From a molecular viewpoint, where does the energy emitted in an exothermic chemical reaction come from?
We’re being asked to explain where the energy emitted in an exothermic reaction comes from.
• Exothermic reactions
▪ lose energy, releases heat, temperature of the surroundings increases
▪ involves bond formation (for phase change: gas → liquid → solid)
▪ ΔH is negative
• Endothermic reactions
▪ gain/requires energy, absorbs heat, temperature of the surroundings decreases
▪ involves breaking bonds (for phase change: solid → liquid → gas)
▪ ΔH is positive