the heat energy change measured under constant pressure.
in a chemical reaction, what does the heat energy change occur between?
the system and the surroundings.
what does the system contain?
the reactants and products.
what is the surroundings?
the container in which the reaction takes place, the air around the reaction or the solution containing the reaction.
endothermic reaction.
the system takes in heat energy from the surroundings so the temperature of the surroundings decreases. The reactants have lower energy than the products. The enthalpy of the system increases.
exothermic reaction.
the system gives out heat energy to the surroundings so the temperature of the surroundings decreases. The reactants have higher energy than the products. The enthalpy of the system decreases.
