Chemical Changes Higher DRIP

How ionising is a strong acid in an aqueous solution?

A strong acid is completely ionised in an aqueous solution.

Give some examples of strong acids

Hydrochloric, nitric and sulfuric acids.

How ionising is a weak acid in an aqueous solution?

A weak acid is only partially ionised in an aqueous solution.

Give some examples of weak acids

Ethanoic, citric and carbonic acids.

What is the relationship between concentration of acid and pH?

For a given concentration of aqueous solutions, the stronger an acid, the lower the pH.

As pH decrease by a single unit, what happens to the hydrogen ion concentration in the solution?

As pH decreases by one unit, the hydrogen ion concentration of the solution increases by a factor of 10.

What happens to the ions in an ionic compound when melted or dissolved?

The ions are free to move about within the liquid or solution.

What is special about a molten or liquid ionic compound?

These liquids and solutions are able to conduct electricity,.

What is the name of a molten or ionic liquid?

Electrolytes.

What happens when you pass electric current through electrolytes?

Causes the ions to move to the electrodes.

What direction do positively charged ions move?

Positive electrons move to the negative electrode (the cathode)

What direction do negatively charged ions move?

To the positive electrode (anode)

What happens to an ion once they arrive at the electrode?

Ions are discharged at the electrodes producing elements.

What is the name of the process where electric current is passed through an electrolyte?

Electrolysis.

What happens when a simple ionic compound is electrolysed such as lead bromide in the molten state?

The metal (lead) is produced at the cathode and the non-metak (bromine) is produced at the anode.

Why do we use electrolysis during metal extraction?

Metals can be extracted from molten compounds using electrolysis.

Why is electrolysis only used for only some metals?

Electrolysis is used if the metal is too reactive to be extracted by reduction with carbon or if the metal reacts with carbon.

What is the disadvantage in using electrolysis for metal extraction?

Large amounts of energy are used in the extraction process to melt the compounds and to produce the electrical current.

How is aluminium manufactured?

By the electrolysis of a molten mixture of aluminium oxide and cryolite using carbon as the positive electrode (anode)

What affects how ions are discharged during electrolysis?

Relative activity of the elements involved.

What is produced at the negative electrode if the metal is more reactive than hydrogen?

Hydrogen is produced if the metal is more reactive than hydrogen.

What forms at the positive electrode unless the solution contains halide ions?

Oxygen is produced unless the solution contains halide ions when the halogen is produced.

What type of reaction happens at the cathode when positive ions gain electrons?

Positively charged ions gain electrons and so the reactions are reductions.

What type of reaction happens at the anode when a negative ion loses electrons?

Negatively charged ions lose electrons and so the reactions are oxidations.