Explanation:
noble gases are useful let's take for instance helium which is used in balloons. they are used to form inert atmosphere and they are used also to deter chemical reaction.
Calculate the mass percent of KCl in a 0.35 m solution of KCl in water. Assume that the density of water is 1.00 g/mL.
Answer:
Mass percent of KCl is 2.61 %
Explanation:
Our solute is KCl
Our solvent is water
m means molality (moles of solute in 1kg of solvent)
1 kg = 1000 g
0.35 m means that 0.35 moles of KCl are contained in 1000g of solvent
We determine mass of solute: 0.35 mol . 74.55 g/mol = 26.09 g
Total mass of solution is: mass of solute + mass of solvent
26.09 g + 1000 g = 1026.09 g
Mass percent of KCl = (mass of KCl/ mass of solution) . 100
(26.09 / 1026.09) . 100 = 2.61 %
What is the major product in this reaction
Answer:
I think option A is right answer
At 298 K, ∆H = -314 kJ/mol and ∆S = -0.372 kJ/(K•mol). What is the Gibbs free energy of the reaction?
Answer:
-203 kJ/mol
Explanation:
Step 1: Given data
Standard enthalpy of the reaction (ΔH°): -314 kJ/molStandard entropy of the reaction (ΔS°): -0.372 kJ/K.molAbsolute temperature (T): 298 KStep 2: Calculate the standard Gibbs free energy of the reaction (ΔG°)
We will use the following expression.
ΔG° = ΔH° - T × ΔS°
ΔG° = (-314 kJ/mol) - 298 K × (-0.372 kJ/K.mol) = -203 kJ/mol
By convention, when ΔG° < 0, the reaction is spontaneous.
explain in brief how some bacteria cause tooth cavities
Answer:
because some bacteria change the ph of the teeth and leads to tooth cavitiew
Calculate percent yield when you start with 0.78 grams of camphor and end with 0.23 grams of iso/borneol. The molecular weight of camphor is 152.23 g/mol, and the molecular weight of iso/borneol is 154.25 g/mol.
Answer:
29.1%
Explanation:
First we convert 0.78 g of camphor to moles, using its molar mass:
0.78 g ÷ 152.23 g/mol = 0.00512 mol camphorThen we convert 0.23 g of isoborneol to moles, using its molar mass:
0.23 g ÷ 154.25 g/mol = 0.00149 mol isoborneolFinally we calculate the percent yield:
0.00149 mol / 0.00512 mol * 100% = 29.1%What type of reaction?
Write the symbol for every chemical element that has atomic number greater than 70 and atomic mass less than 185.2
Answer:
HF...Ta... W....Lu...
Poly(ethylene terephthalate) (PET), which has glass transition (Tg) and crystalline melting (Tm) temperature of 69 and 267 °C, respectively, can exist in a number of different states depending upon temperature and thermal history. Thus, it is possible to prepare materials that are semicrystalline with amorphous regions that are either glassy or rubbery and amorphous materials that are glassy, rubbery or melts. Consider a sample of PET cooled rapidly from 300 °C (state A) to room temperature. The resulting material is rigid and perfectly transparent (state B). The sample is then heated to 100 °C and maintained at this temperature, during which time is gradually becomes translucent (state C). It is then cooled to room temperature, where it is again observed to be translucent (state D).
Answer:
Following are the solution to the given points:
Explanation:
For point A:
The sample cooking (PET) is between 300°C and room temperature.Now in nature, the substance is exceedingly stiff.Samples of PET up to 100°C were heated and stayed on equal footing.Now it has cooled off the same sample below 100° C and we may see how it is again TRASNEPARENT in nature.For point B:
In point 3, the mixture was added to 100°C, which implies that the granular material flows and deforms, enabling it to become elongated. This is termed solid-state crystalline such that grains are flexible, but this material contaminates numerous little crystalline that has spheres when we cool down in point 4 polymers. It forms therefore an unstructured solid, which then in point 4 is higher in particles and less pliable in orderly atoms.
For point C:
In point 2, the specimen gets forced at room temperature to organize a huge molecule in an ordinary and crystal fashion and therefore is transparent due to highly crystalline atoms in point 2 of the PET sample.
In point 4, however, we notice how amorphous, firm but not crystalline develops. It's why light tends to disperse over many cereal limits, since many microscopic crystallines, therefore dispersion, PET in point 4 is translucent.
cual es la masa atomica del hidrogeno
El hidrógeno es el elemento químico de número atómico 1, representado por el símbolo H. Con una masa atómica de 1.00784 u es el más ligero de la tabla periódica de los elementos. Por lo general, se presenta en su forma molecular, formando el gas diatómico H₂ en condiciones normales.
For a gas sample containing equimolar amounts of carbon monoxideand heliumat 300 K, heliumhas _____________average speed and _____________ average kinetic energy compared tocarbon monoxidegas.a.a lower; the same b. the same; the same c. a higher; the same d. a higher; higher
Answer:
Option C (a higher; the same) is the appropriate response.
Explanation:
Given:
Temperature,
T = 300 K (both [tex]N_2[/tex] and [tex]H_2[/tex])
As we know,
Average speed of a molecule,
⇒ [tex]\bar v=\sqrt{\frac{8RT}{\pi M} }[/tex]
Thus, the average speed of [tex]N_2[/tex] will be lower as its molar mass is greater than [tex]H_2[/tex].
Now,
⇒ [tex]Average \ kinetic \ energy = \frac{3}{2} \ KT[/tex] (not depend on molar mass)
Hence, it will be the same.
The other three alternatives aren't connected to the scenario given. So the above is the correct answer.
Identify the highest energy molecular process that occurs when a molecule absorbs a microwave photon.
The question is incomplete, the complete question is;
Identify the highest energy molecular process that occurs when a molecule absorbs a microwave photon
a) electronic excitation
b) bond breakage
c) molecular vibration
d) molecular rotation
Answer:
molecular rotation
Explanation:
Microwaves are part of the electromagnetic spectrum. They are lower energy, lower frequency radiation.
When molecules absorb infrared radiation, they transition between the rotational states of the molecule.
Hence, the highest energy molecular process that occurs when a molecule absorbs a microwave photon is molecular rotation.
How many electrons are shown in the following electron
configuration: 1s22s22p63s 23p64s23d104p65s24d105p66s2 ?
Express your answer numerically as an integer.
Answer:
1s22s22p6
Explanation:
Neon is an element in the periodic table and has an atomic number of 10, which means it has 10 protons in its nucleus and thus since the number of protons and electrons is the same then it has 10 electrons.
Therefore, it has 2 electrons in the first energy shell and 8 electrons in the second energy shell. To elaborate further, the first shell has a single s-sub shell that contains a single s-orbital that can hold two electrons. The second energy shell has a single s-sub-shell whose s-orbital will occupy 2 electrons, and also has a p-orbital which can hold 6 electrons, making the second shell to have 8 electrons.
The reversible reaction: 2SO2(g) O2(g) darrow-tn.gif 2SO3(g) has come to equilibrium in a vessel of specific volume at a given temperature. Before the reaction began, the concentrations of the reactants were 0.060 mol/L of SO2 and 0.050 mol/L of O2. After equilibrium is reached, the concentration of SO3 is 0.040 mol/L. What is the equilibrium concentration of O2
Answer:
[tex][O_2]_{eq}=0.030M[/tex]
Explanation:
Hello there!
In this case, according to the given information, it turns out possible for us to solve this problem by firstly writing out the mathematical expression for the concentration of oxygen at equilibrium, given the initial one and the change due to the reaction extent:
[tex][O_2]_{eq}=0.050M-x[/tex]
Whereas [tex]x[/tex] can be found considering the equilibrium of SO3:
[tex][SO_3]_{eq}=2x=0.040M[/tex]
Which means:
[tex]x=\frac{0.040M}{2} =0.020M[/tex]
Thus, the equilibrium concentration of oxygen gas turns out:
[tex][O_2]_{eq}=0.050M-0.020M=0.030M[/tex]
Regards!
it takes 513 kj to remove a mole of electrons from the atoms at the surface of a piece of metal. how much energy does it take to remove a single electron from n atom at the surface of the metal
Answer:
The right solution is "[tex]8.5\times 10^{-19} \ joule[/tex]".
Explanation:
As we know,
1 mole electron = [tex]6.023\times 10^{23} \ no. \ of \ electrons[/tex]
Total energy = [tex]513 \ KJ[/tex]
= [tex]513\times 1000 \ joule[/tex]
For single electron,
The amount of energy will be:
= [tex]\frac{513\times 1000}{(6.023\times 10^{23})}[/tex]
= [tex]8.5\times 10^{-19} \ joule[/tex]
dentify the correct formula for the following ionic compounds. - sodium chloride - magnesium chloride - calcium oxide - lithium phosphide - aluminum sulfide - calcium nitride A. SCl B. LiP 3 C. AlS D. Li 3P E. CaN F. CaO G. Ca 3N 2 H. MgCl 2 I. NaCl J. CaO 2 K. CaN 2 L. LiP M. MnCl 2 N. Al 2S 3 O. AlS 3
Explanation:
The chemical formula of an ionic compound can be written by using the symbols of the respective cations and anions.
The overall charge on the molecule should be zero.
Hence, the total charge of cations=total charge of anions.
The symbols of the given molecules are shown below:
sodium chloride ---- NaCl
magnesium chloride ---[tex]MgCl_2[/tex]
calcium oxide ---- CaO
lithium phosphide----[tex]Li_3P[/tex]
aluminum sulfide ----- [tex]Al_2S_3[/tex]
calcium nitride---- [tex]Ca_3N_2[/tex]
Identify the oxidation half-reaction for this reaction:
Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g)
A. Fe2+ + 2e → Fe(s)
O B. H2(g) → 2H+ + 2e
O C. Fe(s) → Fe2+ + 2e
O D. 2H+ + 2e → H2(9)
Answer:
Fe(s)->Fe2+2e-
Explanation:
A.p.e.x
The oxidation half-reaction for the given reaction is Fe(s) → Fe²⁺ + 2e⁻ Hence, Option (C) is correct
What is Oxidation reaction ?Oxidation reaction is a chemical reaction which can be described as follows ;
Addition of oxygen Removal of hydrogen Loss of ElectronAddition of electronegative atomRemoval of Electropositive elementIn the given reaction ;
Fe(s) + 2HCl(aq) → FeCl₂(aq) + H₂(g)
Fe at RHS got converted to Fe²⁺ state at LHS which shows the gain of electron by Fe with in the reaction.
Therefore,
The oxidation half-reaction for the given reaction is Fe(s) → Fe²⁺ + 2e⁻ Hence, Option (C) is correct
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A molecule of acetone and a molecule of propyl aldehyde are both made from 3 carbon atoms, 6 hydrogen atoms, and 1 oxygen atom. The molecules differ in their arrangement of atoms. How do formulas for the two compounds compare? Both compounds have the same molecular formula, but have unique structural formulas. Both compounds have unique molecular formulas and structural formulas. Both compounds have the same structural formula, but have unique molecular formulas.
Explanation:
The structures of both acetone and propanal are shown below:
In the formula of propanal there is -CHO functional group at the end.
In acetone -CO- group is present in the middle that is on the second carbon.
The molecular formula is C3H6O.
Both have same molecular formula but different structural formulas.
_________one moleculetwo moleculesone moletwo moles of H2(g) reacts with _________one moleculetwo moleculesone moletwo moles of F2(g) to form _________one moleculetwo moleculesone moletwo moles of HF(g).
Answer:
The reaction between hydrogen and fluorine.
Explanation:
The balanced chemical equation of the reaction is:
[tex]H_2(g)+F_2(g)->2HF(g)[/tex]
From the balanced chemical equation, it is clear that:
1 mole of [tex]H_2[/tex] gas reacts with one mole of [tex]F_2(g)[/tex] and forms 2 moles of HF(g).
A gas at 74°C is heated to 120°C so there is pressure reaches 1.79 ATM. What is its initial pressure?
Explanation:
here's the answer to your question
In the process of preparing liquid air for fractional distillation, one fraction will be separated as a solid. What is the chemical name of this fraction?
Answer:
carbon dioxide CO₂
Explanation:
Each gas has a characteristic boiling point. You can separate a random sample of gases by gradually cooling the sample until each component gas liquifies. Some compounds, such as CO₂ never liquify. Instead, they turn directly into solids.
The fraction that will be separated as a solid in the process of liquefaction of air is carbon dioxide.
What is sublimation?
Sublimation is the process of changing the material from its solid to gaseous form without it being liquid, according to physics. An illustration is the evaporation of dry ice, which is frozen carbon dioxide, at typical atmospheric pressure and temperature. Vapour pressure and temperature correlations cause the phenomena.
Food is freeze-dried to preserve it by sublimating water from it while it is frozen under a strong vacuum. Phase is a term used in thermodynamics to describe an amount of matter that is chemically and physically uniform or homogeneous, can be mechanically isolated from a nonhomogeneous mixture, and may consist of a single material or a combination of substances.
The three basic phases of matter are solid, liquid, and gas (vapor), however additional phases, including crystalline, colloid, glassy, amorphous, and plasma, are thought to exist.
Therefore, during the liquefaction of air, the gas that will be separated as a solid is carbon dioxide.
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the carbon tetrachloride molecule CCI 4 is
Answer:
is a nonpolar molecule with polar bonds
2, classify the following molecules as polar or non polar.
A,CH4 B,CHcl C,Co2 D,H2O2 E,BCl3 F,H2S
A. CH4= NON POLAR
B. CH3cl= POLAR
C. CO2= NON POLAR
D. H2O2= POLAR
E. BCl3= NON POLAR
F. H2S= SLIGHTLY POLAR
A chemical reaction was carried out by mixing 25 g of pure CaCO3 and 0.75 mole of pure HCl to give CaCl2, H2O and CO2. a. Which one is the limiting reactant and why? b. Calculate the mass of CaCl2 produced. c. How many number of water molecules are formed? d. Calculate the volume of CO2 gas liberated at STP. e. What mass of NaOH is required to absorb the whole CO2 produced in the reaction?
hola, esta pregunta es bastante difícil pero está bien, no lo sé, lo siento :) :)
All the options are solved and answer is written below
What is a Chemical Reaction ?A reaction between two or more compounds to form products made after chemical change is called a chemical reaction.
It is given that
A chemical reaction was carried out by mixing 25 g of pure CaCO₃ and 0.75 mole of pure HCl
CaCl₂ , H₂O and CO₂ are the products obtained.
CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O
Mole ratio CaCO₃ : HCl : CaCl₂ : H₂O = 1 : 2 : 1 : 1
Molar mass of CaCO₃ = 100 g/mol
Molar mass of HCl = 36.5 g/mol
Molar mass of H₂O = 18 g/mol
Molar mass of CaCl₂= 110.98 g/mol
Moles of CaCO₃ = 25/100 = 0.25 moles
Moles of HCl present = 0.75 mole
For 0.25 moles of CaCO₃ 0.5 moles of HCl is required , as the moles of HCl is present in excess therefore
a. CaCO₃ is the limiting reactant
b. mass of CaCl₂ produced
Moles of CaCl₂ produced = 0.25 moles
1 mole means 110.98 gm
0.25 mole means 0.25* 110.98 = 27.74 gm
c. moles of water molecules formed
for 0.25 moles of CaCO₃ 0.25 moles of water will be formed
d.Volume of Co produced at STP
PV = nRT
P= 1 atm
V=?
R = 0.0821 atm L/K/mol
V = 0.25 * 0.0821 * 273 /1
V = 5.6 liter
e. The mass of NaOH required to absorb CO₂ produced in the reaction
Ratio of NaOH:CO₂ = 2 :1
0.5 moles will be required , i.e.
0.5 *40
20 grams of NaOH will be required.
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A sample of oxygen gas has a volume of 89.6 L at STP. How many moles of oxygen gas are present ?
Answer:
89,6/22,4 =4(mol)
Explanation:
There are approximately 1.089 moles of oxygen gas present in the sample at STP.
At STP (Standard Temperature and Pressure), the conditions are defined as follows:
Temperature (T) = 0 degrees Celsius = 273.15 Kelvin
Pressure (P) = 1 atmosphere (atm) = 101.325 kPa = 1013.25 hPa
Now, to find the number of moles of oxygen gas (O2) present in the sample, we can use the ideal gas law:
PV = nRT
Where:
P = pressure (in atm)
V = volume (in liters)
n = number of moles
R = ideal gas constant = 0.0821 L.atm/(mol.K)
T = temperature (in Kelvin)
Given:
V = 89.6 L (volume at STP)
T = 273.15 K (STP temperature)
Let's plug in the values and solve for n (number of moles):
n = PV / RT
n = (1 atm) × (89.6 L) / (0.0821 L.atm/(mol.K) × 273.15 K)
n = 1.089 moles
So, there are approximately 1.089 moles of oxygen gas present in the sample at STP.
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An electrolysis reaction is
A)
exothermic.
B)
hydrophobic.
C)
spontaneous.
D)
non-spontaneous.
Answer:
the electrolysis reaction is a non- spontaneous reaction
Explanation:
Since electrons flow from it, the anode in an electrolytic cell is positive, while the cathode is negative when electrons flow into it. The device functions like a galvanic cell in that direction. In an electrolytic cell, an external voltage is applied and that is what causes a non spontaneous reaction
When 4.41g of phosphoric acid (H3PO4) react with 9.25g of barium hydroxide, water and insoluble barium phosphate form. [T/I-7] a. Write and balance the chemical equation.
Answer:
2 H₃PO₄(aq) + 3 Ba(OH)₂(aq) ⇒ Ba₃(PO₄)₂(s) + 6 H₂O(l)
Explanation:
Let's consider the unbalanced equation that occurs when phosphoric acid reacts with barium hydroxide to form water and barium phosphate. This is a neutralization reaction.
H₃PO₄(aq) + Ba(OH)₂(aq) ⇒ Ba₃(PO₄)₂(s) + H₂O(l)
We will balance it using the trial and error method.
First, we will balance Ba atoms by multiplying Ba(OH)₂ by 3 and P atoms by multiplying H₃PO₄ by 2.
2 H₃PO₄(aq) + 3 Ba(OH)₂(aq) ⇒ Ba₃(PO₄)₂(s) + H₂O(l)
Finally, we will get the balanced equation by multiplying H₂O by 6.
2 H₃PO₄(aq) + 3 Ba(OH)₂(aq) ⇒ Ba₃(PO₄)₂(s) + 6 H₂O(l)
Determine whether the reaction will be spontaneous at high temperatures only, at low temperatures only, at all temperatures, or no temperatures. (HINT: Use your chemical sense and your real-world knowledge to predict the signs of delta Hrxn & delta Srxn)
4Fe(s) + 3O2(g) ----> 2Fe2O3(s) [rust]
Circle one:High T, Low T, All T, No T
Answer:
The rusting of iron is spontaneous at low temperatures.
Explanation:
The given chemical reaction is:
4Fe(s) + 3O2(g) ----> 2Fe2O3(s) [rust]
The rusting of iron is a chemical reaction in which iron reacts with oxygen in presence of moisture and forms iron oxide.
This reaction takes place in a faster rate when there is low temperatures in the atmosphere.
When temperature is low, the moisture in the atmosphere is more and hence, rate of rusting is more.
5. A beam of photons with a minimum energy of 222 kJ/mol can eject electrons from a potassium surface. Estimate the range of wavelengths of light that can be used to cause this phenomenon. Show your calculations with units of measure (dimensional analysis) and briefly explain your reasoning.
Answer: The range of wavelengths of light that can be used to cause given phenomenon is [tex]8.953 \times 10^{21} m[/tex].
Explanation:
Given: 222 kJ/mol (1 kJ = 1000 J) = 222000 J
Formula used is as follows.
[tex]E = \frac{hc}{\lambda}[/tex]
where,
E = energy
h = Planck's constant = [tex]6.625 \times 10^{-25} Js[/tex]
c = speed of light = [tex]3 \times 10^{8} m/s[/tex]
Substitute the values into above formula as follows.
[tex]E = \frac{hc}{\lambda}\\222000 J = \frac{6.625 \times 10^{-34}Js \times 3 \times 10^{8} m/s}{\lambda}\\\lambda = 8.953 \times 10^{21} m[/tex]
Thus, we can conclude that the range of wavelengths of light that can be used to cause given phenomenon is [tex]8.953 \times 10^{21} m[/tex].
Classify the following as either solutions or colloids. If a colloid, name the type of colloid and identify both the dispersed and the dispersing phases.
a. glucose in water
b. smoke in air
c. carbon dioxide in air
d. milk
Answer:
a. glucose in water( solution)
b. smoke in air (colloids)
c. carbon dioxide in air (solution)
d. milk( colloids)
Explanation:
A solution is said to be formed when a solute dissolves in a solvent to form a homogeneous mixture. The solute particles are less than 10^-9m in size. Familiar solutions are those where the solute are dissolved in a liquid solvent. When the liquid water, the solution is known as an aqueous solution. A typical example is (glucose in water). In some other cases, the apparent solution of a solute in a solvent is accompanied by a chemical reaction and this is often known as a chemical reaction. A typical example is (carbon dioxide in air).
Colloids are also known as false solutions. Here, the individual solute particles are larger than the particles of the true solution, but not large enough to be seen by the naked eye. When a light beam is placed beside a beaker containing a colloid, the light rays of the beam can be clearly seen. This shows that it exhibits the Tyndall effect while a solution dosent exhibit such.
In a colloid, the liquid solvent is more appropriately know as the DISPERSION medium while the solid solute particles constitute the DISPERSED substance. This can either be solid, liquid or gas.
For example:
--> smoke in air : Dispersion medium is gas while the dispersed substance is solid.
--> milk: Dispersion medium is liquid while the dispersed substance is liquid.
0.50 g of hydrogen chloride (HCl) is dissolved in water to make 4.0 L of solution. What is the pH of the resulting hydrochloric acid solution
Explanation:
Given the mass of HCl is ---- 0.50 g
The volume of solution is --- 4.0 L
To determine the pH of the resulting solution, follow the below-shown procedure:
1. Calculate the number of moles of HCl given by using the formula:
[tex]number of moles of a substance=\frac{given mass of the substance}{its molecular mass}[/tex]
2. Calculate the molarity of HCl.
3. Calculate pH of the solution using the formula:
[tex]pH=-log[H^+][/tex]
Since HCl is a strong acid, it undergoes complete ionization when dissolved in water.
[tex]HCl(aq)->H^+(aq)+Cl^-(aq)[/tex]
Thus, [tex][HCl]=[H^+][/tex]
Calculation:
1. Number of moles of HCl given:
[tex]number of moles of a substance=\frac{given mass of the substance}{its molecular mass}\\=0.50g/36.5g/mol\\=0.0137mol[/tex]
2. Concentration of HCl:
[tex]Molarity of HCl=\frac{number of moles of HCl}{its molar mass}\\=\frac{0.0137 mol}{4.0 L} \\= 0.003425 M[/tex]
3. pH of the solution:
[tex]pH=-log[H^+]\\=-log(0.003425)\\=2.47[/tex]
Hence, pH of the given solution is 2.47.
