pH of salt

[phiryn]

In lecture 1/22 for pH of a salt solution, we were given Kb. Why did we have to find Ka and use that value instead of Kb?

[606210664]

This would be if the salt acts as an acid or a base one the ion is removed (will it donate H or accept H).

[Annie 3E]

Ka is the constant for acids and Kb is the constant for basic solutions. You would have to find the appropriate constant depending on whether the salt is defined as acidic or basic. To find the appropriate constant, one can use the following equation to switch back and forth between Kb and Ka values: Ka*Kb=10^-14.