Question

the following data were obtained in an experiment to find the molecular mass of a liquid: volume of gas: 8.352 mL Temperature: 99 C Pressure: 742 mmHg Mass of Condensed liquid: 0.0326 g Calculate the molecular mass of the liquid

Answer 1

• Lets identify the given measurements :

1. Volume =8.352mL/1000 = 0.00835L

2.Temperature = 99°C +273 = 372K

3.pressure 742mmHg = 742/760 = 0.976 atm

4 . Mass of liquid = 0.0326 g

5. R (gas constant) = 0.0821 J.mol^-1

• We are to calculate Molecular Mass (M) ,

• we know that n = given mass of element/Molecular mass of element.

Formula : PV= nRT

n = PV/RT

but n = m/M , so substituting this will be as follows :

m/M = PV/RT

∴M = m/(P*V*R*T)

= 0.0326 /( 0.976 *0.00835*0.0821*372)

= 0.0326 /0.248898

= 0.1309

∴Molecular mass of the liquid ≈0.131