What is the pressure in a 7.50-L flask if 0.15 mol of carbon dioxide is added to 0.33 mol of oxygen? The temperature of the mixture is 48.0°C.
A)0.252 atm
B)0.592 atm
C)1.69 atm
D)3.96 atm
E)4.80 atm

Question

Quizplus · Accepted Answer

1) Convert the temperature from Celsius to Kelvin:
T = 48.0°C + 273 = 321 K

2) Use the mole fraction to find the partial pressure of each gas:
For carbon dioxide:

n(CO2) = 0.15 mol
n(total) = 0.15 mol + 0.33 mol = 0.48 mol

X(CO2) = n(CO2)/n(total) = 0.15 mol/0.48 mol = 0.3125

P(CO2) = X(CO2) * P(total)

For oxygen:

n(O2) = 0.33 mol
n(total) = 0.15 mol + 0.33 mol = 0.48 mol

X(O2) = n(O2)/n(total) = 0.6875

P(O2) = X(O2) * P(total)

3) Use the ideal gas law to find the total pressure:
PV = nRT

P(total) = n(total)RT/V = (0.48 mol)(0.0821 L·atm·K^-1·mol^-1)(321 K)/(7.50 L) = 1.69 atm

4) Plug in the partial pressures to find the total pressure:
P(CO2) = 0.3125 * 1.69 atm = 0.528 atm
P(O2) = 0.6875 * 1.69 atm = 1.162 atm

P(total) = P(CO2) + P(O2) = 0.528 atm + 1.162 atm = 1.69 atm

Therefore, the pressure in the flask is 1.69 atm.

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