You have a sample of 0.25 mol of unknown gas at stp. can you predict the volume of the gas, even if you don’t know the identity of the gas ? can you predict the mass of the sample ? explain.

a. 5.6 L

b. can be find without given mass or Molar mass

Explanation:

Data given:

mole of unknown gas = 0.25 mol

volume of gas = ?

mass of the sample = ?

Solution:

Yes we can find volume of the gas by using its amount of moles.

To find the volume of the gas at STP the following formula can be used

            no. of moles = volume of gas / molar volume

Rearrange the above formula

           volume of gas = no. of moles x molar volume . . . . . (1)

Where

molar mass of gas = 22.4 L/mol

Put values in equation 1

        volume of gas = 0.25 mol x 22.4 (L/mol)

       volume of gas = 5.6 L

So the volume of gas is 5.6 L.

Q. Can you predict the mass of the sample?

To find mass of the gas we must know the molar mass of gas.

if we Know the molar mass of gas the by using ideal gas equation we can find mass of unknown gas

ideal gas equation

          PV = nRT . . . . . . .(1)

where

n = m/M . . . . . . (2)

by combining equation 1 and 2 we get following equation

          PV = m/MRT . . . . . . .(3)

Now by rearranging equation 3 we can find mass of gas or Molar mass of gas. but one value must be given.