CM8001

a) A charcoal briquette burns: exothermic because combustion has occurred resulting in heat radiating out

b) Water evaporates from your skin: endothermic because when water evaporates it changes from liquid to gaseous state and in the process energy is absorbed

c) Ice melts: endothermic because energy is absorbed when ice turns from solid to liquid state

Bond strength for the reactants has to be higher than the bond strength of products.
Bond energy (products) – bond energy (reactants) <0 for exothermic reactions
Therefore more energy is required to break the bonds for the reactants.

Heat exist in the form of energy while temperature is a measurement for it.
eg. Putting hot metal into cold water illustrates energy transfer where the hot metal will cool down while the water will heat up

a) The premium gasoline has octane rating of 98 where 98% is isooctane and 2% is heptane.

b) We cannot tell if the fuel contains oxygenates as the octane rating is only a ratio of hydrocarbon