Question

Calculate the total pressure in a $10.0L$ cylinder which contains $0.4g$ helium, $1.6g$ oxygen and $1.4g$ nitrogen at $27^{\circ }C$ .

• A. $0.492$ atm
• B. $49.2$ atm
• C. $4.92$ atm
• D. $0.0492$ atm

Answer 1

Answer: (A)

Number of mol of $He=\frac{0.4}{4}=0.1$
Number of mol of oxygen $=\frac{1.6}{32}=0.05$
Number of mol of nitrogen $=\frac{1.4}{28}=0.05$
Total moles in the $10.0L$ cylinder at
$27^{\circ }=(0.1+0.05)+0.05^{\circ }$
$=0.2mol$
$P_T=\frac{nRT}{V}$
$=\frac{0.2\times 0.082\times 300}{10}$
$=0.492atm$