Question

A sample of dry gas weighing 2.1025 g is found to occupy 2.850 L at 22.0oC and 740.0 mm Hg. How many moles of gas are present?

Answer 1

0.11 moles of the gas are present in the sample of dry gas.

Explanation:

Data given:

mass of the gas  = 2.1025 grams

volume of the gas = 2.850 litres

temperature =  22 degrees (273.15+22) = 295.15 K

Pressure = 740 mm Hg or 0.973 atm

moles of the gas =?

R = 0.08206 atmL/Mole K

From the ideal gas law the number of moles can be calculated in the sample of dry gas. Number of moles will be determined by the pressure exerted, volume and temperature of the gas.

The formula:

PV = nRT

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

putting the values in the above equation:

n = $\frac{2.850 x 0.973}{0.08206 X 295.15}$

  = 0.11 moles

0.11 moles of the dry gas is present in the sample given.