In a coffee-cup calorimeter, 100.0 g of H2O and 8.70 grams of Na3PO4 are added. The water had an initial temperature of 24.6 oC. After the dissolution of the sodium phosphate the temperature changed to 31.3 oC.
-Was the dissolution exothermic or endothermic? Explain.
-Calculate how much heat the water lost or gained.