Answer:
how many mols of nh4cl are present in 279.0ml of a 0.975 M nh4cl soution?
Assume you have 4 solids (A, B, C and D) of similar mass. Which of these requires the greatest energy input to melt?
polar covalent
covalent network
ionic compound
nonpolar covalent
The solid that require the greatest energy input to melt by mass is the option;
Covalent network
Reason for the above answer is as follows;
The elementary particles of a solid are held together by bonds that require
an input of energy to unlock, and once broken, the particles are then able
to change location within their containing vessels with less restrictions
Types of bonds
Polar covalent molecular solids have the following characteristics;a) Soluble in water b) Low melting point, b) Conduct electricity
Solids that are made up of a covalent network have the following characteristicsa) High melting point temperature b) Non conductive of electricity c) Not soluble in water
Solids of ionic compounds have the following characteristics;a) High melting point temperature b) The liquid state and solution
conducts electricity c) Soluble in water
Solids that have nonpolar covalent bonds have;a) Low melting point b) Normally in the gaseous or liquid state b) Not water soluble
Therefore, the covalent network, and the solids ionic compounds require the most energy to melt, however, the strength of the ionic bond in an ionic compound is a factor the charges present and the sizes of the atom, while
the covalent network solid, are combined to form essentially as a single
molecule and therefore require the greatest heat energy input break the bonds of the molecule down in order to melt
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Which of the following is a reduction half-reaction?
Solution : An oxidation reduction (redox) reaction is a type of chemical reaction that involves a transfer of electrons between tow species an oxidaion reductin reaction is any chemical reaction in which the oxidation number of a molecule atom or ion changes by gaining or losing an electron
Which phenomenon explained below is an example of deposition?
Select the correct answer below:
A) Hail is formed from water droplets lifted by air currents to an altitude where they turn into pellets of ice.
B) Frost forms when cold evening temperatures convert the humidity in the air to thin layers of ice on the ground.
C) In the winter, the top few inches of a pond turn to ice.
D) The visible cloud arising from a boiling tea kettle is not actually steam, but droplets of liquid water that form as the
steam cools in the air.
Answer:
b
Explanation:
deposition is when water turns from gas to solid. b is the only one that fits
Deposition is frost forms when cold evening temperatures convert the humidity in the air to thin layers of ice on the ground.
What is deposition?Deposition is a process that involves collection of large mass or when mean distance between molecules are reduced. It can also be explained as gathering of substances together to form a larger mass.
Therefore, the phenomenon explained in the given example about deposition is frost forms when cold evening temperatures convert the humidity in the air to thin layers of ice on the ground.
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0. When measuring tert-butyl alcohol for this experiment, a student first weighs an empty graduated cylinder, then pours 15 mL of the alcohol into the graduated cylinder and weighs the cylinder again. He records the amount of alcohol used as the difference in these two masses. What is wrong with this method
Answer:
Both have solutions in the graduated cylinder.
Explanation:
Recording the amount of alcohol used as the difference between two masses is the wrong method used for measuring tert-butyl alcohol for the experiment. For measuring tert-butyl alcohol for this experiment, the student has to measure the two masses when both the graduated cylinders has solution of tert-butyl alcohol not when one of it is empty (having no tert-butyl alcohol ).
The wrong aspect is that the liquid didn't need to be weighed. Instead the volume should have been recorded with the aid of the graduated cylinder.
What is a Graduated cylinder?This is a cylinder with marked readings and is used to measure the volume of liquids in the laboratory.
The graduated cylinder will accurately measure the amount of alcohol used due to it being volatile and the mass fluctuating during the measurement.
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Which substance has the highest boiling point?
Select the correct answer below:
A) ethyl ether
B) ethyl alcohol
C) water
D) these all have the same boiling point
Answer:
D) these all have the same boiling point
cesium-131 has a half life of 9.7 days. what percent of a cesium-131 sample remains after 60 days?
Explanation:
From the question given above, the following data were obtained:
Half-life (t½) = 9.7 days
Time (t) = 60 days
Percentage remaining after 60 days =?Next, we shall determine the number of half-lives that has elapsed. This can be obtained as follow:
Half-life (t½) = 9.7 days
Time (t) = 60 days
Number of half-lives (n) =?
n = t / t½
n = 60 / 9.7Finally, we shall determine the percentage remaining. This can be obtained as follow:
Let the original amount be N₀
Let the amount remaining be N
Number of half-lives (n) = 60 / 9.7
N = N₀ / 2ⁿ
Divide both side by N₀
N/N₀ = 1/2ⁿ
N/N₀ = 1 / 2⁽⁶⁰÷⁹•⁷⁾
N/N₀ = 0.0137
Multiply by 100 to express in percentage
N/N₀ = 0.0137 × 100
N/N₀ = 1.37%Therefore, the percentage remaining after 60 days is 1.37%
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Cho biết độ tan của NH4Cl trong nước ở 20oC và 70oC lần lượt là 37,2 g/100 gam nước và 60,2 gam/100 g nước. Hòa tan 166,8 gam NH4Cl vào 400 gam nước ở 70oC thu được dung dịch X. Sau đó, hạ nhiệt độ dung dịch X xuống 20oC. Tính khối lượng (gam) NH4Cl kết tinh lại trong X?
Answer: Hợp chất CTHH 0 °C 10 °C 20 °C 30 °C 40 °C 50 °C 70 °C
Actini(III) hydroxide Ac(OH)3 0,0022
Amonia NH3 1176 900 702 565 428 333 188
Amoni azua NH4N3 16 25,3 37,1
View 42 more rows
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PLEASE HELP ASAP
A total of 132.33g C3H8 is burned in 384.00 g O2. Use the following questions to determine the amounts of products formed.
• How many grams of CO2 and H2O will be produced? (2 points)
b. If the furnace is not properly adjusted, the products of combustion can include other gases, such as CO and unburned hydrocarbons. If only 269.34 g of CO2 were formed in the above reaction, what would the percent yield be? (2 points)
What information does the first quantum number of an electron give?
A. The sublevel that the electron is in
B. The specific orbital the electron is in
C. The energy level the electron is in
D. The spin that the specific electron has
Answer:
с
Explanation:
the first quantum number of an electron gives the information about the energy level the electron is in
The information first quantum number of an electron give is the energy level the electron is in.
What are quantum numbers?Quantum numbers is a set of symbols which gives idea about the position of electron present inside an atom.
First quantum number is denoted by symbol 'n' which gives idea about the number of shell or energy level in which electron is present.The sublevel that the electron is in is the second quantum number denoted by symbol 'l'.The specific orbital in which electron is present is denoted by symbol 'm' and it is the third quantum number.The spin that the specific electron has is the forth quantum number and denoted by symbol 's'.Hence first quantum number of electron gives ideal about the energy level.
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A skydiver slows down from 65 m/s to 5 m/s by opening the parachute. If this
takes 0.75 seconds, what is the skydiver's acceleration?
A. 45 m/s2 up
B. 80 m/s2 up
C. 45 m/s2 down
D. 80 m/s2 down
Answer:
D. -80m/s^2
Explanation:
V = u + at
5 = 65 + a (0.75)
0.75a = -60
a = -60/0.75
a = -80m/s^2
Therefore, is decelerating at 80m/s^2
Answer:
[tex]\boxed {\boxed {\sf D. \ 80 \ m/s^2 \ down}}[/tex]
Explanation:
We are asked to find the acceleration of a skydiver. Acceleration is the change in velocity over the change in time, so the formula for calculating acceleration is:
[tex]a= \frac{v_f-v_i}{t}[/tex]
The skydiver was initially traveling 65 meters per second, then he slowed down to a final velocity of 5 meters per second. He slowed down in 0.75 seconds.
[tex]\bullet \ v_f = 5 \ m/s \\\bullet \ v_i= 65 \ m/s \\\bullet \ t= 0.75 \ s[/tex]
Substitute the values into the formula.
[tex]a= \frac{ 5 \ m/s - 65 \ m/s}{0.75 \ s}[/tex]
Solve the numerator.
[tex]a= \frac{-60 \ m/s}{0.75 \ s}[/tex]
Divide.
[tex]a= -80 \ m/s^2[/tex]
The acceleration of the skydiver is -80 meters per second squared or 80 meters per second squared down. The skydiver is slowing down or decelerating, so the acceleration is negative or down.
g An aqueous solution of nitric acid is standardized by titration with a 0.137 M solution of calcium hydroxide. If 19.0 mL of base are required to neutralize 21.8 mL of the acid, what is the molarity of the nitric acid solution
Answer:
M of HNO₃ is 0.119M
Explanation:
A basic concept of titration is that in equivalence point:
mmoles of acid = mmoles of base
We have data from base and we only have data from volume of acid.
In a case our titration is a strong acid against a strong base.
We apply formula:
M of acid . Vol of acid = M of base . Vol of base
M of acid . 21.8 mL = 0.137M . 19 mL
M of acid = (0.137M . 19 mL) / 21.8 mL
M of acid = 0.119 M
When we neutralize all the titrant we reach the equivalence point.
At this point, pH = 7
2HNO₃ + Ca(OH)₂ → Ca(NO₃)₂ + 2H₂O
A 1 liter solution contains 0.370 M hypochlorous acid and 0.493 M sodium hypochlorite. Addition of 0.092 moles of barium hydroxide will: (Assume that the volume does not change upon the addition of barium hydroxide.)
In the original solution you have the mixture of a weak acid (Hypochlorous acid) and its conjugate base (Sodium hypochlorite). That is a buffer.
The barium hydroxide will react with hypochlorous acid. If this reaction cause the complete reaction of hypochlorous acid, the buffer break its capacity and the pH change in several units. In this case:
The addition of barium hydroxide will raise the pH slightly because the buffer still working.
The initial moles of those species are:
Hypochlorous acid:
[tex]1L * \frac{0.370mol}{1L} = 0.370 moles[/tex]
Sodium hypochlorite:
[tex]1L * \frac{0.493mol}{1L} = 0.493 moles[/tex]
Now, a strong acid as barium hydroxide (Ba(OH)₂) reacts with a weak acid as hypochlorous acid (HClO) as follows:
Ba(OH)₂ + 2HClO → Ba(ClO)₂ + 2H₂O
For a complete reaction of 0.092 moles of barium hydroxide are required:
[tex]0.092 moles Ba(OH)_2*\frac{2mol HClO}{1molBa(OH)_2} = 0.184 moles HClO[/tex]
As there are 0.370 moles, the moles of HClO after the reaction are:
0.370 moles - 0.184 moles = 0.186 moles of HClO will remain
As you still have hypochlorite and hypochlorous acid you still have a buffer.
Thus, the pH will raise slightly because the amount of acid is decreasing and slightly because the buffer can keep the pH.
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Calculate [H3O+] for pH 1.86. Steps please.
Answer:
[H₃O⁺] = [H⁺] = 10^-pH = 10⁻¹°⁸⁶ = 0.0138M in [H⁺]
Explanation:
By definition pH = -log[H⁺] => [H⁺] = 10^-pH = 10⁻¹°⁸⁶ = 0.0138M in [H⁺]
Using your calculator ... I am using a TI-30XA scientific calculator.
=> start by entering the number 1.86 => then press the (+/-) function => this will insert a negative symbol => -1.86,=> next find button with "2nd" printed on face (on some calculators the button is in yellow); press this button to change to 'secondary mode',=> find the symbol (10ˣ) ... the button below this symbol is usually the 'log' button, then press it => the answer of interest will show in the display window. => ...Depending on the calculator, the answer may show as 0.0138, or 1.38x10⁻², or 1.38E-2 (=1.38 x 10⁻²). It is the user's job to insert dimensional units into answer of interest => 0.0138M, or 1.38 x 10⁻²M, or 1.38E-2M.
1.38E-2 which is 1.38 x 10⁻².
what is valency of an atom?
The number of replaceable electrons in an atom is called its valency.
Examples
Monovalent - HydrogenDivalent - OxygenValency = 8 - Number of electron in last shell [When number of electrons in last shell > 4]Valency = Number of electron in last shell [When number of electrons in last shell < 4]Thanks !
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Answer:
the combining capacity if an atom is know as valency.
the property of an element that determines the number of other atimd with an aton if the element can combine.
How many nitrate ions are present in the following aqueous solution?
5.08 L of a solution containing 2.68 x 1021 formula units of lithium nitrate per liter.
When you have the number, determine its log (base 10) and enter that value with 3 decimal places
Answer:
22.1
Explanation:
Step 1: Calculate the number of formula units of lithium nitrate
A 5.08 L solution contains 2.68 × 10²¹ formula units per liter.
5.08 L × 2.68 × 10²¹ formula units/1 L = 1.36 × 10²² formula units
Step 2: Calculate the number of nitrate ions
Lithium nitrate dissociates completely in water according to the following equation.
LiNO₃(aq) ⇒ Li⁺(aq) + NO₃⁻(aq)
The molar ratio of LiNO₃ to NO₃⁻ is 1:1. The number of nitrate ions is 1/1 × 1.36 × 10²² = 1.36 × 10²².
Then,
log (1.36 × 10²²) = 22.1
The number of nitrate ions are present in the following aqueous solution is 13.6x10²¹, and log(base 10) value of this is 22.2.
What are strong electrolytes?
Those salts which are completely dissociate into their ions in the solution form will known as strong electrolyte.
Lithium nitrate is a strong electrolyte and it shows complete dissociation as:
LiNO₃ → Li⁺ + NO₃⁻
Given that,
1 liter of solution containing = 2.68 x 10²¹ formula unit
5.08 L of solution containing = 5.08 x 2.68 x 10²¹ = 13.6x10²¹ formula unit
So, number of nitrate ion in given solution = 13.6x10²¹ formula unit
Log(13.6x10²¹) = 22.1
Hence, required values are 13.6x10²¹ and 22.1.
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Avogradro's number is the number of particles in one gram of carbon- 12 atom true or false?
Answer:
True
Explanation:
The value of the mole is equal to the number of atoms in exactly 12 grams of pure carbon-12. 12.00 g C-12 = 1 mol C-12 atoms = 6.022 × 1023 atoms • The number of particles in 1 mole is called Avogadro's Number (6.0221421 x 1023).
At a constant temperature, a sample of gas occupies 1.5 L at a pressure of 2.8 ATM. What will be the pressure of this sample, in atmospheres, if the new volume is 0.92 L?
Using boyles law
[tex]\boxed{\sf v\propto \dfrac{1}{p}}[/tex]
[tex]\\ \sf\longmapsto P_1V_1=P_2V_2[/tex]
[tex]\\ \sf\longmapsto P_2=\dfrac{P_1V_1}{V_2}[/tex]
[tex]\\ \sf\longmapsto P_2=\dfrac{2.8\times 1.5}{0.92}[/tex]
[tex]\\ \sf\longmapsto P_2=\dfrac{4.2}{0.92}[/tex]
[tex]\\ \sf\longmapsto P_2=4.56atm[/tex]
[tex]\\ \sf\longmapsto P_2\approx 4.6atm[/tex]
Answer:
[tex]\boxed {\boxed {\sf 4.6 \ atm}}[/tex]
Explanation:
We are asked to find the new pressure given a change in volume. We will use Boyle's Law, which states the volume of a gas is inversely proportional to the pressure. The formula for this law is:
[tex]P_1V_1= P_2V_2[/tex]
Initially, the gas occupies 1.5 liters at a pressure of 2.8 atmospheres.
[tex]1.5 \ L * 2.8 \ atm = P_2V_2[/tex]
The volume is changed to 0.92 liters, but the pressure is unknown.
[tex]1.5 \ L * 2.8 \ atm = P_2* 0.92 \ L[/tex]
We are solving for the final pressure, so we must isolate the variable P₂. It is being multiplied by 0.92 liters. The inverse operation of multiplication is division, so we divide both sides by 0.92 L.
[tex]\frac {1.5 \ L * 2.8 \ atm}{0.92 \ L} = \frac{P_2* 0.92 \ L}{0.92 \ L}[/tex]
[tex]\frac {1.5 \ L * 2.8 \ atm}{0.92 \ L}= P_2[/tex]
The units of liters cancel each other out.
[tex]\frac {1.5 * 2.8 \ atm}{0.92 }=P_2[/tex]
[tex]\frac {4.2}{0.92} \ atm= P_2[/tex]
[tex]4.565217391 \ atm = P_2[/tex]
The original measurements of pressure and volume have 2 significant figures, so our answer must have the same. For the number we calculated, that is the tenths place. The 6 in the hundredth place tells us to round the 5 up to a 6.
[tex]4.6 \ atm \approx P_2[/tex]
The pressure is approximately 4.6 atmospheres.
Please guys please answer this
Answer:
1. Because the rules will keep you safe it prevents you from getting hurt.
2.i) don't taste chemical
ii) Always wear protective gears
iii) be careful with tool
iv) wear protective gloves
Explanation:
help everyone get out quickly
Determine the rate of reaction based on the data below:
75-
rate of reaction = y
hydrogen produced (cm)
х
y
25
50
75
100
125
time (seconds)
Answer:
75
Explanation:
is the answer for your question
What is represented by a straight line on a graph?
o the sum of the independent and dependent variables
O only the independent variable
O only the dependent variable
o the relationship between independent and dependent variable
1 2
3
4
5
Answer:
the relationship between independent and dependent variable
Explanation:
A straight line or linear graph is one of the ways to represent a given data. It shows the relationship between two given set of data; one called the independent variable is plotted on the x-axis (horizontal) while the other called the dependent variable is plotted on the y-axis (vertical).
The straighter the line is, the stronger the relationship between the two variables and vice versa. Hence, the straight line in the graph represents the relationship between independent and dependent variable.
state function and non state function
Answer:
State functions represent quantities or properties of a thermodynamic system, while non-state functions represent a process during which the state functions change. For example, the state function PV is proportional to the internal energy of an ideal gas, but the work W is the amount of energy transferred as the system performs work.
Explanation:
Which chemical can remove color of red/Pink phenol and make it clear like water transparent?
When 1 mole of CO(g) reacts with H2O(l) to form CO2(g) and H2(g) according to the following equation, 2.80 kJ of energy are absorbed. CO(g) + H2O(l)CO2(g) + H2(g) Is this reaction endothermic or exothermic? _________ What is the value of q? kJ
Aspirin that has been stored for a long time may give a vinegar like odour and give a purple colour with FeCl3. What reaction would cause this to happen
?.
Answer:
See explanation
Explanation:
The IUPAC name of aspirin is 2-Acetoxybenzoic acid. It is composed of an acetoxy moiety and a benzoic acid moiety.
The compound can be hydrolysed under prolonged storage conditions to yield acetic acid which causes the vinegar like odour.
Also, one of the products of this hydrolysis bears a phenol group which reacts with FeCl3 to give a purple color.
how many moles of oxygen atoms are present in 0.4 moles of oxygen gas
Answer:
Each molecule of O2 is made up of 2 oxygen atoms. So 1 mole of O2 molecules is made up of 2 moles of oxygen atoms. Therefore 1 mole of oxygen gas contains 2 moles of oxygen atoms. And 0.4 moles of oxygen gas contains 0.8 moles of oxygen atoms.
There are 0.8 moles of oxygen atoms in 0.4 moles of oxygen gas.
Oxygen gas (O₂) consists of two oxygen atoms bonded together. Therefore, to determine the number of moles of oxygen atoms present in a given amount of oxygen gas, we can simply multiply the number of moles of oxygen gas by the number of oxygen atoms per molecule, which is 2.
Given that we have 0.4 moles of oxygen gas, we can calculate the number of moles of oxygen atoms as follows:
Number of moles of oxygen atoms = Number of moles of oxygen gas × Number of oxygen atoms per molecule
= 0.4 moles × 2
= 0.8 moles
Therefore, there are 0.8 moles of oxygen atoms present in 0.4 moles of oxygen gas.
This calculation is based on the stoichiometry of oxygen gas, which indicates that each molecule of O₂ contains two oxygen atoms. By considering the mole ratio between oxygen gas and oxygen atoms, we can determine the number of moles of oxygen atoms in a given quantity of oxygen gas.
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why does D2O
have a higher boiling point than H2O
Answer:
deuterium is heavier isotope of hydrogen need
high weight of atom will lead to higher boiling point
explain chlorination of methane
Answer:
Methane and chlorine
If a mixture of methane and chlorine is exposed to a flame, it explodes - producing carbon and hydrogen chloride. This is not a very useful reaction! The reaction we are going to explore is a more gentle one between methane and chlorine in the presence of ultraviolet light - typically sunlight. This is a good example of a photochemical reaction - a reaction brought about by light.
CH4+Cl2+energy→CH3Cl+HCl(3.4.2)
The organic product is chloromethane. One of the hydrogen atoms in the methane has been replaced by a chlorine atom, so this is a substitution reaction. However, the reaction doesn't stop there, and all the hydrogens in the methane can in turn be replaced by chlorine atoms.
Substitution reactions happen in which hydrogen atoms in the methane are replaced one at a time by chlorine atoms. You end up with a mixture of chloromethane, dichloromethane, trichloromethane and tetrachloromethane.
I hope this help you!:)
Explanation:
A filament for a light bulb needs to conduct electricity. Which of the elements listed below might be useful as a light bulb filament? Explain your thinking.
A. Tungsten, W
B. Sulfur, S
C. Bromine, Br
Answer:
A. tungsten
Explanation:
Tungsten is a material which high melting point ie. does not melt easily incase of high temperature
Answer:
option(A):Tungsten
Explanation:
tungsten has highest melting point.
e. Which of the following is a mixture? i. Water ii. Hydrogen iii. Air iv. Iron
water is known as the mixture
Answer:
iv. Iron
water is not a mixture
hydrogen is the simplest element
air is pure
Determine the effect each given mutation would have on the rate of glycolysis in muscle cells.
a. loss of binding site for fructose 1 ,6-bisphophate in pyruvate kinase.
b. loss of allosteric binding site for ATP in pyruvate kinase.
c. loss of allosteric binding site for AMP in phosphofructokinase.
d. loss of regulatory binding site for ATP in phosphofructokinase.
1. Increase
2. decrease
3. No effect
Answer:
a. Decrease
b. Increase
c. Increase
d. No effect
Explanation:
Glycolysis is present in muscle cells which converts glucose to pyruvate, water and NADH. It produces two molecules of ATP. Cellular respiration produces more molecules of ATP from pyruvate in mitochondria. Glycolysis increases in pyruvate kinase.
a. Loss of binding site for fructose 1,6-bisphosphate in pyruvate kinase: Decrease
b. Loss of allosteric binding site for ATP in pyruvate kinase: No effect
c. Loss of allosteric binding site for AMP in phosphofructokinase: Increase
d. Loss of regulatory binding site for ATP in phosphofructokinase: Increase
A. An important substrate in the glycolysis pathway is fructose 1,6-bisphosphate. It stimulates pyruvate kinase, an essential enzyme in glycolysis. The amount of pyruvate kinase that is activated will decrease if the fructose 1,6-bisphosphate binding site in pyruvate kinase is eliminated. As a result the rate of glycolysis in the muscle cells will probably decrease.
B. The allosteric ATP binding site of pyruvate kinase controls how active the enzyme is. However, pyruvate kinase is not significantly regulated by ATP in muscle cells. Therefore, it is unlikely that deletion of the ATP-binding allosteric site in pyruvate kinase would have no effect on the rate of glycolysis in muscle cells.
C. The rate-limiting enzyme in glycolysis, phosphofructokinase, is activated from all forms by AMP. It increases the rate of glycolysis by stimulating the activity of phosphofructokinase. If the allosteric binding site for AMP is eliminated, phosphofructokinase activation will be reduced. As a result, the rate of glycolysis in muscle cells will decrease.
D. Phosphofructokinase is inhibited allosterically by ATP. It regulates the rate of glycolysis by a feedback mechanism. High ATP concentrations cause phosphofructokinase to bind to its regulatory site, limiting its activity and delaying glycolysis. If the regulatory binding site for ATP is eliminated, the inhibitory action of ATP on phosphofructokinase would be lost. As a result, muscle cells will glycolysis at a faster rate.
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