1.) A sample of gas with an initial volume of 34.5 L at a pressure of 765 mmHg a
ID: 1007934 • Letter: 1
Question
1.) A sample of gas with an initial volume of 34.5 L at a pressure of 765 mmHg and a temperature of 325 K is compressed to a volume of 15.4 L and warmed to a temperature of 430 K .What is the final pressure of the gas?
2.)The mass of an evacuated 265 mL flask is 143.147 g . The mass of the flask filled with 267 torr of an unknown gas at 35 C is 144.197 g . Calculate the molar mass of the unknown gas.
3.)Use the ideal gas law to complete the table
a.) Complete the 1st Row T =
b.) Complete the 2nd row V=
c.) Complete the 3rd row P =
d.) Complete the 4th row n=
4.)Consider the following reaction:
2SO2(g)+O2(g)2SO3(g)
a. What is the theoretical yield of SO3?
b. If 131.8 mL of SO3 is collected (measured at STP), what is the percent yield for the reaction?
P V n T 1.00 atm 1.11 L 0.120 mol 117 torr 0.246 mol 300 K 29.4 ml 1.78 *10^-3 25.1 C 0.565 atm 0.434 L 251 KExplanation / Answer
Q.1: Initial condition: V1 = 34.5 L, P1 = 765 mmHg, T1 = 325 K
Final condition: V2 = 15.4 L, T2 = 430 K, P2 = ?
Applying combined gas equation
P1V1 / T1 = P2V2 / T2
=> P2 = (P1xV1xT2) / (T1xV2)
=> P2 = (765 mmHg x 34.5 L x 430 K) / (325 K x 15.4 L)
=> P2 = 2267.5 mm Hg (answer)
Q.2: Given P = 267 torr = 0.35132 atm
V = 265 mL = 0.265 L
T = 35 DegC = 35 + 273 = 308 K
weight of the unknown gas, W = 144.197 g - 143.147 g = 1.05 g
Let the molecular mass be M g/mol
Applying ideal gas equation
PV = nRT = (W / M)xRT
=> M = WRT / PV
=> M = (1.05 g x 0.0821 L.atm.mol-1.K-1 x 308 K) / (0.35132 atm x 0.265 L)
=> M = 285.19 g/mol (answer)
3: (a) PV = nRT
=> T = PV/nR = (1.00 atm x 1.11 L) / (0.120 mol x 0.0821 L.atm.mol-1.K-1) = 112.7 K (answer)
(b): V = nRT / P = 39.36 L (answer)
(c) P = nRT / V = 1.48 atm
(d): n = PV/RT = 0.0119
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