Starter quiz
- What does the arrow (→) in a chemical equation represent?
- Equals
- Reacts with
- Changes into ✓
- Is less than
-
- Match each description with the correct state symbol:
- Solid⇔(s) ✓
- Liquid⇔(l) ✓
- Gas⇔(g) ✓
- Aqueous solution⇔(aq) ✓
- Solubility refers to the ability of a substance to ______ in water.
- 'dissolve' ✓
- True or false? When a substance dissolves in ethanol it will form an aqueous solution.
- True
- False ✓
- Which of the following is true about solubility?
- All solids dissolve in water.
- Only gases dissolve in water.
- Some substances dissolve in water, and some do not. ✓
- All liquids are insoluble.
-
- In chemistry, what does "precipitation" refer to?
- The formation of a solid from a solution. ✓
- Rain, snow, sleet, or hail that falls to the ground.
- The process of a liquid turning into a gas.
- The solidification of molten rock.
-
Exit quiz
- What is a precipitate?
- A substance that dissolves in water.
- A gas produced in a chemical reaction.
- A liquid that evaporates quickly.
- An insoluble solid formed when two solutions react together. ✓
-
- Why are precipitation reactions used in qualitative analysis?
- To measure the quantity of a substance.
- To confirm the presence of a substance. ✓
- To increase the temperature of a solution.
- To dissolve solids in a solution.
-
- A substance that will not dissolve in a particular solvent is described as ______.
- 'insoluble' ✓
- Which term describes a chemical test that confirms the presence of a substance without measuring its quantity?
- Quantitative analysis
- Spectroscopic analysis
- Qualitative analysis ✓
- Precipitation analysis
-
- An ______ solution is formed when a substance is dissolved in water.
- 'aqueous' ✓
- A precipitate is an insoluble ______ in a solution.
- 'solid' ✓
Worksheet
Presentation
Video
Lesson Details
Key learning points
- Precipitation reactions occur when two solutions combine to form an insoluble solid.
- The appearance of a precipitate is evidence that a chemical reaction has occurred.
- Precipitation reactions are important in water treatment, to remove unwanted substances from water.
- Precipitation reactions are used in qualitative analysis, to identify the presence of certain substances in a solution.
Common misconception
Pupils can struggle to understand that a solid is not always a large piece of a substance.
Show visually the difference between a transparent coloured solution e.g. copper sulfate solution and a coloured precipitate solution. Practice describing the difference between a white precipitate and a transparent colourless solution.
Keywords
Precipitation - The process where a precipitate is formed.
Precipitate - An insoluble solid formed when two solutions react together.
Aqueous solution (aq) - Formed when a substance is dissolved in water.
Insoluble - A way of describing a substance that will not dissolve in a particular solvent.
Chemical qualitative analysis - A chemical test that confirms the presence of a substance, it does not tell you how much of the substance is present.