Can somebody help me please

Question

If it takes 0.793 L of 0.9 M NaOH to neutralize 2 L of an HCl solution, what is the concentration of HCl?

 M

Answer 1

The governing chemical reaction equation is:

NaOH + HCl → NaCl + H₂O

So, we see that it takes 1 mole of NaOH to neutralize 1 mole of HCl.

A 0.9 M solution of NaOH means it has 0.9 moles/liter of NaOH. And since we have 0.793 liters of it, we have 0.9•0.793 or 0.7137 moles of NaOH.

That means 0.7137 moles of HCl was neutralized. Since we had 2L of HCl, the concentration was 0.7137/2 or a 0.35685 M solution. Since this problem only uses 1 sig fig in the givens, we need to round to 1 sig fig. So the solution was a 0.4M solution of HCl