Definitions Chemistry

• A compound is formed when two or more elements chemically combine.
• A catalyst is a substance that increases the rate of reaction without being used up in the process.
• In a closed system, no reactants are added and no products are removed.
• Some chemical reactions are reversible, they can go forwards or backwards; the products make the reactants.
• The minimum amount of energy required to cause a reaction is called the activation energy.
• An exothermic reaction releases heat
• An endothermic reaction absorbs heat
• A limiting reagent is the one which runs out first during a reaction.
• When bonds are formed, energy is given out so its an exothermic reaction.
• To break bonds requires energy therefore it’s an endothermic reaction.
• Fuels are substances that can be burned to release energy.