First things first: what concentration of Ca(OH)2 do we need for pH of 9.2?
is a base, we can't use pH = -log([H3
]), but we can use pOH = -log([OH-
]), and since we know that pH + pOH = 14, we can find that for pH = 9.2 we have pOH = 4.8. Solving for hydroxide concentration, we see that [OH-
] = 10-4.8
, which gives us the required concentration of Ca(OH)2
for pH = 9.2. Is my reasoning correct here?
We can calculate the amount of Ca(OH)2
using n = m/M which yields n = 0.11 mol. Using c = n/V we can solve for V and find out the total
amount of water needed to have pH = 9.2. Then we simply subtract our initial volume from that number to get how much water we have to add.
Is this correct?