Ideal Gas | Numerical Problem |

Q. Find the number of moles of molecules present in 50 mL of an ideal gas exerting a pressure of 770 mm at 25 ⁰ . ( R = 0.082 L atm mol ^-1 K^-1 ).

Answer :

Given , volume of gas (V) = 50 mL = 0.05 L

Pressure of gas (P ) = 770 mm = 1.01 atm

Temperature ( T) = 25⁰ C = ( 25 + 273) = 298 K

Universal gas constant ( R ) = 0.082 L atm mol^-1 K^-1

No of moles (n) = ?

Now again we know that ,

PV = nRT

n = PV / RT

n = (1.01 * 0.05 ) / (0.082 * 298 ) = 2.066 * 10 ^-4 mol

Hence , number of moles of the gas is 2.066 * 10 ^-4 mol.