The stomach is an acidic environment. What is the concentration of H+ (in mol/L) if 6.0 g HCl is dissolved in 250 mL of water? [2 marks]?

Molar mass of HCl = (1.0 + 35.5) g/mol = 36.5 g/mol
No. of moles of H⁺ = (6.0 g) / (36.5 g/mol) = 6.0/36.5 mol
Volume of the solution = 250 mL = 0.25 L

Concentration of HCl = (6.0/36.5 mol) / (0.25 L) = 0.66 M (to 2 sig. fig.)