Chapter 12 Problem QUIZ
KEY

1. The volume of a gas is 250 mL at 340.0 kPa of pressure.  What will the volume be when the pressure is reduced to 50.0 kPa, assuming the temperature remains constant?

P1V1 = P2V2

V2 = V1 x P1/P2

250 mL  x   340.0 kPa/50.0 kPa =

1700 mL

2. A balloon filled with helium has a volume of 30.0 L at a pressure of 100 kPa and a temperature of 15.0o C.  What will the volume of the balloon be if the temperature is increased to 80.0oC and the pressure remains constant?

V1 / V2  =  T1 / T2

V2 = V1 x T2/T1

30.0L x  353K/288K =

34.3 L

3. A gas has a volume of 590 mL at a temperature of -55oC.  What volume will the gas occupy at 30.0o C?

T1 = -55oC  +  273 = 218 K

T2 = 30.0oC  +  273 = 303 K

V1 / V2  =  T1 / T2

V2 = V1 x T2/T1

590 mL  x 303K/218K =

820 mL

4. A gas occupies a volume of 140 mL at 35o C and 97 kPa.  What is the volume of the gas at conditions of STP?

T1 = 35.0oC  +  273 = 308 K

T2 = 0.0oC  +  273 = 273 K

P1V1 / T1= P2V2 / T2

V2 =  P1 x  V1 x   T2/ (T1xP2)

V2 = 97 kPa  x 140 mL x 273 K / (308K x 101 kPa) =

120 mL

5. A gas has a pressure of 710 kPa at 227oC.  What will its pressure be at 27oC if the volume does not change?

227oC = 273 = 500 K

27oC + 273 = 300 K

P1 / T1  =  P2 / T2

P2 = P1 T2 / T2

P2 = (710 kPa x 300 K)/ 500 K 

470 kPa

6. The gaseous product of a reaction is collected in a 25.0 L container at 27o C.  The pressure in the container is 300.0 kPa and the gas has a mass of 96.0 grams.  What is the formula mass of the gas?

PV = nRT

n = PV/RT

300.0 KPa x 25 L / 8.31 x 300 K =

3.0 mol

96 g / 3.0 mol = 32 g/ mol  is the formula mass

7. A mixture of gases at a total pressure of 95 kPa contains N2, CO2, and O2.  The partial pressure of the CO2 is 24 kPa and the partial pressure of the N2 is 48 kPa.  What is the partial pressure of the O2?

PO2 = Ptotal - (PCO2  +  PN2) 

95 KPa - (48KPa + 24kPa) =

23 kPa

8. The separate of uraniou-235 from uranium-238 has been carried out using gaseous diffusion.  Calculate the relative rates of diffusion of gaseous UF6 containing these isotopes.  The formula mass of UF6 containing uranium-235 is 349 amu and the formula mass of UF6 containing uranium-238 is 352 amu.

Rate235 / Rate238 =  (352)1/2  /  (349)1/2  = 1.004

The UF6  containing the U-235 diffuses 1.004 times faster.

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