11-19-2018, 03:05 PM

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.

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.