Question

What is the concentration of h+ ions in a solution of hydrochloric acid that was prepared by diluting 35.0 ml of concentrated (11.6 m ) hcl to a final volume of 500.0 ml?

Answer 1

Hydrochloric acid ionisation is as follows;
HCl ---> H⁺ + Cl⁻
HCl is a strong base so there's complete dissociation of acid to H⁺ ions
The number of HCl moles is equivalent to number of H⁺ ions present
1 L of solution contains - 11.6 moles of H⁺ ions
In 35 ml number of moles - 11.6 mol/L / 1000 ml x 35 ml = 0.406 mol
This number of moles are dissolved in 500 ml 
therefore molarity = 0.406 mol /500 ml x 1000 ml = 0.812 M