Enthalpy Practice, Chemistry 161
Name______________________________
1. A reaction occurs between 30.0mL of 1.000M phosphoric acid (H3PO4) and 45.0mL of
1.000M sodium hydroxide (NaOH) base to form water and sodium phosphate. The
temperature of the mixture increases from 25.00C to 28.50C as the reaction proceeds
to completion.
s(H2O) = 4.184 J/gC
density of solution = 1.00 g/mL
q=cmT
a. Write the balanced equation for the reaction.
b. Where would you put the word ‘heat’ in your reaction above, as a reactant or as
a product? Is the reaction exothermic or endothermic?
c. How much heat (q) was produced by the reaction?
d. Calculate H in kJ/mol acid.
e. Calculate H in kJ/mol base.
f.
What is Hrxn, the Enthalpy of the reaction?
g. If 56.2 mL of 1.00M phosphoric acid were mixed with 59.6 mL of 1.00M NaOH,
how much heat would be released or gained?