01-25-2011, 01:39 PM
01-25-2011, 01:41 PM
The concentration of the HCl solution is (log)^-1(2) = 0.01M
You want to make it pH 2.5 which has a concentration of (log)^-1(2.5) = 0.00316M
concentration = no of moles*volume
c = n/v
you are going to add x Litres of water to a solution that contains 0.5*.01 = 0.005 moles of HCl
so 0.00316 = .005/(0.5 + x)
0.5 + x = 0.005/0.00316 = 1.582L
x = 1.582 - 0.5 = 1.082L
You want to make it pH 2.5 which has a concentration of (log)^-1(2.5) = 0.00316M
concentration = no of moles*volume
c = n/v
you are going to add x Litres of water to a solution that contains 0.5*.01 = 0.005 moles of HCl
so 0.00316 = .005/(0.5 + x)
0.5 + x = 0.005/0.00316 = 1.582L
x = 1.582 - 0.5 = 1.082L