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Finding pH from mass of OH- ions - Eugene - 11-19-2018
Hi all, I have a problem for which I was given the solution but not the way it was worked out, and my answers don't match. The problem in question: Calculate the pH of a solution that contains 0.00017g OH- per 100 mL. The solution should be 9. The way I am trying to work it out (please help me figure out where I went wrong) Step 1: Convert g per 100mL into g/L: 0.00017 g per 100 mL = 0.0017 g/L Step 2: convert g/L of OH- into m/L mM of OH = 17 mass = 0.0017g Therefore: 0.0017/17 = 0.0001 Step 3: Convert into pOH -log10(0.0001) = 4 Step 4: Convert pOH into pH pH + pOH = 14. 14-4= 10. My [OH-] should be 0.00001 mol/L, but I'm ending up with 0.0001 instead. Are my conversions wrong, perhaps? Thanks for the help. |