Chemistry question, reaction equation and pH?

Question

When the gas hydrogen chloride (HCl) dissolves in water it acts as a strong acid.

a) Write the reaction equation for hydrogen chloride dissolving in water.

b) Find the pH of the solution formed when 0.040 mol of hydrogen chloride gas dissolves in

0.80 litres of pure water at a temperature of 298.15 K.

(some questions might be soo easy, but I am a middle age RN and I need to help my 2 adopted kids, I forgot Physics and Chemistry as I was in school long long time ago)

Answer 1

a) HCl (g) → H+ (aq) + Cl- (aq)

Some instructors teach that hydronium ion (H3O+) is formed in acid solutions. If that is the case,

HCl (g) + H2O → H3O+ (aq) + Cl- (aq)

b) Molarity = 0.040 mol / 0.80 L = 0.050 mol/L (M)

pH = -log[H+] = -log(0.050 M) = 1.30.