Question

169cm^3 of hydrogen were collected over water at 20°c and 755 mmHg. The saturated vapour pressure of water at 20°c is 17 .5 mmHg. What will be the volume of the hydrogen at s.t.p

Answer 1

Volume of hydrogen = 169 cm³ =V₁, Temperature of hydrogen gas collected = 20^oC= T₁, Pressure of gas = 755 = P₁

At stp , Temperature = 25^oC=T₂ and Pressure = P₂= 760 mm Hg

Using ideal gas equation

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

$\frac{755×169}{293}=\frac{760×V_2}{298}$

$V_2= 170.7 cm^3$

Volume of gas at STP is =170.7 cm³