicular transporters to transport serotonin and dopamine into synaptic vesicles.
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Serotonin and dopamine transporters on the plasma membrane use the concentration gradient to transport these neurotransmitters across the membrane. This gradient is established by the unequal distribution of the neurotransmitters between the extracellular fluid and the cytosol of the neurons. Vesicular transporters use a proton concentration gradient to transport serotonin and dopamine into synaptic vesicles.
The transporters move these neurotransmitters against the concentration gradient, requiring energy to do so. The transporters use the energy provided by the concentration gradient to transport the neurotransmitters across the membrane.The neurotransmitter serotonin (5-HT) is released into the synaptic cleft via exocytosis by the presynaptic neuron. Serotonin transporters (SERTs) are responsible for the reuptake of serotonin from the synaptic cleft and are located on the plasma membrane of presynaptic neurons. These transporters use the concentration gradient of sodium ions to transport serotonin across the membrane and into the presynaptic neuron.Dopamine transporters (DATs) are responsible for the reuptake of dopamine from the synaptic cleft and are also located on the plasma membrane of presynaptic neurons. These transporters use the concentration gradient of sodium ions to transport dopamine across the membrane and into the presynaptic neuron.Vesicular transporters use a proton concentration gradient to transport serotonin and dopamine into synaptic vesicles.
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The synthesis of methanol from carbon monoxide and hydrogen gas is described by the following chemical equation:
CO(g)+2H2(g)⇌CH3OH(g)
The equilibrium constant for this reaction at 25 ∘Cis Kc=2.3×104. In this trial, you will use the equilibrium-constant expression to find the concentration of methanol at equilibrium, given the concentration of the reactants.
Suppose that the molar concentrations for CO and H2 at equilibrium are [CO] = 0.04 M and [H2] = 0.04 M.
Use the formula you found in Part B to calculate the concentration of CH3OH.
The equilibrium concentration of CH3OH can be determined by the following formula: [CH3OH] = [CO] × Kc= 0.04 × 2.3 × 104= 0.92 M Therefore, the concentration of CH3OH at equilibrium is 0.92 M.
The given chemical equation can be used to represent the synthesis of methanol from carbon monoxide and hydrogen gas.CO(g) + 2H2(g) ⇌ CH3OH(g)The equilibrium constant for this reaction at 25 ∘C is Kc = 2.3 × 104
In this case, we are required to use the equilibrium-constant expression to determine the concentration of methanol at equilibrium, considering the concentration of the reactants.
Suppose that the molar concentrations for CO and H2 at equilibrium are [CO] = 0.04 M and [H2] = 0.04 M. Using the law of mass action, we can write the equilibrium-constant expression for the given reaction as:
Kc = [CH3OH]/[CO][H2]Substituting the given values,
we have:2.3 × 104 = [CH3OH]/(0.04)2 Since the stoichiometric ratio of CO to CH3OH is 1:1,
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what volume (in ml) of 0.250 m hcl would be required to completely react with 4.10 g of al in the following chemical reaction? 2 al(s) 6 hcl(aq) → 2 alcl₃ (aq) 3 h₂(g)
1823 mL of 0.250 M HCl are required to completely react with 4.10 g of Al. The balanced chemical equation is: 2Al (s) + 6HCl (aq) → 2AlCl3 (aq) + 3H2 (g)The molar mass of Al is 27 g/mol.
The given mass of Al is 4.10 g.Convert the mass of Al to moles:4.10 g Al × (1 mol Al/27 g Al) = 0.1519 mol AlAccording to the balanced chemical equation, the reaction of 2 moles of Al with 6 moles of HCl will produce 2 moles of AlCl3. This can be used to calculate the moles of HCl required to react with the given mass of Al
The volume (in mL) of 0.250 M HCl required to react with 0.4557 mol HCl can be calculated using the formula:Mo l a r i t y ( M ) = n u m b e r o f m o l e s o f s o l u t e v o l u m e o f s o l u t i o n i n l i t e r s0.250 M = 0.4557 mol HCl/VHClVHCl = 0.4557 mol HCl/0.250 M = 1.823 LConvert 1.823 L to mL:1 L = 1000 mL1.823 L = 1823 mL.
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1a. If 0.619 g of magnesium hydroxide reacts with 0.940 g of sulfuric acid, what is the mass of magnesium sulfate produced? Mg(OH)2(s)+H2SO4(l)→MgSO4(s)+H2O(l)
The mass of magnesium sulfate produced is 0.929 g. To find the mass of magnesium sulfate produced, we first need to determine the limiting reactant. We can do this by calculating the moles of each reactant using their molar masses.
The molar mass of magnesium hydroxide (Mg(OH)2) is 58.33 g/mol, and the molar mass of sulfuric acid (H2SO4) is 98.09 g/mol.
The moles of magnesium hydroxide can be calculated as follows:
[tex]\[\text{{moles of Mg(OH)}}_2 = \frac{{\text{{mass of Mg(OH)}}_2}}{{\text{{molar mass of Mg(OH)}}_2}} = \frac{{0.619 \, \text{g}}}{{58.33 \, \text{g/mol}}} = 0.0106 \, \text{mol}\][/tex]
Similarly, the moles of sulfuric acid can be calculated as follows:
[tex]\[\text{{moles of H}}_2\text{{SO}}_4 = \frac{{\text{{mass of H}}_2\text{{SO}}_4}}{{\text{{molar mass of H}}_2\text{{SO}}_4}} = \frac{{0.940 \, \text{g}}}{{98.09 \, \text{g/mol}}} = 0.0096 \, \text{mol}\][/tex]
From the balanced chemical equation, we can see that the stoichiometric ratio between magnesium hydroxide and magnesium sulfate is 1:1. This means that for every 1 mole of magnesium hydroxide, we will produce 1 mole of magnesium sulfate.
Since the moles of sulfuric acid (0.0096 mol) are less than the moles of magnesium hydroxide (0.0106 mol), sulfuric acid is the limiting reactant. Therefore, all of the sulfuric acid will be consumed in the reaction.
The molar mass of magnesium sulfate (MgSO4) is 120.37 g/mol. Using the stoichiometry, we can calculate the mass of magnesium sulfate produced:
[tex]\[\text{{mass of MgSO}}_4 = \text{{moles of MgSO}}_4 \times \text{{molar mass of MgSO}}_4 = 0.0096 \, \text{mol} \times 120.37 \, \text{g/mol} = 0.929 \, \text{g}\][/tex]
Therefore, the mass of magnesium sulfate produced is 0.929 g.
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What temperature change in C is produced when 800 calories are absorbed by 100 g of water?
the temperature change produced when 800 calories are absorbed by 100 g of water is 8°C.
When 800 calories of heat are absorbed by 100 g of water, the temperature change that occurs can be calculated using the specific heat capacity of water.
The specific heat capacity of water is the amount of heat energy required to raise the temperature of 1 gram of water by 1 degree Celsius. It is 1 calorie/gram°C.
Therefore, to calculate the temperature change in Celsius produced when 800 calories of heat are absorbed by 100 g of water, we can use the following formula:Q = m × c × ΔTwhere Q = heat energy absorbed, m = mass of water, c = specific heat capacity of water, and ΔT = change in temperature.
Substituting the values, we get:800 = 100 × 1 × ΔTΔT = 800/100ΔT = 8°CTherefore, the temperature change produced when 800 calories are absorbed by 100 g of water is 8°C.
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the imidazole side chain of histidine can function as either a general acid catalyst or a general base catalyst because _____.
If the pH of the environment is greater than the pKa of the imidazole side chain, the imidazole will be deprotonated and will function as a general base catalyst by accepting a proton.
The imidazole side chain of histidine can function as either a general acid catalyst or a general base catalyst because it can donate or accept a proton, depending on the pH of the environment. In its neutral form, the imidazole side chain has a pKa of approximately 6, which means that it can act as either an acid or a base at physiological pH.A general acid catalyst is a molecule that donates a proton to a substrate, while a general base catalyst is a molecule that accepts a proton from a substrate. The imidazole side chain of histidine can perform both functions because it has a pKa that is close to physiological pH. If the pH of the environment is less than the pKa of the imidazole side chain, the imidazole will be protonated and will function as a general acid catalyst by donating a proton. If the pH of the environment is greater than the pKa of the imidazole side chain, the imidazole will be deprotonated and will function as a general base catalyst by accepting a proton.
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The standard free energy of formation of ammonia is −16.5 kJ/mol. N 2
(g)+3H 2
(g)⇌2NH 3
(g) 5th attempt What is the value of K for the reaction below at 555.0 K ?
the value of K for the reaction N₂(g) + 3H₂(g) ⇌ 2NH₃(g) at 555.0 K if the standard free energy of formation of ammonia is −16.5 kJ/mol is 4.75 × 10⁶.
The relationship between the standard free energy of the formation of a chemical compound and the equilibrium constant (K) of the reaction is given by the formula:
ΔG° = −RT ln(K)
Where:
R is the gas constantT is the temperature in KelvinΔG° is the standard free energy change of the reaction.To calculate the value of K, the standard free energy change is given as ΔG° = −16.5 kJ/mol and at a temperature of 555 K:
K = e^(-ΔG° / RT)
K = e^(-(-16.5 × 10₃ J/mol) / (8.314 J/mol·K × 555 K))
K = 4.75 × 10⁶
Therefore, the value of K for the given reaction at 555 K is 4.75 × 10⁶.
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Given that the standard free energy of formation of ammonia is −16.5 kJ/mol.
The balanced chemical equation for the reaction:
N2(g)+3H2(g) ⇌ 2NH3(g)
the value of K for the reaction = 3.17×10⁻¹²
Given that the standard free energy of formation of ammonia is −16.5 kJ/mol.
The balanced chemical equation for the reaction:
N2(g)+3H2(g) ⇌ 2NH3(g)
The standard free energy of reaction, ΔGºr is given by
ΔGºr=ΔGºf(products)−ΔGºf(reactants)
ΔGºr=2×ΔGºf(NH3)−ΔGºf(N2)−3×ΔGºf(H2)
Use the values of the standard free energy of formation of the elements and ammonia as given below,
ΔGºf(H2)=0 kJ/mol
ΔGºf(N2)=0 kJ/mol
ΔGºf(NH3)=−16.5 kJ/mol
Putting these values in the above equation we get,
ΔGºr=2×(−16.5 kJ/mol)−(0 kJ/mol)−3×(0 kJ/mol)ΔGºr=−33 kJ/mol
Now, we use the relation between ΔGºr and K given by,
ΔGºr=−RTlnK
At 555.0 K, we have R = 8.314 J/mol K
The value of T should be converted to Kelvin before substituting in the above equation.
So, the value of T = 555 K + 273 K = 828 K
Now, substituting the values of ΔGºr, R and T, we get,
−33 kJ/mol=−8.314 J/molK× 828KlnK
lnK=−33000J/mol−1×1kJ/1000J
lnK=−27.58K=3.17×10⁻¹²Answer: K = 3.17×10⁻¹²
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Which of the following aqueous solutions contains the lowest amount of ions or molecules dissolved in water? 500 ml of 2.25 M CH3OH 500 ml of 0.75 M Nal 1.5L of 0.5 M Na3PO4 20L of 225 M CUCI 1.75L of 1.25 M HBO,
To determine the solution with the lowest amount of ions or molecules dissolved in water, we need to calculate the total number of ions or molecules in each solution.
1. 500 ml of 2.25 M [tex]CH_3OH[/tex]:
Methanol [tex]CH_3OH[/tex] does not ionize or dissociate in water. Therefore, the total number of ions or molecules in this solution is equal to the number of moles of [tex]CH_3OH[/tex]. Since the molarity is given as 2.25 M, the number of moles can be calculated as follows:
Moles of [tex]CH_3OH[/tex]= molarity × volume
Moles of [tex]CH_3OH[/tex]= 2.25 M × 0.5 L (converting 500 ml to liters)
Moles of [tex]CH_3OH[/tex] = 1.125 mol
Thus, this solution contains 1.125 moles of [tex]CH_3OH[/tex]:.
2. 500 ml of 0.75 M NaI:
Sodium iodide (NaI) dissociates into Na+ and I- ions in water. The total number of ions in this solution can be calculated as follows:
Moles of NaI = molarity × volume
Moles of NaI = 0.75 M × 0.5 L
Moles of NaI = 0.375 mol
Since NaI dissociates into one Na+ ion and one I- ion, the total number of ions in this solution is twice the number of moles of NaI:
Total ions = 2 × Moles of NaI
Total ions = 2 × 0.375 mol
Total ions = 0.75 moles of ions
Thus, this solution contains 0.75 moles of ions.
3. 1.5 L of 0.5 M [tex]Na_3PO_4[/tex]:
Sodium phosphate [tex]Na_3PO_4[/tex] dissociates into three Na+ ions and one [tex]PO_4^{3-}[/tex] ion in water. The total number of ions in this solution can be calculated as follows:
Moles of [tex]Na_3PO_4[/tex] = molarity × volume
Moles of [tex]Na_3PO_4[/tex] = 0.5 M × 1.5 L
Moles of [tex]Na_3PO_4[/tex] = 0.75 mol
Since [tex]Na_3PO_4[/tex] dissociates into three Na+ ions and one [tex](PO)_4^{3-}[/tex] ion, the total number of ions in this solution can be calculated as follows:
Total ions = 3 × Moles of [tex]Na_3PO_4[/tex] + 1 × Moles of [tex]Na_3PO_4[/tex]
Total ions = 3 × 0.75 mol + 1 × 0.75 mol
Total ions = 3.75 moles of ions
Thus, this solution contains 3.75 moles of ions.
4. 20 L of 225 M CuCl:
Copper chloride (CuCl) dissociates into one Cu2+ ion and two Cl- ions in water. The total number of ions in this solution can be calculated as follows:
Moles of CuCl = molarity × volume
Moles of CuCl = 225 M × 20 L
Moles of CuCl = 4500 mol
Since CuCl dissociates into one Cu2+ ion and two Cl- ions, the total number of ions in this solution can be calculated as follows:
Total ions = 1 × Moles of CuCl + 2 × Moles of CuCl
Total ions = 1 × 4500 mol + 2 × 4500 mol
Total ions = 13500 moles of ions
Thus, this solution
contains 13,500 moles of ions.
5. 1.75 L of 1.25 M HBO:
Boric acid (HBO) does not fully dissociate in water. Therefore, we need to consider the undissociated molecules in this solution. The total number of molecules in this solution can be calculated as follows:
Moles of HBO = molarity × volume
Moles of HBO = 1.25 M × 1.75 L
Moles of HBO = 2.1875 mol
Thus, this solution contains 2.1875 moles of HBO molecules.
Comparing the total number of ions or molecules in each solution, we can conclude that the solution with the lowest amount of ions or molecules dissolved in water is 500 ml of 2.25 M CH3OH, which contains only 1.125 moles of CH3OH molecules.
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determine the redox reaction represented by the following cell notation. ba(s) ∣ ba2 (aq) ‖ cu2 (aq) ∣ cu(s)
The given cell notation represents a redox reaction where barium (Ba) is oxidized at the anode, releasing electrons, while copper (Cu) is reduced at the cathode, gaining electrons.
The cell notation ba(s) ∣ ba2 (aq) ‖ cu2 (aq) ∣ cu(s) represents a galvanic cell with two half-cells separated by a salt bridge. In the anode compartment (left side), solid barium (Ba) is oxidized to barium ions (Ba2+). This can be represented by the half-reaction:
Ba(s) → Ba2+(aq) + 2e^-
At the cathode compartment (right side), copper ions (Cu2+) are reduced to solid copper (Cu) by gaining electrons. This can be represented by the half-reaction:
Cu2+(aq) + 2e^- → Cu(s)
Overall, the redox reaction can be obtained by combining the two half-reactions:
Ba(s) + [tex]Cu_2+(aq)[/tex] → [tex]Ba_2+(aq)[/tex] + Cu(s)
In this reaction, barium is oxidized (loses electrons) and copper is reduced (gains electrons), making it a redox reaction. The electrons released by barium at the anode flow through the external circuit to the cathode, where they are consumed in the reduction of copper ions. This flow of electrons generates an electric current in the cell.
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when reactions occur in aqueous solutions, what common types of products are produced?
The common types of products produced when reactions occur in aqueous solutions are acids, bases, and salts.
When chemical reactions occur in aqueous solutions, the products that form may be acids, bases, or salts depending on the nature of the reactants involved. For example, when a strong acid reacts with a strong base, the products formed are water and a salt. If a metal reacts with an acid, the products are salt and hydrogen gas. In some cases, there may be no visible evidence of a chemical reaction as the products remain in solution.
Furthermore, some reactions may involve the exchange of ions, such as precipitation reactions, which occur when an insoluble salt forms due to the mixing of two solutions. In summary, the common types of products that are produced when reactions occur in aqueous solutions are acids, bases, and salts.
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Aluminum is reacted with calcium chloride and produces calcium and aluminum chloride. If 4.7 grams of calcium chloride are completely used up in the
reaction, how many grams of calcium will be produced?
Approximately 1.693 grams of calcium will be produced when 4.7 grams of calcium chloride are completely used up in the reaction.
To determine the grams of calcium produced, we need to calculate the molar ratio between calcium chloride (CaCl2) and calcium (Ca) in the balanced chemical equation for the reaction. The balanced equation is:
2Al + 3CaCl2 → 3Ca + 2AlCl3
From the balanced equation, we can see that for every 3 moles of calcium chloride, 3 moles of calcium are produced. We need to convert the given mass of calcium chloride (4.7 grams) to moles using its molar mass.The molar mass of CaCl2 is calculated by adding the atomic masses of calcium (Ca) and chlorine (Cl). The atomic mass of calcium is 40.08 g/mol, and the atomic mass of chlorine is 35.45 g/mol.
Molar mass of CaCl2 = (40.08 g/mol) + 2(35.45 g/mol) = 110.98 g/mol
Now we can calculate the moles of calcium chloride:
Moles of CaCl2 = (mass of CaCl2) / (molar mass of CaCl2)
= 4.7 g / 110.98 g/mol
≈ 0.0423 mol
Since the molar ratio between calcium chloride and calcium is 3:3, the moles of calcium produced will be equal to the moles of calcium chloride used.
Moles of Ca = 0.0423 mol
To convert moles of calcium to grams, we multiply by the molar mass of calcium:
Mass of Ca = (moles of Ca) × (molar mass of Ca)
= 0.0423 mol × 40.08 g/mol
≈ 1.693 g
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Based on the Kb values, which of the following corresponds to the strongest base?
Select the correct answer below:
A• 4.1 × 10^-4
• B. 0.07
• C. 6.7 × 10^-3
D. 4.9 × 10^-9
The strongest base among the given options is option (B) with a Kb value of 0.07, indicating a higher concentration of hydroxide ions. Option B is the strongest base based on Kb values.
To determine the strongest base based on the given Kb values, we need to compare the values of Kb. The Kb value represents the equilibrium constant for the reaction of a base with water to form hydroxide ions (OH⁻).
Comparing the given Kb values:
A. 4.1 × 10⁻⁴
B. 0.07
C. 6.7 × 10⁻³
D. 4.9 × 10⁻⁹
A higher Kb value indicates a stronger base because it corresponds to a larger concentration of hydroxide ions at equilibrium. Therefore, the base with the highest Kb value is the strongest.
From the given options, the base with the highest Kb value is option B, with a Kb value of 0.07. This indicates that option B is the strongest base among the given choices.
In summary, option B, with a Kb value of 0.07, corresponds to the strongest base among the provided options.
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For each of the following strong base solutions, determine [OH−][OH−] and [H3O+][H3O+] and pHpH and pOHpOH.
For 5.2×10−45.2×10−4 MM Ca(OH)2Ca(OH)2, determine [OH−][OH−] and [H3O+][H3O+].
Calculating reaction [OH-][OH-]:[Ca(OH)2] = 5.2 × 10−4 M No. Therefore, [OH-][OH-] = 1.04 × 10−3 M.
OH- ions from one molecule of Ca(OH)2 = 2Moles of OH- ions from [Ca(OH)2] = 2 × [Ca(OH)2] = 2 × 5.2 × 10−4M = 1.04 × 10−3 M Therefore, [OH-][OH-] = 1.04 × 10−3 M. Calculating [H3O+][H3O+]:As we know that water is neutral and the product of [H3O+] and [OH-] is equal to 10^-14[H3O+][OH−] = 1.0 × 10−14 pOH = −log[OH−][OH−] = antilog (−pOH)pH = 14.00 − pOHpOH = −log[OH−][OH−].
Substituting values, we get:[OH-][OH-] = 1.04 × 10−3 M[H3O+] = 1.0 × 10−14/[OH-] = 1.0 × 10^-14/1.04 × 10−3 = 9.615 × 10^-12 M(pH) = 14.00 - pOH = 14.00 - 11.02 = 2.98(pOH) = -log[OH−][OH−] = -log(1.04 × 10^-3) = 2.98Therefore, the values of [OH-], [H3O+], pH, and pOH are 1.04 × 10^-3 M, 9.615 × 10^-12 M, 2.98 and 11.02 respectively.
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Select the structure of the intermediate carbocation in the reaction. E is an abbreviation for electrophile. C6H6 +E+ + Intermediate + CH_X + H+ The structure of the intermediate is: H H E H B Ε EH
The structure of the intermediate carbocation in the given reaction is E. The intermediate structure is represented as follows: C6H6 + E+ → Intermediate + CH_X + H+Here, E represents the electrophile.
The structure of the intermediate is E, which is an electrophile. In the reaction, C6H6 + E+ + Intermediate + CH_X + H+, benzene reacts with an electrophile, E+. This leads to the formation of an intermediate carbocation and CH_X as a byproduct. Finally, H+ acts as a proton donor to produce the desired product.
The reaction can be summarized as: C6H6 + E+ → Intermediate + CH_X + H+The structure of the intermediate is E, which represents the electrophile. Therefore, the correct answer is E.
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1. How many ATOMS of hydrogen are present in 2.53 grams of water ? atoms of hydrogen .
2. How many GRAMS of oxygen are present in 4.74×1022 molecules of water ? grams of oxygen
3. How many MOLECULES of nitrogen dioxide are present in 4.25 grams of this compound ? molecules.
4. How many GRAMS of nitrogen dioxide are present in 3.05×1021 molecules of this compound ? Grams?
5. For the molecular compound xenon trioxide , what would you multiply "grams of XeO3 " by to get the units "molecules of XeO3 " ?
To determine the amount of grams of oxygen in 4.74 × 10²² molecules of water, we will use the formula; n=m/M, where n= number of moles, m=mass of the substance, M= molar mass of the substance. From the balanced equation of water (H2O), we know that 1 mole of water contains 2 moles of hydrogen atoms and 1 mole of oxygen atoms.
1. In 2.53 grams of water, there are 2.85 × 10²³ atoms of hydrogen.
2. To determine the amount of grams of oxygen in 4.74 × 10²² molecules of water, we will use the formula; n=m/M, where n= number of moles, m=mass of the substance, M= molar mass of the substance. From the balanced equation of water (H2O), we know that 1 mole of water contains 2 moles of hydrogen atoms and 1 mole of oxygen atoms. So, 1 mole of water = (2 × 1.01g) + (1 × 16g) = 18.02g
1 mole of water = 6.02 × 10²³ molecules of water.
Molar mass of water (H2O) = 18.02g/mol
Number of moles of water present in 4.74 × 10²² molecules of water; n=m/M; 4.74 × 10²² molecules × 1mol/6.02 × 10²³ molecules per mole = 0.788mol
Since the mole ratio of oxygen to water is 1:1, there are 0.788 moles of oxygen in 4.74 × 10²² molecules of water. Mass of oxygen = number of moles × molar mass= 0.788 mol × 16 g/mol= 12.6 g
Therefore, there are 12.6 grams of oxygen in 4.74 × 10²² molecules of water.
3. To calculate the number of molecules in 4.25 grams of nitrogen dioxide, we will use the formula, n = m/M, where n= number of moles, m= mass of the substance, M= molar mass of the substance. The formula of nitrogen dioxide (NO2) shows that it has 2 atoms of nitrogen and 2 atoms of oxygen. The molar mass of NO2 is 46 g/mol.
Mass of nitrogen dioxide = 4.25 g
Number of moles of NO2 present = 4.25 g/46 g/mol= 0.09239 mol
The number of molecules = number of moles × Avogadro's number= 0.09239 mol × 6.02 × 10²³ = 5.56 × 10²² molecules.
4. The mass of nitrogen dioxide present in 3.05 × 10²¹ molecules of this compound can be calculated as follows: The formula of nitrogen dioxide (NO2) shows that it has 2 atoms of nitrogen and 2 atoms of oxygen. The molar mass of NO2 is 46 g/mol. The number of moles of NO2 = number of molecules / Avogadro's number= 3.05 × 10²¹/6.02 × 10²³= 0.00507mol
The mass of nitrogen dioxide present = number of moles × molar mass= 0.00507 × 46= 0.23 g
5. The number of molecules of XeO3 can be calculated by multiplying the grams of XeO3 by Avogadro's number divided by molar mass. Therefore, to calculate the number of molecules of XeO3, we will use the formula;n = m/M × NA
Where; n=number of molecules, m= mass of the compound
M= molar mass of the compound
NA = Avogadro's number
Molar mass of XeO3 = 195.29g/mol
So, to get the units of "molecules of XeO3," you will multiply the grams of XeO3 by Avogadro's number divided by the molar mass of XeO3; n= m/M × NA= (grams of XeO3 / Molar mass of XeO3) × Avogadro's number= (grams of XeO3 / 195.29) × 6.02 × 10²³.
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