According to reaction, Mg _ ( s ) +2 HCl _ ( aq ) MgCl _ 2( aq ) + H _ 2( ~g ) Calculate the mass of Mg required to liberate 4.48 dm ^3 H ₂ at STP. ( . Molar mass of Mg =24 ~g ~mol ⁻¹ )

Step-by-step solution

Number of moles of a gas (n) = Volume of gas at STP 22.4 dm ^3 ~mol ⁻¹ n = 4.48 dm ^3 22.4 dm ^3 ~mol ⁻¹ =0.2 ~mol Mg _ ( s ) +2 HCl _ ( aq ) MgCl ₂+ H _ 2( ~g ) 1 ~mol Mg 1 ~mol H ₂ gas Mg required to liberate 0.2 ~mol H ₂ gas =0.2 ~mol =0.2 24=4.8 ~g