homework problem

Question

A 1.00 L flask is filled with 1.20 g of argon at 25 ∘C. A sample of ethane vapor is added to the same flask until the total pressure is 1.150 atm .
Part A
What is the partial pressure of argon, PAr, in the flask?Express your answer to three significant figures and include the appropriate units.

PAr =value........; units............

Part B
What is the partial pressure of ethane, Pethane, in the flask?
Express your answer to three significant figures and include the appropriate units.
Pethane: Value.........; units............

Answer 1

PV = nRT

n = 1.20 g Ar x 1 mol/39.95 g = 0.0300 moles

P = nRT/V = (0.0300 mol)(0.0821 Latm/Kmol)(298K)/1.00 L = 0.734 atm = P_Ar

 

Total P = P_Ar + P_ethane

P_ethane = 1.150 atm - 0.734 atm = 0.416 atm = P_ethane