Calculate the mass and amount of hydrogen chloride that is formed when exposed to 10 g of hydrogen with chlorine

Given:
m (H2) = 10 g

To find:
m (HCl) -?
n (HCl) -?

Decision:
1) Write the reaction equation:
H2 + Cl2 => 2HCl;
2) Calculate the molar masses of H2 and Cl2:
M (H2) = Mr (H2) = Ar (H) * N (H) = 1 * 2 = 2 g / mol;
M (Cl2) = Mr (Cl2) = Ar (Cl) * N (Cl) = 35.5 * 2 = 71 g / mol;
3) Calculate the amount of substance H2:
n (H2) = m (H2) / M (H2) = 10/2 = 5 mol;
4) Determine the amount of substance Cl2:
n (Cl2) = n (H2) = 5 mol;
5) Calculate the mass of Cl2:
m (Cl2) = n (Cl2) * M (Cl2) = 5 * 71 = 355 g.

Answer: The mass of Cl2 is 355 g; the amount of substance is 5 mol.