Energy changes

Cards (13)

What are exothermic reactions?
Reactions that transfer energy to their surroundings
What type of energy is transferred in an exothermic reaction?
Heat energy
What would you use to detect an exothermic reaction?
A thermometer
What are some examples of an exothermic reaction?
Combustion (burning), neutralisation between acid and alkalis and the reaction between water and calcium oxide
What are endothermic reactions? 
Reactions that take in energy from their surroundings
What are some examples of endothermic reactions?
Electrolysis, reaction between ethanoic acid and sodium carbonate and thermal decomposition of calcium carbonate in the blast furnace
What happens during a chemical reaction?
Bonds in the reactants are broken, and new bonds are formed in the products
How are bonds between molecules broken?
Energy is absorbed so it is an endothermic process
What happens when new bonds are formed?
Energy is released so it is an exothermic process
How is change in energy calculated? 
BB (Bonds Broken) - BF (Bonds Formed)
In exothermic reactions, the reactants are higher than the products
In endothermic reactions, the reactants are lower than the products
What is activation energy? 
The minimum amount of energy required for a reaction to take place