Dissolving booklet
Dissolving booklet
- Unit 1: Living things
- Unit 2: Sound
- Unit 3: Materials in my world
- Unit 4: The Earth
- Unit 5: Humans
- Unit 6: Forces
This Topic is About...
- I will find out that in a mixture of a solid and a liquid, sometimes the solid dissolves.
- I will ask a scientific question and plan a scientific enquiry to find the answer.
- I will record observations in tables and diagrams.
- I will learn how we can stay safe in an investigation.
You’re going to be a science explorer!
Key Words
- dissolve
- insoluble
- soluble
- transparent
Tap to Learn the Meanings!
- dissolve: When a solid mixes completely into a liquid so it seems to disappear.
- insoluble: A substance that does not dissolve in a liquid.
- soluble: A substance that can dissolve in a liquid.
- transparent: Something you can see through clearly, like clean glass or water.
Great work! You’re learning key words about solutions and materials.
Solids that dissolve in liquids
Some solids dissolve when they are mixed with a liquid. This means the solid breaks into pieces that are too small to see. When the solid has dissolved we cannot see it but it is still there.
See-through (transparent) liquids
Many liquids are see through. We say they are transparent. When a solid dissolves in a transparent liquid the liquid stays transparent but might change colour.
Soluble and insoluble solids
We describe solids that dissolve in a liquid as soluble. Sugar dissolves in water, so sugar is soluble in water. We describe solids that do not dissolve in a liquid as insoluble.
Sand as an insoluble solid
Sand does not dissolve in water, so sand is insoluble in water.
Mixtures with insoluble solids
An insoluble solid in a liquid is a mixture and can be easily separated.
Mixtures with soluble solids
A soluble solid in a liquid is still a mixture but is more difficult to separate.
FUN QUESTIONS
1. What word describes a solid that will dissolve in a liquid?
Show answer
2. What word describes a solid that will not dissolve in a liquid?
Show answer
3. Sugar dissolves in water. Name any other solids that dissolve in water.
Show answer
Let’s Investigate!
Topic: How much salt will dissolve in water?
You will need: three drinking glasses, a spoon, some salt, water
Investigation steps:
- Look at the picture to see how to set up the investigation.
- Add half a spoon of salt into each glass of water.
- Stir each glass.
- Observe to see whether the salt dissolves.
- Add another half spoon of salt to each glass, stir again, and observe.
- Continue adding salt until it no longer dissolves — this is when the water becomes saturated.
- Write your results in a table like the one shown.
- Discuss your predictions before you start.
Questions to think about:
- In which glass did the least salt dissolve?
- In which glass did the most salt dissolve?
- How does the amount of water affect the amount of salt that will dissolve?
Tap to See Example Answers
- Least salt dissolved: The glass with the smallest amount of water.
- Most salt dissolved: The glass with the largest amount of water.
- Why this happens: More water means more space between water particles, allowing more salt to dissolve before the water becomes saturated.
- Pattern: The greater the volume of water, the greater the amount of salt it can dissolve.
- Type of enquiry: This was a fair test, because only one variable changed: the amount of water.
Great job! You explored how dissolving works and discovered how water volume affects solubility.
Let’s Investigate!
Topic: Asking questions about dissolving
You will need: a spoon, some cups, water, vinegar, cooking oil (or other liquids), salt, sugar, sand, flour, jelly crystals
Investigation steps:
- Arun has a scientific question: Which liquids will salt dissolve in?
- Think about the five types of scientific enquiry. Which one will help you answer this question? (research, fair testing, observing over time, identifying & classifying, pattern seeking)
- In your group, look at the materials and ask your own question, such as: Which liquids will _________ dissolve in?
- Plan your own fair test. Draw a diagram to show what you will do.
- Remember: in a fair test, you change one thing (the type of liquid) and keep everything else the same.
- Observe whether the solid dissolves in each liquid.
- Label your diagram to show the variables you will keep the same.
Safety reminder:
Do NOT taste any of the materials in this investigation.
More to think about:
- Why is it unsafe to taste the materials?
- Write sentences to record your results using the words soluble and insoluble.
- Example:
- Salt is soluble in water and vinegar.
- Salt is insoluble in cooking oil.
Tap to See Example Answers
- Type of enquiry: A fair test because only the liquid is changed while all other variables stay the same.
- Keeping it fair: Same amount of solid, same stirring, same cup size, same water temperature, same observation time.
- Why you shouldn’t taste materials: Some substances may be harmful, contaminated, or unsafe to swallow.
- Example results:
- Sugar is soluble in water.
- Flour is insoluble in water (it forms a cloudy mixture).
- Sand is insoluble in all tested liquids.
- Jelly crystals are soluble in warm water but not in oil.
- Conclusion: Different solids dissolve in different liquids depending on their properties.
Excellent scientific thinking! You planned a fair test and used the ideas of solubility and variables correctly.
How am I doing?
Look at another group’s diagram. Have they made it a fair test? Tell them if there is anything else they need to keep the same.