A solution is prepared by dissolving 0.23 mol of nitrous acid and 0.27 mol of sodium nitrite in water sufficient to yield 1.00 L of solution. The addition of 0.05 mol of HCl to this buffer solution causes the pH to drop slightly. The pH does not decrease drastically because the HCl reacts with the present in the buffer solution. The Ka of nitrous acid is 1.36 × 10-3.A) H2OB) H3O+C) nitrite ionD) nitrous acidE) This is a buffer solution: the pH does not change upon addition of acid or base.

Complete Question

A solution is prepared by dissolving 0.23 mol of nitrous acid and 0.27 mol of sodium nitrite in water sufficient to yield 1.00 L of solution. The addition of 0.05 mol of HCl to this buffer solution causes the pH to drop slightly. The pH does not decrease drastically because the HCl reacts with the __________ present in the buffer solution. The Ka of nitrous acid is 1.36 × 10-3.

A) H2O

B) H3O+

C) nitrite ion

D) nitrous acid

E) This is a buffer solution: the pH does not change upon addition of acid or base.

The correct option is  C

Explanation:

From the question we are told that

           The number of moles of nitrous acid is  

          The number of moles of sodium nitrite is

          The volume of the solution is  

           The number of mole added is  

             The Ka for nitrous acid is  

Now looking at the question  we can see that the solution is  made up of

     A weak acid , and its salt and a strong base and this would imply that the buffer is an acidic buffer what this mean is that  the  addition of small amount of  acid to the solution would pH

   Sine Nitrite  ion is the basic component of the buffer the it then means that the HCl would react with the Nitrite