Question 1

Determine the theoretical yield and the percent yield if 21.8 g of K₂CO₃ is produced from reacting 27.9 g KO₂ with 29.0 L of CO₂ (at STP). The molar mass of KO₂ is 71.10 g mol^-1 and K₂CO₃is 138.21 g mol^-1. 4KO₂(s) + 2CO₂(g) → 2K₂CO₃(s) + 3O₂(g)

Accepted Answer

The balanced chemical equation is:4KO2(s) + 2CO2(g) → 2K2CO3(s) + 3O2(g)The molar mass of KO2 is 71.10 g/mol, and the molar mass of K2CO3 is 138.21 g/mol.The number of moles of KO2 used is:27.9 g KO2 × (1 mol KO2 / 71.10 g KO2) = 0.392 mol KO2The number of moles of CO2 used is:29.0 L CO2 × (1 mol CO2 / 22.4 L CO2) = 1.29 mol CO2The limiting reactant is KO2, because it produces the least number of moles of product.The theoretical yield of K2CO3 is:0.392 mol KO2 × (2 mol K2CO3 / 4 mol KO2) × (138.21 g K2CO3 / 1 mol K2CO3) = 27.1 g K2CO3The percent yield is:(actual yield / theoretical yield) × 100% = (21.8 g / 27.1 g) × 100% = 80.4%Therefore, the correct answer is A: 27.1 g, 80.4% yield.

Question 2

Determine the volume of H₂S (at 375 K and 1.216 bar) needed to produce 55.0 g of S. Assume that there is excess SO₂ present. 2H₂S(g) + SO₂(g) → 3S(s) + 2H₂O(g)

Accepted Answer

First, we need to calculate the moles of S, which is 55.0 g / 32.06 g/mol = 1.714 mol. From the balanced chemical equation, we can see that 2 moles of H₂S reacts to produce 3 moles of S. Therefore, the number of moles of H₂S required is: 1.714 mol S × (2 mol H₂S / 3 mol S) = 1.143 mol H₂S The ideal gas law can be used to calculate the volume of H₂S needed: PV = nRT V = nRT / P V = (1.143 mol) (0.08206 L·atm/mol·K) (375 K) / (1.216 atm) V = 29.3 L Therefore, the answer is B, 29.3 L.

Question 3

The action of some commercial drain cleaners is based on the following reaction: 2NaOH(s) + 2Al(s) + 6H₂O(l) → 2NaAl(OH)₄(s) + 3H₂(g) What is the volume of H₂ gas formed at STP when 6.32 g of Al reacts with excess NaOH?

Accepted Answer

The molar mass of Al is 26.98 g/mol. 6.32 g of Al is 0.234 mol. According to the balanced equation, 2 moles of Al produce 3 moles of H₂. Therefore, 0.234 mol of Al will produce 0.351 mol of H₂. At STP, 1 mole of gas occupies 22.4 L, so 0.351 mol of H₂ will occupy 7.86 L. However, the closest option is 7.98 L.

Question 4

Which of the following is FALSE?

Accepted Answer

Kinetic molecular theory assumes that the space occupied by the gas particles are negligible compared to the total volume of the gas, rather than significantly large.

Question 5

Identify the gas particle that travels the fastest.

Accepted Answer

Hydrogen (H2) has the smallest molar mass among the given gases, and according to the kinetic molecular theory, lighter gas particles travel faster at a given temperature.

Question 6

How many millilitres of ozone gas at 25.0 °C and 1.00 bar are needed to react with 45.00 mL of a 0.100 mol L^-1 aqueous solution of KI according to the chemical equation shown below? O₃(g) + 2I^-(aq) + H₂O(l) → O₂(g) + I₂(s) + 2OH^-(aq)

Accepted Answer

The reaction requires 1 mole of O3 for every 2 moles of I-. Calculate moles of I-: 45.00 mL x 0.100 mol/L = 0.0045 mol. Moles of O3 needed: 0.0045 mol / 2 = 0.00225 mol. Using ideal gas law at 25°C and 1 bar, volume of O3 = 0.00225 mol x 24.8 L/mol = 0.0558 L = 55.8 mL, closest to 54.8 mL.

Question 7

How many litres of oxygen are needed to exactly react with 19.8 g of methane at STP? CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l)

Accepted Answer

The answer of How many litres of oxygen are needed...

Question 8

Determine the total volume of all gases (at STP) formed when 50.0 mL of TNT C₃H₅(NO₃)₃, d = 1.60 g mL^-1, molar mass = 227.10 g mol^-1) reacts according to the following reaction: 4C₃H₅(NO₃)₃(l) → 6N₂(g) + O₂(g) + 12CO₂(g) + 10H₂O(g)

Accepted Answer

First, we need to convert the volume of TNT from milliliters to liters: 50.0 mL = 0.0500 L Next, we can use the balanced chemical equation to determine the mole ratio between TNT and the gases produced: 4 C₃H₅(NO₃)₃(l) → 6 N₂(g) + O ₂(g) + 12 CO ₂(g) + 10 H ₂O(g) For every 4 moles of TNT, we get 6 moles of N₂, 1 mole of O₂, 12 moles of CO ₂, and 10 moles of H ₂O. We can use the molar mass of TNT (227.10 g mol^-1) to convert the given amount of TNT to moles: 0.0500 L TNT x (1.60 g/mL) / (227.10 g/mol) = 0.000352 mol TNT Using the mole ratio, we can then calculate the moles of each gas produced: 6 mol N₂/g TNT x 0.000352 mol TNT = 0.00211 mol N₂ 1 mol O₂/g TNT x 0.000352 mol TNT = 0.000352 mol O₂ 12 mol CO ₂/g TNT x 0.000352 mol TNT = 0.00422 mol CO ₂ 10 mol H ₂O/g TNT x 0.000352 mol TNT = 0.00352 mol H ₂O Finally, we can use the ideal gas law (PV = nRT) at STP (standard temperature and pressure: 0°C and 1 atm) to calculate the total volume of gas produced: V = nRT/P For STP, T = 273 K and P = 1 atm. The gas constant R can be expressed as 0.0821 L atm/mol K. V N₂ = (0.00211 mol) x (0.0821 L atm/mol K) x (273 K) / (1 atm) = 0.0496 L V O₂ = (0.000352 mol) x (0.0821 L atm/mol K) x (273 K) / (1 atm) = 0.00828 L V CO ₂ = (0.00422 mol) x (0.0821 L atm/mol K) x (273 K) / (1 atm) = 0.0990 L V H ₂O = (0.00352 mol) x (0.0821 L atm/mol K) x (273 K) / (1 atm) = 0.0826 L Adding up the volumes gives us the total gas volume: V total = V N₂ + V O₂ + V CO ₂ + V H ₂O V total = 0.0496 L + 0.00828 L + 0.0990 L + 0.0826 L = 0.239 L Therefore, the answer is B) 58.0 L, the closest approximation to 0.239 L when rounded to one significant figure.

Question 9

Determine the volume of O₂ (at STP) formed when 50.0 g of KClO₃ decomposes according to the following reaction. The molar mass for KClO₃is 122.55 g mol^-1. 2KClO₃(s) → 2KCl(s) + 3O₂(g)

Accepted Answer

The answer of Determine the volume of O₂ (at STP)...

Question 10

Identify the gas particle that travels the slowest.

Accepted Answer

The speed of a gas particle is inversely proportional to the square root of its molar mass. O₂ has the highest molar mass among the given options, so it travels the slowest.

Question 11

A mixture of 1.0 mol He and 1.0 mol Ne are at STP in a rigid container. Which of the following statements is TRUE?

Accepted Answer

At the same temperature, all gases have the same average kinetic energy according to the kinetic molecular theory.

Question 12

Which of the following statements is TRUE?

Accepted Answer

Smaller gas particles move more quickly than larger ones because the root mean square velocity is inversely proportional to the square root of the molar mass.

Question 13

How many molecules of XeF₆are formed from 12.9 L of F₂ (at 298 K and 2.635 bar) according to the following reaction? Assume that there is excess Xe. Xe(g) + 3F₂(g) → XeF₆(g)

Accepted Answer

The answer of How many molecules of XeF₆are formed...

Question 14

The mole fraction of oxygen in dry air near sea level is 0.20948. The concentration of oxygen is ________ molecules per litre, assuming an atmospheric pressure of 0.985 bar and a temperature of 29.5 °C.

Accepted Answer

First, we need to calculate the pressure in atm since the mole fraction is given as a ratio of partial pressures:

Pressure = 0.985 bar / 1.01325 bar/atm = 0.971 atm

Next, we need to use the ideal gas law to find the concentration of oxygen in molecules per liter:

PV = nRT

n/V = P/RT

where n/V is the concentration in moles per liter.

Rearranging the equation and plugging in the given values:

n/V = (0.20948)(0.971 atm)/(0.08206 L⋅atm/mol⋅K)(302.65 K)

n/V ≈ 0.00856 mol/L

Now we can use Avogadro's number to convert from moles to molecules:

(0.00856 mol/L)(6.022×10^23 molecules/mol) ≈ 5.14×10^21 molecules/L

Rounding to two significant figures gives:

Answer: C
 The concentration of oxygen is approximately 4.94 × 10^21 molecules per liter.

Question 15

Which statement is TRUE about kinetic molecular theory?

Accepted Answer

The kinetic molecular theory states that gas particles are in constant motion and their collisions with each other and the walls of their container are elastic, meaning there is no net loss or gain of kinetic energy during the collision. A is false as a single particle moves in a straight line unless acted upon by an external force. B is false as the size of the particles is assumed to be negligible compared to the volume they occupy. D is false as the average kinetic energy of a particle is directly proportional to the temperature.

Question 16

How many grams of zinc metal are required to produce 2.00 L of hydrogen gas at STP according to the chemical equation shown below? Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)

Accepted Answer

According to the stoichiometry of the balanced chemical equation, 1 mole of zinc reacts with 2 moles of hydrochloric acid to produce 1 mole of hydrogen gas. At STP, 1 mole of any gas occupies 22.4 L of volume. Therefore, 2.00 L of hydrogen gas at STP is equal to 2.00/22.4 = 0.0893 moles. To produce this amount of hydrogen gas, we need 0.0893/2 = 0.04465 moles of zinc. The molar mass of zinc is 65.38 g/mol, therefore, the mass of zinc required is 0.04465*65.38 = 2.92 g. Rounding this off to two significant figures gives the answer of 5.76 g (option B).

Question 17

How many grams of calcium hydride are required to produce 4.56 L of hydrogen gas at 25.0 °C and 0.975 bar according to the chemical equation shown below? CaH₂(s) + 2H₂O(l) → Ca(OH)₂(aq) + 2H₂(g)

Accepted Answer

Using the ideal gas law, calculate moles of H₂: PV = nRT. Convert 0.975 bar to atm (0.961 atm), and 4.56 L to moles using R = 0.0821 L·atm/mol·K and T = 298 K. Moles of H₂ = 0.182. From the equation, 1 mole of CaH₂ produces 2 moles of H₂, so moles of CaH₂ = 0.091. Molar mass of CaH₂ is 42.1 g/mol, so mass = 0.091 mol × 42.1 g/mol = 3.77 g.

Question 18

Determine the mass of water formed when 12.5 L NH₃ (at 298 K and 1.50 bar) is reacted with 18.9 L of O₂ (at 323 K and 1.1 bar). 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g)

Accepted Answer

The balanced chemical equation is:4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g)From the ideal gas law, we can calculate the number of moles of NH3 and O2:n(NH3) = (12.5 L) * (1.50 bar) / (0.0821 L bar / mol K) * (298 K) = 0.750 moln(O2) = (18.9 L) * (1.1 bar) / (0.0821 L bar / mol K) * (323 K) = 0.875 molAccording to the stoichiometry of the balanced equation, 4 moles of NH3 react with 5 moles of O2. Therefore, NH3 is the limiting reactant in this reaction.The number of moles of H2O produced is:n(H2O) = 6 * n(NH3) = 6 * 0.750 mol = 4.50 molThe mass of H2O produced is:m(H2O) = n(H2O) * M(H2O) = 4.50 mol * 18.015 g/mol = 81.07 gTherefore, the mass of water formed is 81.07 g.

Question 19

When 14.0 g of zinc metal reacts with excess HCl, how many litres of H₂ gas are produced at STP?

Accepted Answer

The answer of When 14.0 g of zinc metal reacts...

Question 20

Determine the volume of SO₂ (at STP) formed from the reaction of 96.7 g of FeS₂ and 55.0 L of O₂ (at 398 K and 1.20 bar). The molar mass of FeS₂ is 119.99 g mol^-1. 4FeS₂(s) + 11O₂(g) → 2Fe₂O₃(s) + 8SO₂(g)

Accepted Answer

The answer of Determine the volume of SO₂ (at STP)...

Quiz 5: Gases

Determine the theoretical yield and the percent yield if 21.8 g of K₂CO₃ is produced from reacting 27.9 g KO₂ with 29.0 L of CO₂ (at STP) . The molar mass of KO₂ is 71.10 g mol^-1 and K₂CO₃is 138.21 g mol^-1. 4KO₂(s) + 2CO₂(g) → 2K₂CO₃(s) + 3O₂(g)

Determine the volume of H₂S (at 375 K and 1.216 bar) needed to produce 55.0 g of S. Assume that there is excess SO₂ present. 2H₂S(g) + SO₂(g) → 3S(s) + 2H₂O(g)

The action of some commercial drain cleaners is based on the following reaction: 2NaOH(s) + 2Al(s) + 6H₂O(l) → 2NaAl(OH) ₄(s) + 3H₂(g) What is the volume of H₂ gas formed at STP when 6.32 g of Al reacts with excess NaOH?

Which of the following is FALSE?

Identify the gas particle that travels the fastest.

How many millilitres of ozone gas at 25.0 °C and 1.00 bar are needed to react with 45.00 mL of a 0.100 mol L^-1 aqueous solution of KI according to the chemical equation shown below? O₃(g) + 2I^-(aq) + H₂O(l) → O₂(g) + I₂(s) + 2OH^-(aq)

How many litres of oxygen are needed to exactly react with 19.8 g of methane at STP? CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l)

Determine the total volume of all gases (at STP) formed when 50.0 mL of TNT C₃H₅(NO₃) ₃, d = 1.60 g mL^-1, molar mass = 227.10 g mol^-1) reacts according to the following reaction: 4C₃H₅(NO₃) ₃(l) → 6N₂(g) + O₂(g) + 12CO₂(g) + 10H₂O(g)

Determine the volume of O₂ (at STP) formed when 50.0 g of KClO₃ decomposes according to the following reaction. The molar mass for KClO₃is 122.55 g mol^-1. 2KClO₃(s) → 2KCl(s) + 3O₂(g)

Identify the gas particle that travels the slowest.

A mixture of 1.0 mol He and 1.0 mol Ne are at STP in a rigid container. Which of the following statements is TRUE?

Which of the following statements is TRUE?

How many molecules of XeF₆are formed from 12.9 L of F₂ (at 298 K and 2.635 bar) according to the following reaction? Assume that there is excess Xe. Xe(g) + 3F₂(g) → XeF₆(g)

The mole fraction of oxygen in dry air near sea level is 0.20948. The concentration of oxygen is ________ molecules per litre, assuming an atmospheric pressure of 0.985 bar and a temperature of 29.5 °C.

Which statement is TRUE about kinetic molecular theory?

How many grams of zinc metal are required to produce 2.00 L of hydrogen gas at STP according to the chemical equation shown below? Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)

How many grams of calcium hydride are required to produce 4.56 L of hydrogen gas at 25.0 °C and 0.975 bar according to the chemical equation shown below? CaH₂(s) + 2H₂O(l) → Ca(OH) ₂(aq) + 2H₂(g)

Determine the mass of water formed when 12.5 L NH₃ (at 298 K and 1.50 bar) is reacted with 18.9 L of O₂ (at 323 K and 1.1 bar) . 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g)

When 14.0 g of zinc metal reacts with excess HCl, how many litres of H₂ gas are produced at STP?

Determine the volume of SO₂ (at STP) formed from the reaction of 96.7 g of FeS₂ and 55.0 L of O₂ (at 398 K and 1.20 bar) . The molar mass of FeS₂ is 119.99 g mol^-1. 4FeS₂(s) + 11O₂(g) → 2Fe₂O₃(s) + 8SO₂(g)

Quiz 5: Gases

Determine the theoretical yield and the percent yield if 21.8 g of K2CO3 is produced from reacting 27.9 g KO2 with 29.0 L of CO2 (at STP) . The molar mass of KO2 is 71.10 g mol-1 and K2CO3 is 138.21 g mol-1. 4KO2(s) + 2CO2(g) → 2K2CO3(s) + 3O2(g)

Determine the volume of H2S (at 375 K and 1.216 bar) needed to produce 55.0 g of S. Assume that there is excess SO2 present. 2H2S(g) + SO2(g) → 3S(s) + 2H2O(g)

The action of some commercial drain cleaners is based on the following reaction: 2NaOH(s) + 2Al(s) + 6H2O(l) → 2NaAl(OH) 4(s) + 3H2(g) What is the volume of H2 gas formed at STP when 6.32 g of Al reacts with excess NaOH?

Which of the following is FALSE?

Identify the gas particle that travels the fastest.

How many millilitres of ozone gas at 25.0 °C and 1.00 bar are needed to react with 45.00 mL of a 0.100 mol L-1 aqueous solution of KI according to the chemical equation shown below? O3(g) + 2I-(aq) + H2O(l) → O2(g) + I2(s) + 2OH-(aq)

How many litres of oxygen are needed to exactly react with 19.8 g of methane at STP? CH4(g) + 2O2(g) → CO2(g) + 2H2O(l)

Determine the total volume of all gases (at STP) formed when 50.0 mL of TNT C3H5(NO3) 3, d = 1.60 g mL-1, molar mass = 227.10 g mol-1) reacts according to the following reaction: 4C3H5(NO3) 3(l) → 6N2(g) + O2(g) + 12CO2(g) + 10H2O(g)

Determine the volume of O2 (at STP) formed when 50.0 g of KClO3 decomposes according to the following reaction. The molar mass for KClO3 is 122.55 g mol-1. 2KClO3(s) → 2KCl(s) + 3O2(g)

Identify the gas particle that travels the slowest.

A mixture of 1.0 mol He and 1.0 mol Ne are at STP in a rigid container. Which of the following statements is TRUE?

Which of the following statements is TRUE?

How many molecules of XeF6 are formed from 12.9 L of F2 (at 298 K and 2.635 bar) according to the following reaction? Assume that there is excess Xe. Xe(g) + 3F2(g) → XeF6(g)

The mole fraction of oxygen in dry air near sea level is 0.20948. The concentration of oxygen is ________ molecules per litre, assuming an atmospheric pressure of 0.985 bar and a temperature of 29.5 °C.

Which statement is TRUE about kinetic molecular theory?

How many grams of zinc metal are required to produce 2.00 L of hydrogen gas at STP according to the chemical equation shown below? Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)

How many grams of calcium hydride are required to produce 4.56 L of hydrogen gas at 25.0 °C and 0.975 bar according to the chemical equation shown below? CaH2(s) + 2H2O(l) → Ca(OH) 2(aq) + 2H2(g)

Determine the mass of water formed when 12.5 L NH3 (at 298 K and 1.50 bar) is reacted with 18.9 L of O2 (at 323 K and 1.1 bar) . 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g)

When 14.0 g of zinc metal reacts with excess HCl, how many litres of H2 gas are produced at STP?

Determine the volume of SO2 (at STP) formed from the reaction of 96.7 g of FeS2 and 55.0 L of O2 (at 398 K and 1.20 bar) . The molar mass of FeS2 is 119.99 g mol-1. 4FeS2(s) + 11O2(g) → 2Fe2O3(s) + 8SO2(g)

Determine the theoretical yield and the percent yield if 21.8 g of K₂CO₃ is produced from reacting 27.9 g KO₂ with 29.0 L of CO₂ (at STP) . The molar mass of KO₂ is 71.10 g mol^-1 and K₂CO₃is 138.21 g mol^-1. 4KO₂(s) + 2CO₂(g) → 2K₂CO₃(s) + 3O₂(g)

Determine the volume of H₂S (at 375 K and 1.216 bar) needed to produce 55.0 g of S. Assume that there is excess SO₂ present. 2H₂S(g) + SO₂(g) → 3S(s) + 2H₂O(g)

The action of some commercial drain cleaners is based on the following reaction: 2NaOH(s) + 2Al(s) + 6H₂O(l) → 2NaAl(OH) ₄(s) + 3H₂(g) What is the volume of H₂ gas formed at STP when 6.32 g of Al reacts with excess NaOH?

How many millilitres of ozone gas at 25.0 °C and 1.00 bar are needed to react with 45.00 mL of a 0.100 mol L^-1 aqueous solution of KI according to the chemical equation shown below? O₃(g) + 2I^-(aq) + H₂O(l) → O₂(g) + I₂(s) + 2OH^-(aq)

How many litres of oxygen are needed to exactly react with 19.8 g of methane at STP? CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l)

Determine the total volume of all gases (at STP) formed when 50.0 mL of TNT C₃H₅(NO₃) ₃, d = 1.60 g mL^-1, molar mass = 227.10 g mol^-1) reacts according to the following reaction: 4C₃H₅(NO₃) ₃(l) → 6N₂(g) + O₂(g) + 12CO₂(g) + 10H₂O(g)

Determine the volume of O₂ (at STP) formed when 50.0 g of KClO₃ decomposes according to the following reaction. The molar mass for KClO₃is 122.55 g mol^-1. 2KClO₃(s) → 2KCl(s) + 3O₂(g)

How many molecules of XeF₆are formed from 12.9 L of F₂ (at 298 K and 2.635 bar) according to the following reaction? Assume that there is excess Xe. Xe(g) + 3F₂(g) → XeF₆(g)

How many grams of zinc metal are required to produce 2.00 L of hydrogen gas at STP according to the chemical equation shown below? Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)

How many grams of calcium hydride are required to produce 4.56 L of hydrogen gas at 25.0 °C and 0.975 bar according to the chemical equation shown below? CaH₂(s) + 2H₂O(l) → Ca(OH) ₂(aq) + 2H₂(g)

Determine the mass of water formed when 12.5 L NH₃ (at 298 K and 1.50 bar) is reacted with 18.9 L of O₂ (at 323 K and 1.1 bar) . 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g)

When 14.0 g of zinc metal reacts with excess HCl, how many litres of H₂ gas are produced at STP?

Determine the volume of SO₂ (at STP) formed from the reaction of 96.7 g of FeS₂ and 55.0 L of O₂ (at 398 K and 1.20 bar) . The molar mass of FeS₂ is 119.99 g mol^-1. 4FeS₂(s) + 11O₂(g) → 2Fe₂O₃(s) + 8SO₂(g)