A student conducts an experiments to determine the enthalpy of neutralization for phosphoric acid reacting with sodium hydroxide. The student combines 25.0 mL of equimolar solutions of acid and base, both having an initial temperature of 22.5 degree C, in an open polystrene calorimeter. Each solution has a density of 1.00g/mL and a specific heat of 4.18 J/g x degree C. The student collects data until a maximum temperature of 26.4 degree C is reached.

Question

Calculate the qrxn for the neutralization reaction. (What is qrxn??) and how does the student know the data collection is complete?

Answer 1

qrxn = mass water x specific heat water x (Tfinal-Tinitial)
solve for qrxn.
I don't understand the last part of the question but since phosphoric acid is H3PO4 and sodium hydroxide is NaOH, 25.0 mL each of equimolar solutions will neutralize only 1 of the H ions on H3PO4.