In this week\'s experiment you will determine the molar mass of carbon dioxide b

Question

In this week's experiment you will determine the molar mass of carbon dioxide by measuring the mass of an Erlenmeyer flask full of the gas. The following calculations are intended to familiarize you with the general procedure:

The mass of an empty Erlenmeyer flask and stopper was determined to be 43.72 grams. When filled with distilled water, the mass was303.6 grams. The atmospheric pressure was measured to be 0.9647 atm, the room temperature was 24.00oC. At this temperature, the vapor pressure of water is 22.40 torr -- but assume a 50% relative humidity as outlined in the procedure for this experiment.

1.What is the number of moles of air in the flask?

Moles of air in the flask =  mol

2.If the average molar mass of the gases present in air is 28.960 g mol-1, what is the mass of air in the flask?

Mass of air in the flask =  grams

3. What would be the mass of carbon dioxide in the flask? In this case the CO2 will be saturated with water vapor so assume 100% humidity as outlined in the experiment.

Mass of carbon dioxide =  grams

4. What would be the mass of the flask (and stopper) when filled with carbon dioxide gas?

Mass of flask and stopper filled with CO2 gas =  grams

Explanation / Answer

1.

PV = nRT

n = PV/RT

Now,

P = Atmospheric pressure - V.P of water * R.H

P = 0.9647 atm - 22.40 torr * 0.5

P = 0.9647 atm - 11.2 torr      ( Now 11.2 torr = 0.0147 atm)

P = 0.9647 atm - 0.0147 atm

P = 0.95 atm

Mass of water = mass of filled flask - mass of empty flask = 303.6 - 43.72 g = 259.88 g

Volume = 259.88 * 1 g/cm^3 = 259.88 cm^3 = 259.88 x 10^-3 L

T = 273.15 + 24 = 297.15 K

n = PV/RT = (0.95 atm * 259.88 x 10^-3 L) / (0.0821 L-atm/mol-K * 297.15 K)

n = 0.01 moles

2.

mass of air = moles of air * molar mass of air

mass of air = 0.01 mol * 28.96 g/mol

mass of air = 0.2896 g

3.

Mass of CO2 = moles of air * mass of CO2

Mass of CO2 = 0.01 mol * 44 g/mol = 0.44 g

4.

mass of flask and stopper with CO2 gas = mass of CO2 + weight of empty flask and stopper

mass of flask and stopper with CO2 gas = 0.44 g + 43.72 g = 44.16 g

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.