Chemistry 1
HH#19.5
Gas Laws/Stoich
1. The volum e of a gas is 520 liters (L) at 750 m mH g and 20C. What volum e w ill it occupy at 610
m m H g and 70C?
2. A m ass of helium gas occupies a volum e of 100 L at 20C. If the volum e occupied by the gas is
tripled to w hat m ust the tem perature be changed in ord er to keep the pressure constant?
3. What volum e in liters w ill 2.71 m ol of H e gas occupy at STP
4. Calculate the m ass of 120 L of CO 2 gas at STP.
5. What pressure, in atm ospheres, w ill 26.0 g of H e exert w hen placed in a 3.24-L steel cylind er at
200C?
6. Calculate the d ensity of SO 2 gas at 40C and 730 m m H g.
7. H ow many m olecules of H 2S are in a 22.40-L volum e at 273.0 K and 4.000 atm ?
8. A given m ass of helium gas, w hich occupies a volum e of 2.0 L at STP w as allow ed to expand to a
volum e of 4.0-L by changing the tem perature and pressure. What w as its d ensity at the new
tem perature and pressure?
9. A volum e of 120 cm 3 (mL) of a d ry gaseous com pound , m easured at 22C and 742 m m H g, has a
m ass of 0.820 g. Calculate the approxim ate m olar m ass (m olecular m ass) of the gas.
10. A particular gas is com posed of 85.7 percent carbon and 14.3 percent hyd rogen. A sam ple
w eighing 0.560 g is found to occupy a volum e of 0.100 L at 2.00 atm and -29C.
a. What is the sim plest form ula for the gas?
b. What is the m olar m ass of the gas?
c. What is the m olecular form ula of the gas?
11. In a gaseous mixture of CH 4 and C 2H 6 there are tw ice as m any m oles of CH 4 as C 2H 6. The partial
pressure of the CH 4 is 40 m m H g. What is the partial pressure of C 2H 6?
12. A sam ple of aluminum oxid e is d ecom posed by heating to prod uce alum inum and oxygen gas. 252
m L of oxygen is collected over w ater at 24°C and 772.4 m m H g.
a. H ow many gram s of alum inum oxid e w ere d ecom posed ?
b. If the original sam ple of the alum inum oxid e w as im pure and had a m ass of 0.750 g, calculate
the percentage of alum inum oxid e in the original im pure sam ple.
1.
2.
3.
4.
5.
6.
748 L
879 K (606 °C)
60.7 L
236 g CO 2
77.9 atm
2.39 g SO 2/ L
7.
8.
9.
10.
11.
12.
4 x 6.022 x 1023 m olecules
half the original d ensity or 0.089 g H e/ L
0.820 g/ 0.00484 m ol ≈ 170 g/ m ol
a. CH 2 b. 56.1 g/ m ol c. C 4H 8
20 m m H g
a. 0.693 g Al2O 3
b. 92.4 %