Question

A sample of gas occupies 555mL at 175 cm Hg and a temperature of 37.0C. What is the new volume (in mL) at STP?

Answer 1

Answer: The new volume at STP is 1125.43 mL.

Explanation:

STP conditions:

Pressure of the gas is 760 mmHg and temperature of the gas is 273 K

To calculate the volume when temperature and pressure are changed, we use the equation given by combined gas law. The equation follows:

$\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}$

where,

$P_1,V_1\text{ and }T_1$ are the initial pressure, volume and temperature of the gas

$P_2,V_2\text{ and }T_2$ are the final pressure, volume and temperature of the gas

We are given:

Conversion factor:  1 cm = 10 mm

$P_1=175cmHg=1750mmHg\\V_1=555mL\\T_1=37^oC=[37+273]=310K\\P_2=760mmHg\\V_2=?mL\\T_2=273K$

Putting values in above equation, we get:

$\frac{1750mmHg\times 555mL}{310K}=\frac{760mmHg\times V_2}{273K}\\\\V_2=1125.43mL$

Hence, the new volume at STP is 1125.43 mL.