Questions: At the equivalence point for the titration of HCN with KOH, the pH is expected to be A 7 B greater than 7 C less than 7

Transcript text: Work - Aktiv Chemistry ktiv.com Question 1 of 15 At the equivalence point for the titration of HCN with KOH , the pH is expected to be A 7 B greater than 7 C less than 7 Search

Solution

Solution Steps

Step 1: Understanding the Titration Reaction

In the titration of hydrocyanic acid (HCN) with potassium hydroxide (KOH), we are dealing with a weak acid (HCN) and a strong base (KOH). The reaction can be represented as:

\[ \text{HCN} + \text{KOH} \rightarrow \text{KCN} + \text{H}_2\text{O} \]

Step 2: Analyzing the Equivalence Point

At the equivalence point, all the HCN has reacted with KOH to form potassium cyanide (KCN). The solution now contains the salt KCN, which can hydrolyze in water:

\[ \text{CN}^- + \text{H}_2\text{O} \rightleftharpoons \text{HCN} + \text{OH}^- \]

The cyanide ion (\(\text{CN}^-\)) is the conjugate base of the weak acid HCN and will react with water to produce hydroxide ions (\(\text{OH}^-\)), making the solution basic.

Step 3: Determining the pH at the Equivalence Point

Since the solution contains a basic salt (KCN) at the equivalence point, the pH will be greater than 7. This is because the production of \(\text{OH}^-\) ions from the hydrolysis of \(\text{CN}^-\) increases the pH.