Question

This is a Mixed question A 101.2 mL sample of 1.00 M NaOH is mixed with 50.6 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 22.25 °C. After adding the NaOH solution to the coffee cup and stirring the mixed solutions with the thermometer, the maximum temperature measured is 31.50 °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 Part 1 (1 point) Write a balanced chemical equation for the reaction that takes place in the Styrofoam cup. Remember to include phases in the balanced chemical equation. Part 2 (1 point) Is any NaOH or H2SO4 left in the Styrofoam cup when the reaction is over? Choose one: A. No B. Yes Part 3 (1 point) Calculate the enthalpy change per mole of H2SO4 in the reaction. kJ/mol

Answer 1

part 1)

balanced chemical equation :

H2SO4 (aq) +   2 NaOH (aq)   -----------------> Na2SO4 (aq) + 2 H2O (l)

part 2)

moles of H2SO4 = 50.6 x 1 / 1000 = 0.0506

moles of NaoH = 101.2 x 1 / 1000 = 0.1012

H2SO4 (aq) +   2 NaOH (aq)   -----------------> Na2SO4 (aq) + 2 H2O (l)

    1                         2                                                  1                     2

0.0506             0.1012

no , any NaOH or H2SO4 is left in styroform cup.

both are consumed . no one is left.

part 3)

Q = m Cp dT

   = 151.8 x 4.18 x (31.50 - 22.25)

Q = 5869.3 J

delta H = - Q / n

             = - 5869 x 10^-3 / 0.0506

enthalpy change = -116 kJ/mol