Chemical changes Flashcards
What is a balanced equation?
In a balanced symbol equation, chemical formulae represent the reactants and products. The relative amounts of reactants and products are shown.
Define a chemical reaction.
A change where atoms are rearranged to create a new substance.
Define combustion.
A chemical reaction in which a substance reacts quickly with oxygen and gives out light and heat.
What is conservation of mass?
In a chemical reaction, the total mass of reactants is equal to the total mass of products. Mass in conserved in chemical reactions and physical changes.
What is decomposition?
A chemical reaction in which a compound breaks down to form simpler compounds and/ or elements.
Define displacement.
When a metal takes place of a less reactive metal in the compound.
What does an endothermic reaction do?
Takes energy from the surroundings.
What does an exothermic reaction do?
Releases energy to the surroundings.
Define fuel.
A material that is burnt for energy, usually heat.
What is a hazard?
A possible source of DANGER…
What is neutralisation?
When an acid and base (alkalis) react together changing the pH of a mixture.
What is oxidation?
A chemical reaction in which substances react with oxygen to form oxides.
Define a physical change.
A change that is reversible and no new substances are made e.g. evaporating water.
What is a product?
A substance that is made in a chemical reaction.
What is a reactant?
A starting substance in a chemical reaction.
What is thermal decomposition?
When a compound is broken down using heat alone.
What is a word equation?
A way of representing a chemical reaction simply.
Copper + sulphur + oxygen > ?
Copper sulphate
What liquid do you use to tell if a substance is thermally decomposing?
Limewater.
What is the chemical symbol for oxygen?
O
What is the chemical symbol for nitrogen?
N
What is the chemical symbol for zinc?
Zn
What is the chemical symbol for hydrogen?
H
What is the chemical symbol for potassium?
K
