5.4 Chemical Change Flashcards
Acid
Acids produce hydrogen ions (H + ) in aqueous solutions.
They have a pH range of 0-6
Alkali
Alkalis produce hydroxide ions (OH - ) in aqueous solutions.
They have a pH range of 8-14
Crystallisation
A separation technique used to produce solid crystals from a solution by evaporating the solvent
Displacement
A chemical reaction in which a more reactive element displaces a less reactive element from its compound
Electrolysis
The splitting up of an ionic compound using electricity.
The electric current is passed through a substance causing chemical reactions at the electrodes and the decomposition of the materials
Electrolyte
A solution containing free ions from the molten or dissolved ionic substance.
The ions are free to move to carry charge
Extraction
Extraction techniques are used to separate a desired substance when it is mixed with others
Filtration
A separation technique used to separate solids from liquids
Negative electrode (cathode)
The electrode where hydrogen is produced if the metal in the
electrolyte is more reactive than hydrogen
Neutralisation
The reaction when an acid and a base react to form water and a salt
Oxidation
A reaction involving the gain of oxygen
pH scale
The pH scale, from 0 to 14, is a measure of the acidity or alkalinity of a solution, and can be measured using universal indicator or a pH probe
Positive electrode (anode)
The electrode where oxygen is produced unless the solution
contains halide ions then the halogen is produced
Reduction
A reaction involving the loss of oxygen
Reduction with carbon
Metals less reactive than carbon can be extracted from their oxides by reduction with carbon
The reactivity series
Metals are arranged in order of their reactivity in a reactivity series.
This can be used to predict products from reactions
Universal indicator
A mixture of dyes that changes colour gradually over a range of pH and is used in testing for acids and alkalis
