Answer to Question #99585 in General Chemistry for Beverlie

Question

A 107.2 mL sample of 1.00 M NaOH is mixed with 53.6 mL of 1.00 M H2SO4 in a large Styrofoam coffee cup; the cup is fitted with a lid through which passes a calibrated thermometer. The temperature of each solution before mixing is 22.05 °C. After adding the NaOH solution to the coffee cup and stirring the mixed solutions with the thermometer, the maximum temperature measured is 30.70 °C. Assume that the density of the mixed solutions is 1.00 g/mL, that the specific heat of the mixed solutions is 4.18 J/(g·°C), and that no heat is lost to the surroundings.
1. Write a balanced chemical equation for the reaction that takes place in the Styrofoam cup. Remember to include phases in the balanced chemical equation.
2. Is any NaOH or H2SO4 left in the Styrofoam cup when the reaction is over?
3. Calculate the enthalpy change per mole of H2SO4 in the reaction. answer must be in kj/mol

Answer 1

The balanced chemical equation is $2NaOH+H_2SO_4\to Na_2SO_4+H_2O$

As there are equal concentrations of $H^+$ and $OH^-$ present in the solution so there will be no $NaOH$ and $H_2SO_4$ left in the container.

Mass of $H_2SO_4$ treated in the container$=53.6\times10^{-3}\times98=5.2528g$

Enthalpy change$=mC_p\Delta T=189.925J$

Hence, enthalpy change per mole$=\frac{189.925}{53.6\times10^{-3}}=3543.38601\frac{J}{mol}$