Answer to Question #109618 in General Chemistry for Jonathan

Question

A 30.21 g sample of Ar (Argon) gas has a volume of 900 mL at a temperature of 200°C.
i. Calculate the pressure using the Ideal Gas Law.
ii. Calculate the corrected pressure using the Van der Waals Equation.
a=1.336 atm×L2 b=0.03201 L
mol2 mol

Answer 1

Molar mass of Argon is 40 gms.

Thus, number of moles $= n=30.21/40=0.755$

Given : $V=0.9 L ; T=200°C=273+200=473K$

We know Gas constant $= R=0.0821 Latm mol^{-1}K^{-1}$

i. Ideal gas law : $PV=nRT \implies P=nRT/V$

$P=0.755*0.0821*473/0.9=32.577 atm$---(Answer)

ii. Van der Waals Equation : $(P+an^2/V^2)(V-nb)=nRT$

Given : $a=1.336atmL^2 mol^{-2}; b=0.03201L mol^{-1}$

Thus, $(P+(1.336*0.755^2/0.9^2))(0.9−(0.755*0.03201)=0.755*0.0821*473$

$\implies (P+0.94)(0.9-0.723)=29.319$

$\implies P=(29.319/0.177)-0.94=164.704 atm$ ---(Answer)