Suppose a solution is prepared by dissolving 15.0 g NaOH in 0.150 L of 0.250 M nitric acid. What is the final concentration of OH− ions in the solution after the reaction has gone to completion. Assume that there is no volume change when adding the grams of NaOH

Respuesta :

Answer:

2.25 M is the final concentration of hydroxide ions ions in the solution after the reaction has gone to completion.

Explanation:

Moles of NaOH = [tex]\frac{15.0 g}{40 g/mol}=0.375 mol[/tex]

Molarity of the nitric acid solution = 0.250 M

Volume of the nitric solution = 0.150 L

Moles of nitric acid = n

[tex]Molarity=\frac{Moles}{Volume(L)}[/tex]

[tex]n=0.250 M\times 0.150 L=0.0375 mol[/tex]

[tex]NaOH+HNO_3\rightarrow NaNO_3+H_2O[/tex]

According to reaction, 1 mole of nitric acid recats with 1 mole of NaOH, then 0.0375 moles of nitric acid will react with :

[tex]\frac{1}{1}\times 0.0375 mol[/tex] of NaOH

Moles of NaOH left unreacted  in the solution =

= 0.375 mol - 0.0375 mol = 0.3375 mol

[tex]NaOH(aq)\rightarrow Na^+(aq)+OH^-(aq)[/tex]

1 mole of sodium hydroxide gives 1 mol of sodium ions and 1 mole of hydroxide ions.

Then 0.3375 moles of NaOH will give :

[tex]1\times 0.3375 moles=0.3375 mol[/tex] of hydroxide ion

The molarity of hydroxide ion in solution ;

[tex]=\frac{0.3375 mol}{0.150 L}=2.25 M[/tex]

2.25 M is the final concentration of hydroxide ions ions in the solution after the reaction has gone to completion.