Question

The pressure of sodium vapor in a 1.0 L container is 10 torr at 1000 ^oC. How many atoms are in the container?

• A. 9.7 × 10¹⁷
• B. 7.6 × 10¹⁹
• C. 4.2 × 10¹⁷
• D. 9.7 × 10¹⁹

Answer 1

The correct option is B

7.6 × 10¹⁹

Step 1: Given parameters

The Volume of sodium vapor $V=1.0L$

The pressure of sodium vapor $P=10torr=0.0013\times 10atm=0.013atm$

The temperature of sodium vapor $T=1000°c=1273K$

Step 2: Calculation of no. of atoms

By ideal gas equation,

1. No. of moles

$n=\frac{PV}{RT}$

$n=\frac{0.013\times 1}{0.0821\times 1273}moles$

$n=1.24\times {10}^{-4}moles$
2. No. of atoms

$\therefore Numberofatoms=1.24\times {10}^{-4}\times 6.022\times {10}^{23}$

$No.ofatoms=7.6\times {10}^{19}atoms$

Thus, option B is the correct option.