Question

I recently conducted an experiment looking at the enthalpy change in a decomposition reaction of hydrogen peroxide using a catalyst (Iron (III) chloride) and am now writing a report for it. The literature states that the change in enthalpy for this reaction should be 94.6 kJ mol^-1 (exothermically), whereas our experimentation determined the enthalpy change to be 100.7 kJ mol^-1.
In the discussion section, I am discussing how the calorimeter used would not create a 'perfect' environment and would still lose some heat to it's surroundings. But what I am confused about is wouldn't the loss of heat to the surroundings mean that the experimental value be lower then 94.6 kJ mol^-1?

Answer 1

H2O2(aq) + 2 Fe 3+(aq) ------------->O2(g) + 2 Fe2+(aq) + 2 H+ (aq)

H2O2(aq) + 2 Fe2+(aq) + 2 H+ (aq)---------------> 2 H2(l) + 2 Fe3+(aq)

Lose of heat to surrounding can n't be Source of error in this case because we are getting more negative Enthalpy Change which indicates that more heat is released.The source of error can be excessive stirring which lead to increase of kinetic energy which increase temperature

It can be due to faulty measurement of Temperature of water.

In case of release of energy to external environment Enthalpy change<94.6