Here's how to calculate the grams in a mole of hydrogen chloride (HCl):

1. Find the molar mass of HCl:

* Hydrogen (H): 1.008 g/mol

* Chlorine (Cl): 35.45 g/mol

Add the molar masses together: 1.008 g/mol + 35.45 g/mol = 36.458 g/mol

2. One mole of any substance is equal to its molar mass in grams.

Therefore, there are 36.458 grams in one mole of hydrogen chloride (HCl).