On Monday afternoon, Year 6 planned and carried out a fair investigation. Here is a write up of what we did
We are investigating the speed that sugar dissolves in water.
Materials we will need: Kettle, beakers, thermometer, water of different temperatures, stopwatch, ice, sugar
Variables we will change: Temperature of the water
Variables we will keep the same (to make it a fair test): Same person measuring and stirring the sugar, same equipment and volume of water
Variables we will measure:The time it takes for the sugar to dissolve
- Collect the beakers/ water and measure the starting temperature
- Beaker 1 – 200ml hot (start temperature)
- Beaker 2 – 150ml hot/ 50ml cold (start temperature)
- Beaker 3 – 100ml hot/ 100 ml cold (start temperature)
- Beaker 4 – 50 ml hot/ 150ml cold (start temperature)
- Beaker 5 – 200 ml cold (start temperature~)
2. Pour a level teaspoon of sugar into the beaker and start the timer
3. Stir the water until the sugar has completely dissolved
4. Record timings. Repeat the test.
The reason the hot water dissolves more is because it has faster moving molecules which are spread further apart than the molecules in cold water. With bigger gaps between the molecules in the hot water, more sugar molecules can fit in between them.
Questions for you to think about…..
What do we mean by dissolving? Does it completely disappear? How do you know?
Can you think of some examples where dissolving takes place?
What other factors may affect the rate that sugar dissolves?
What do we mean by a fair test? How can we ensure this happens?
Why do we need to repeat a test and collect more than one set of results?