Question

Which of the following solutions can be used to neutralize nitric acid?
Ca(OH)2

hydrochloric acid

H2O

lemon juice

Answer 1

Ca(OH)2 because it is a relatively strong bronsted base, so it will dissociate in water to Ca+2 and -OH, this -OH Can Bond with the H+ leading to the formation of water which is a relatively neutral compound (pH of water is usually 7 (which is a neutral pH))

Remember,
pH = -log[H+]
When you see square brackets [] it means Molarity concentration.

You will notice from this equation as H+ concentration deceases pH increases and as H+ concentration increases pH decreases.

The less H+ in the solution the higher the pH. Thus, if you have a solution of nitric acid it is going to have a low pH, as Nitric Acidis a strong acid meaning it completely dissociates in solution to form H+ Ions and NO3-).

Since Ca(OH)2 releases -OH it can eliminate the H+ released forming a neutral compound water. Thus if you add just enough Ca(OH)2 you will eliminate all the H+ in solution resulting in a pH of 7.

If you tried using water lemon juice or HCl you would just decease the pH more making the solution more acidic.

Use of H2O to neutralize would be effective at lowering the concentration of the nitric acid but it would only work because the H+ ions released would decrease in concentration because they would be diluted down in solution, you would need a lot of water to reach 7pH and in effect you are not really chemically neutralizing the nitric acid you are diluting it.