Question

A solution of hydrochloric acid, HCl(aq), is prepared by dissolving 3.7 g of HCl(g) in enough water to make 1.0 L of solution.

The pH of the solution is

Answer 1

Moles HCl = 3.7 g / 36.46 g·mol⁻¹ = 0.1015 mol.
[H+] = 0.1015 mol / 1.00 L = 0.1015 M.
pH = −log[H+] = −log(0.1015) = 0.99 ≈ 1.0.

So the pH is about 1.0.