4.5.1 Exothermic and endothermic reactions Flashcards
What is energy conservation in chemical reactions?
Energy is conserved in chemical reactions; the total energy remains the same before and after the reaction.
What is an exothermic reaction?
An exothermic reaction transfers energy to the surroundings, increasing their temperature.
Examples include combustion, oxidation reactions, and neutralisation.
What are everyday uses of exothermic reactions?
Everyday uses include self-heating cans and hand warmers.
What is an endothermic reaction?
An endothermic reaction takes in energy from the surroundings, decreasing their temperature.
Examples include thermal decompositions and the reaction of citric acid and sodium hydrogencarbonate.
What are some applications of endothermic reactions?
Some sports injury packs are based on endothermic reactions.
How can students distinguish between exothermic and endothermic reactions?
Students can distinguish them based on the temperature change of the surroundings.
What is activation energy?
Activation energy is the minimum energy required for reacting particles to collide and react.
What do reaction profiles show?
Reaction profiles show the relative energies of reactants and products, activation energy, and overall energy change of a reaction.
What should students be able to do with reaction profiles?
Students should be able to draw reaction profiles for exothermic and endothermic reactions and identify them.
What happens during a chemical reaction regarding energy?
Energy must be supplied to break bonds in reactants, and energy is released when bonds in products are formed.
How is overall energy change calculated in reactions?
Overall energy change is the difference between energy needed to break bonds in reactants and energy released when bonds in products are formed.
In an exothermic reaction, what is true about bond energies?
In an exothermic reaction, the energy released from forming new bonds is greater than the energy needed to break existing bonds.
In an endothermic reaction, what is true about bond energies?
In an endothermic reaction, the energy needed to break existing bonds is greater than the energy released from forming new bonds.
