C7 - Energy Changes Flashcards
What is the law of the conservation of energy?
Energy is conserved, meaning the amount of energy in the universe is the same at the start of a reaction and at the end of a reaction.
Is breaking bonds exothermic or endothermic?
Endothermic
Is making bonds exothermic or endothermic?
Exothermic
What does it mean if a reaction is endothermic (in terms of energy)?
Energy from breaking bonds is bigger, more energy has been supplied/ taken in than the amount of energy released
What does it mean if a reaction is exothermic (in terms of energy)
Energy from making bonds is bigger, more energy has been released than energy has been taken in
What happens to the temperature of the surroundings if a reaction is exothermic?
The temperature of the surroundings has increased due to the reaction giving out energy.
What happens to the temperature of the surroundings if a reaction is endothermic?
The temperature of the surroundings has decreased due to the reaction taking in energy.
What are some examples of exothermic reactions?
•self-heating hand warmers
•self-heating coffee cups
What are some examples of endothermic reactions?
•thermal decomposition reactions
•reactions between citric acid and sodium bicarbonate
•instant ice packs
What is a reaction profile diagram?
A diagram that shows the energy of the chemical bonds in the reactants and of the products and how much energy is required to start the reaction (activation energy).
What is activation energy?
The amount of energy that is required to start a reaction
What is a cell made of?
Two different metals and an electrolyte
