1) The answer is: a) absorbed 20 kJ.
potential energy = bond energy of the product - bond energy of the reactants.
ΔE = 60 kJ - 40 kJ.
ΔE = 20 kJ; potential energy.
2) The answer is: endothermic.
This is endothermic reaction (ΔE > 0, chemical reaction that absorbs more energy than it releases).
In endothermic reactions heat is reactant.
3) The answer is: decrease.
In a calorimeter with endothermic reaction, the heat required by the reaction is removed from the water and the temperature of the water decreases.
