Paper 1 - Topic 4, Chemical Changes Flashcards
What do acids produce in aqueous solutions
Hydrogen ions (H+)
What’s the pH range for an acid
0-6
What do alkalis produce in aqueous solutions
Hydroxide ions (OH-)
What is the pH range for alkalis
8-14
What is crystallisation
A separation technique used to produce solid crystals from a solution by evaporating the solvent
What is displacement
A chemical reaction in which more reactive element displaces a less reactive element from its compound
What is 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
What is an electrolyte
A solution containing free ions from the molten or dissolved ionic substance, the ions are free to move to carry charge
What are extraction techniques used for
Extraction techniques are used to separate a desired substance when it is mixed with others
What is filtration
A separation technique used to separate solids from liquids
What happens at the negative electrode (cathode)
Hydrogen is produced if the metal in the electrolyte is more reactive than hydrogen and positively charged ions gain electrons, this is a reduction reaction
What is neutralisation
The reaction when an acid and a base react to form water and a salt
What is oxidation
A reaction involving gaining oxygen, oxidation is the loss of electrons
What is the pH scale used for
To measure the acidity or alkalinity of a solution and can be measure using a universal indicator or a pH probe
What happens at the positive electrode (anode)
Oxygen is produced at the anode unless the solution contains halide ions then the halogen is produced, it is where negatively charged ions lose electrons, this is an oxidation reaction
What is a redox reaction
A reaction in which both oxidation and reduction occurs simultaneously
What is reduction
A reaction invoking the loss of oxygen, reduction is the gain of electrons
What is reduction with carbon
Where metals less reactive than carbon can be extracted from their oxides by reduction with carbon
What is a strong acid
A strong acid is completely ionised in aqueous solution, examples are hydrochloric acid and sulphuric acids
What is the reactivity series
Metals arranged in order of their reactivity, this can be used to predict products from reactions
What is titration
A technique used where a solution of known concentration is used to determine the concentration of an unknown solution
What is a Universal indicator
A mixture of dyes that changes colour gradually over a range of pH and is used for testing for acids and alkalis
What is a weak acid
A weak acid is only partially ionised in aqueous solution, examples are acid ethanoic and carbonic acids
How are unreactive metals found in Earth
In their natural state
