C5 Chemical Change Flashcards
What is an acid?
When dissolved in water, its solution has a pH value less than 7. Acids are proton (H+ ion) donors.
What is an alkali?
Its solution has a pH value more than 7.
What is a base?
The oxide, hydroxide, or carbonate of a metal that will react with an acid, forming a salt as one of the products. If a base dissolves in water it is called an alkali. Bases are proton (H+ ion) acceptors.
What is a displacement reaction?
A reaction in which a more reactive element takes the place of a less reactive element in one of its compounds or in solution.
What is electrolysis?
The breakdown of a substance containing ions by electricity.
What is equilibrium?
The point in a reversible reaction at which the forward and backward rates of reaction are the same. Therefore, the amounts of substances present in the reacting mixture remain constant.
What is a half equation?
An equation that describes reduction (gain of electrons) or oxidation (loss of electrons).
What is an ionic equation?
An equation that shows only those ions or atoms that change in a chemical reaction.
What is a metal ore?
A rock that contains enough of a metal or metal compound that it is worth extracting the metal.
What does neutral mean?
A solution with a pH value of 7 which is neither acidic nor alkaline. Alternatively, something that carries no overall electrical charge.
What is neutralisation?
The chemical reaction of an acid with a base in which a salt and water are formed. If the base is a carbonate or hydrogen carbonate, carbon dioxide is also produced in the reaction.
What is an ore?
Rock which contains enough metal to make it economically worthwhile to extract the metal.
What is oxidation/oxidised?
A reaction where oxygen is added to a substance or when electrons are lost from a substance.
What is pH/pH scale?
A number which shows how strongly acidic or alkaline a solution is.
What is the reactivity series?
A list of elements in order of their reactivity.
What is reduction/reduced?
A reaction in which oxygen is removed or electrons are gained.
What is a salt?
A compound formed when some or all of the hydrogen in an acid is replaced by a metal.
What are strong acids?
These acids completely ionise in aqueous solutions.
What are weak acids?
Acids that do not ionise completely in aqueous solutions.
