What does a buffer do?

A. It resists a change in pH when H+ or OH- is added to a solution.
B. It prevents an acid-base reaction from happening.
C. It prevents an acid or base from being neutralized.
D. It prevents a salt from forming in solution.

explain how buffer solution resist chang in ph

A buffer is a solution that resists changes in pH when small amounts of acid or base are added. The correct answer is A - It resists a change in pH when H+ or OH- is added to a solution.

To understand why a buffer resists changes in pH, it's important to know how it works. A buffer typically consists of a weak acid and its conjugate base, or a weak base and its conjugate acid. When an acid or a base is added to the buffer, it reacts with the weak acid or weak base present in the buffer, forming its conjugate base or conjugate acid, respectively.

Here's how a buffer resists changes in pH:
1. If an acid is added to the buffer, it reacts with the weak base component of the buffer, converting it into its conjugate acid. This consumes the added acid and maintains the pH of the solution.
2. If a base is added to the buffer, it reacts with the weak acid component of the buffer, converting it into its conjugate base. This consumes the added base and helps maintain the pH of the solution.

By having both the weak acid and its conjugate base (or the weak base and its conjugate acid) present in the buffer, any additional acid or base introduced into the solution is neutralized by the buffer components. This allows the buffer to resist changes in pH, keeping it relatively stable.

So, in summary, a buffer resists changes in pH when H+ or OH- is added to a solution by using its weak acid and conjugate base (or weak base and conjugate acid) components to neutralize the added acid or base.