The balanced chemical equation for the reaction between hydrogen and chlorine is:

$$H_2 + Cl_2 -> 2HCl$$

From the equation, we can see that 1 mole of hydrogen reacts with 1 mole of chlorine to produce 2 moles of hydrogen chloride.

The molar mass of hydrogen chloride (HCl) is 36.46 g/mol.

Therefore, the mass of hydrogen chloride formed when 1 mole of hydrogen reacts with 1 mole of chlorine is:

$$2 moles HCl * 36.46 g/mol = 72.92 g HCl$$