Name _____________________________ Class _______ _____ / 62 pts

CHEMISTRY TEST chapter 11, gases and stoichiometrY

You may use your mole map, periodic table and calculator.

Multiple Choice (2 pts each)

1. When Gay-Lussac's law of combining volumes holds, which of the following can be expressed in ratios of small whole numbers?

a. pressure before and pressure after reaction

b. volumes of gaseous reactants and products

c. Kelvin temperatures

d. molar masses of products and reactants

2. At constant temperature and pressure, gas volume is directly proportional to the

a.	number of moles of gas.	c.	density of the gas at STP.
b.	molar mass of the gas.	d.	rate of diffusion.

3. According to Avogadro's law, 1 L of H₂(g) and 1 L of O₂(g) at the same temperature and pressure

a.	have the same mass.	c.	contain 1 mol of gas each.
b.	have unequal volumes.	d.	contain equal numbers of molecules.

4. The standard molar volume of a gas at STP is all of the following except

a.	the volume occupied by 1 mol of the gas.
b.	the volume occupied by one molar mass of the gas.
c.	22.4 L.
d.	22.4 g.

5. When pressure, volume, and temperature are known, the ideal gas law can be used to calculate

a. the chemical formula. c. molar amount.

b. the ideal gas constant. d. compressibility.

6. In the equation H₂(g) + Cl₂(g) ® 2HCl(g), one volume of hydrogen yields how many volumes of hydrogen chloride?

a. 1 c. 3

b. 2 d. 4

7. The ratios of the volumes of the gaseous reactants and products in a chemical reaction at constant temperature and pressure can be determined from the

a.	formulas.	c.	subscripts in the balanced equation.
b.	coefficients in the balanced equation.	d.	gas constant.

8. In the reaction 2 C + O₂(g) ® 2 CO(g), what is the volume ratio of O₂ to CO?

a.	1:1	c.	1:2
b.	2:1	d.	2:2

9. What is the volume occupied by 1 mol of oxygen at STP?

a. 11.2 L c. 22.4 L

b. 16.0 L d. 32.0 L

10. Gay-Lussac’s law of combining volumes applies only to gas volumes

a. measured at constant temperature and pressure. c. that equal 22.4 L

b. that equal 1 L. d. measured at 0°C.

Problems: Show ALL your work, pay attention to units, and use for the ideal gas law constant.

11. Write the formula for the ideal gas law. (3 pts)

12. Calculate the number of grams in 5.40 L of chlorine gas (Cl₂) at STP. (5 pts)

13. What is the pressure exerted by 1.2 mol of a gas with a temperature of 20.0ºC and a volume of 9.5 L? (5 pts)

14. A gas sample with a mass of 0.686 g is collected at 27.0ºC and 0.951 atm. The volume is 350. mL. What is the molar mass of the gas? (6 pts)

15. Methane (CH₄) undergoes complete combustion to produce carbon dioxide and water vapor.

a. Write the balanced equation for this reaction. (include states of matter) (3 pts)

b. If 50 L of methane at STP are burned, what volume of water vapor will be produced at STP? (5 pts)

16. What mass of sulfur must be used to produced 14.89 L of gaseous sulfur dioxide at STP according the

following equation? (6 pts)

S_{8 (s)} + 8 O_{2 (g)} ® 8 SO_{2 (g)}

17. Liquid carbon disulfide reacts with oxygen gas to produce the gases carbon dioxide and sulfur dioxide.

a. Write the balanced equation for this reaction. (include states of matter) (3 pts)

b. If 64.2 grams of oxygen are used in the reaction, how many liters of sulfur dioxide are produced at 295 K and 0.921 atm? (6 pts)