Steve, in an attempt to impress his girlfriend, plops 18.2 grams of sodium metal into 500 mL of concentrated phosphoric acid (density = 1.88 g/cm3) in a beaker. The reactants were both initially at 25 oC. The reaction gently produced bubbles of hydrogen and Janet was not impressed. What was the final temperature of the reaction mixture if all the heat is transferred to/from the phosphoric acid?

Question

Steve, in an attempt to impress his girlfriend, plops 18.2 grams of sodium metal into 500 mL of concentrated phosphoric acid (density = 1.88 g/cm3) in a beaker. The reactants were both initially at 25 oC. The reaction gently produced bubbles of hydrogen and Janet was not impressed. What was the final temperature of the reaction mixture if all the heat is transferred to/from the phosphoric acid?
2 H3PO4 (l) + 6 Na (s) = 2 Na3PO4 (s) + 3 H2 (g)
Thermodynamic data for phosphoric acid can be found on the National Institutes of Standards and Technology website:
webbook.nist.gov/cgi/cbook.cgi?ID=C7664382&Mask=2&Type=JANAFL&Table=on#JANAFL).