Hi I need your help again.
https://drive.google.com/open?id=0Bziu2m7eQFelZXZhZEdBd1Y2akE
For f, since deltaH = deltaH2 - deltaH3 + deltaH(H2O), am i correct
to say that residual heat from experiment 1 (hcl+naoh) causes the
temperature change for experiment 2 (mg+hcl) to be higher than
expected, making the value more exothermic. Furthermore, heat lost
to the surroundings (mgo+hcl) causes the temperature
change for experiment 3 to be lower than expected, making
the value less exothermic. I feel that my answers are contradicting
themselves as there should be residual heat from both experiment 1
and 2 causing the enthalpy change for 3 to be incorrect.
For g, i have absolutely no clue on how to approach the
question.
f) The discrepancy is due to the differing state symbol of water.
In the experiment, it's H2O(g). In the calculations, it's
H2O(l).
g) Since the enthalpy change of hydration applies equally for
both alternative intermediate steps in our enthalpy cycle
generating [Mg(H2O)n]2+(aq), they in effect cancel out (when
applying Hess' Law) and hence does not affect our enthalpy change
calculations of Mg to MgO.
