Question

1.) 0.54 L of CO2 is collected over water at 25oC. The total pressure in the vessel is measured to be 1.10 atm.

a. What is the pressure of CO2 in the container?

b. What mass (in g) of CO2 was collected?

c. 2.154 g of sample were used in this experiment. What percent of the sample is NaHCO3?

Answer 1

1)

PV = nRT

a)

pressure of CO2 in container:

Ptotal = Pgas + Pvapor

Pvapor = 23.8 torr

Ptotal = 1.1 = 836 torr

PCO2 = 836-23.8 = 812.2 torr --> 1.0686842 atm

b)

mass of CO2:

PV = nRT

n = PV/(RT)

n = 1.0686842*0.54/(0.082*298) = 0.02361 mol

mass = mol*MW = 0.02361*44 = 1.03884 g of CO2

c)

m = 2.154 g of sample...

1 mol of NaHCO3 --> 1 mol of CO2

so

0.02361 mol of NaHCO3 = 0.02361*84.007 = 1.983405 g of NaHCO34

% mass of NaHCO3 / total mass * 100% = 1.983405/2.154*100 = 92.0800 %