Could someone please check my math for a Ph calculation.

[born2dive9702 0]

Hello Everyone

I am not a chemist nor have much experience in the formulas. I have tried to solve this and I can not get it to work out.

I am trying to find the Ph of 8.10581454g of 85% phosphoric acid in 18927.1ml of water.

Here is my math
Ok can some one please tell me if I did this right

I have 8.105807928 grams of 85% Phosphoric acid. Now Phosphoric acid has 97.995287 molecular mass

So if i divide 8.105870928 by 97.995287 I get .082716304 moles is this correct?

Then since I have 18.9271 L

So if I take .082716304 and divide by 18.9271 i get .00437 for the concentrate is this correct?

Now when I put this into the ph calculator I am getting 2.47 ph is this correct?

Please let me know what the Ph would be on this solution. 

Thank you
Brad