Calculating concentration?

Question

I have to calculate the concentration of the NaOH solution I used in a titration lab from my data. So my volume was 0.02830L and the amount of moles was 0.1025mol. Then I divided the moles over litres to get 3.6mol/l. But in the titration it was the volume of NaOH used to titrate 10.00ml of 0.15M H2C2O4 so now I'm confused because it took 28.30mL to titrate the oxalic acid. Would I have to include the other amounts (10.00ml of 0.15M H2C2O4) and if yes how would I do that?

Answer 1

If you are sure that the volume was 0.02830L and the amount of NaOH was 0.1025mol, then the concentration of the NaOH solution is 3.622 M. Up to this point you are correct, but also pay attention to the significant figures!
So you understand the unit M is the same as unit mol/L. Now you have NaOH concentration!
Now, pay attention!
The reaction is: 2NaOH + H2C2O4 ==> 2H2O + Na2C2O4
That means it takes 2 mol of NaOH to react with one mol H2C2O4.
If you had 10.00ml of 0.15M H2C2O4, that is (0.01L)*(0.15M)=0.0015mol of H2C2O4, that requires 0.003 mol NaOH to titrate to the right endpoint!
If you used up all 28.30mL NaOH to titrate, you have used way toooo much NaOH (0.1025mol). You may only need less than half mL of your NaOH to reach the right end-point. That means your NaOH concentration is way tooooooo high!