Question

Which do you think is a better buffer (more resistant to the addition of acid and base)?

1.A solution that is 0.1M in HA and 0.01M in A.

2.A solution that is 0.01M in HA and 0.1M in A.

3.A solution that is 0.1M in HA and 0.1M in A.

4.A solution that is 0.05M in HA and 0.05M in A.

Answer 1

The most effective buffer at resisting pH changes when acid or base is added will be one with equal concentrations of a weak acid and its conjugate base. In this case, the mixture of 0.1M HA and 0.1M A is the best buffer, as it maintains near equal concentrations after acid addition and has a higher overall buffer concentration.

Step-by-step explanation:

When choosing which solution is a better buffer, it's important to consider the resistance to pH changes upon the addition of acid or base. According to buffer action principles, a solution that has about equal concentrations of a weak acid and its conjugate base, often in the form of its salt, is more effective. Upon adding 0.001 M HCl, response 3, with a mixture of 0.1M HA and 0.1M A, is the most resistant as it maintains near equal concentrations post-addition, changing from [A] to 0.099 M and [HA] to 0.101 M. Moreover, a high overall buffer concentration enhances the buffer capacity.

Answer 2

The most effective buffer against pH changes when acid or base is added is a solution with equal concentrations of the acid and its conjugate base, in this case, option 3 with both 0.1M HA and 0.1M A.

Step-by-step explanation:

A buffer is a solution that contains a weak acid and its conjugate base and is resistant to pH changes upon the addition of acid or base. When comparing the buffer solutions mentioned, the most effective buffer would be the one with equal concentrations of acid and its conjugate base. Therefore, the solution that is 0.1M in HA and 0.1M in A (option 3) would be considered the best buffer, as it is most resistant to changes in pH due to a higher buffer capacity. This is because when you add 0.001 M HCl, it would slightly adjust the concentrations of HA and A but still maintain nearly equal concentrations of the acid (HA) and its conjugate base (A), which is essential for efficient buffering.