Unit 5 Practice Problems

 

 

1.         Convert 525 torr to Pa.

 

2.         Convert 32.0 psi to mm Hg.

 

3.         What is the volume of 0.250 moles of a gas at 75oC and 1.50 atm?

 

4.         A 25.0 g sample of CO2 is placed in an 8.00 L steel tank.   What is the pressure in torr in the tank at 45oC?

 

5.         How many moles of a gas are present in 25.0 L steel tank at 1.5 x 102 kPa and 165oC?

 

6.         At what temperature in oC would 25.0 g of NH3 in a 27 L steel tank have a pressure of 1.5 atm?

 

7.         A sample of gas in a 1.00 L cylinder-piston assembly has a pressure of 2.50 x 105 Pa at 115oC.  If the gas is cooled to room temperature (25oC) and the gas is compressed to a volume of 550 mL, what is the pressure (in SI units) of the gas.

 

8.         A sample of gas in a 35.0 L cylinder-piston assembly has a pressure of 1.40 atm at 125oC.  If the pressure on the gas increases to 3.3 atm while the volume of the gas decreases to 25.0 L, what is the temperature (oC) of the gas?

 

9.         What is the molar mass of a gas if it has a density of 2.55 g/L at 22oC and 1.25 atm?

 

10.    What is the density of NH3 (g) at 35oC and 755 torr?

 

11.    Use the following equation to answer the questions below:

 

2 C2H2 (g)  + 5 O2 (g) à  4 CO2 (g) + 2 H2O (g)

 

a)  How many moles of O2 are needed to react with 15.0 mL of C2H2 at 125oC and 1.25 atm?

b)  How many liters of CO2 (g) are produced from 15.0 grams of C2H2 (g) at STP?

c)   How many liters of CO2 (g) at 75oC and 725 torr are produced from 27.0 L of C2H2 (g) at 175oC and 850 torr?

 

12.    What is the partial pressure of He in a tank with a total pressure of 850 torr if it contains 0.500g  of He, 1.505 g O2 , and 0.732 g N2?

 

13.    At 35oC water has a vapor pressure of 42.2 torr.  What is the partial pressure of a gas if the total pressure of the gas collected over water is 1.234 atm?