PAG 1

Preparation of a salt from an insoluble metal carbonate or oxide

This PAG is in PAPER 1

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Background Information and Keywords

Keywords

Solute - A chemical dissolved in a solvent

Solvent - A liquid which the solute is dissolved in (e.g. water)

Solution - When a solute has been dissolved in a solvent

Soluble - When a chemical can be dissolved in a solvent

Insoluble - When a chemical cannot be dissolved in a solvent

Evaporation - When a substance turns from a liquid to a gas

Crystallisation - A process by which a solution is heated, causing the water/solvent to evaporate, leaving behind the solute

Filtration - A process by which an insoluble solid is removed from a liquid by passing the liquid through filter paper

"In excess" - When there is more of a chemical than is needed for a chemical reaction. Some of the chemical is left behind at the end

Background Information

Salts are ionic substances which can be soluble or insoluble
Salts are generally made when acids react with other chemicals.

e.g.

Hydrochloric acid + Sodium --> Sodium chloride + Hydrogen

Acids can react with metals, metal carbonates, metal oxides and metal hydroxides (i.e. alkalis) to produce salts.
In this practical we generally react together sulfuric acid with either copper oxide or copper hydroxide to make copper sulfate salt (the blue crystals)
However, once the copper sulfate has been made, it needs to be purified
To do this we use filtration and crystallisation

"How To Do It" Video

Watch this video to remind yourself how this practical is carried out.

What are the key steps to this practical?
Why is each step done?
What/why are the safety precautions taken?

Diagram

Key Steps

Heat sulfuric acid over a bunsen burner (but don't boil it!)
Add copper oxide a little at a time and stir
Continue to add copper oxide until some remains after stirring
Filter the mixture into a conical flask
Pour the solution into a crystallising dish
Heat the solution in the dish until crystals form

Key Questions from this Practical

Why is the sulfuric acid heated before the copper oxide is added?
Why is the mixture filtered before being crystallised?
Why is the mixture crystallised?
What is the word and symbol equation for this reaction?
What are some safety precautions which need to be taken during this practical?

Question Practice and Exam Questions

Required Practicals Mastery Booklet - PAG 1 - Making Soluble Salts.pdf

PAG 1: Mastery Question Booklet

This Mastery Booklet is filled with questions and exam questions to help you master this core practical. All answers and mark schemes are attached at the end.

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