posted by Fran .
If 200. mL of 2.00 M H3PO4 solution is added to 600. mL of 2.00 M NaOH solution, the resulting solution will be ____ molar in Na3PO4.
you have .2*2 moles H2PO4
you have .6*2 moles of NaOH
H3PO4 + 3NaOH>> Na3PO4 + H2O
so for each mole of acid, you need three times that amount of base.
.4moles acid, need 1.2 moles of base, but you have 1.2, which is magically just right. So, you should get .4 moles of trisodiumphosphate.
Molarity= .4 moles/(.800L+moleswater made)
moleswater made is .4 moles, or 18*.4grams, or 7.2 ml water or
molarity= .4moles/(.8072) then reduce that to three significant digits.
check my work.