You will now determine the concentration of a solution of hydrogen peroxide by a different method. Hydrogen peroxide decomposes slowly into water and oxygen at room temperature. This reaction is exothermic. When a catalyst is added, the decomposition is fast and there is a measurable temperature rise. H2O2(aq) → H2O(l) + ½O2(g) ΔΗ = −98.2 kJ mol-1 FA 1 is aqueous hydrogen peroxide, H2O2. FA 5 is manganese(IV) oxide, MnO2. (a) Method Experiment 1 • Support one of the cups in the 250 cm³ beaker. • Use the 50 cm³ measuring cylinder to add 25.0cm³ of FA 1 to the cup. • Place the thermometer in the FA 1 and tilt the cup, if necessary, so that the bulb of the thermometer is fully covered. Record the temperature in the space for results. • Add a heaped spatula measure of FA 5 to the solution in the cup. • Stir constantly until the maximum temperature is reached. Record this temperature. • Calculate and record the temperature rise. • Rinse and dry the thermometer. Experiment 2 • Support the second cup in the 250 cm³ beaker. • Use the 50 cm³ measuring cylinder to add 40.0 cm³ of FA 1 to the second cup. • Measure and record the initial temperature of the solution. • Add a heaped spatula measure of FA 5 to the solution in the second cup. • Stir constantly until the maximum temperature is reached. Record this temperature. • Calculate and record the temperature rise. Keep FA 5 for use in Question 3.