# Homework Help: Chemistry: pH after adding water

1. Mar 12, 2005

### theCandyman

I am trying to find what the new concentration of $$OH^{-}$$ in a solution of potassium hydroxide (pH = 11.65) is after diluting it with water to six times the original volume. It is at 298.15 K (25 degrees Celcius).

I have found the concentration of $$H_{3}O^{+}$$ and I guessed that I just multiply the volume times six (divide the concentration by six) to find the new concentration, would this be a correct way to approach this problem?

2. Mar 13, 2005

### Sirus

$$c_{1}v_{1}=c_{2}v_{2}$$

where c is concentration and v is volume. Find the initial [OH-], then use the above formula and the information given to find the new concentration.