How much sugar dissolves?
Stir sugar or salt into water at different temperatures until no more dissolves. See how hot water dissolves far more sugar, while salt hardly changes, and why syrup for sweets is made hot.
Core concept
Solubility is the most of a substance that dissolves in 100 g of water at a given temperature; sugar's solubility rises steeply with temperature, but salt's hardly changes
Topic: Chemistry in the kitchen
When sugar dissolve: To mix into a liquid so completely that you can no longer see the pieces. All key words in water, it spreads out between the water particle: A tiny piece that matter is made of, far too small to see. All key words and seems to disappear. But water can only hold so much. When no more will dissolve, the solution: A mixture where one substance has dissolved completely in a liquid, like salt water. All key words is saturated, and extra sugar sits at the bottom. The amount that dissolves in 100 g of water is called the solubility. It depends on the temperature: How hot or cold something is, measured in degrees Celsius (°C). All key words: hot water particles move faster and make room for much more sugar. At 20 °C, 100 g of water dissolves about 204 g of sugar, twice its own mass: How much matter something has, measured in grams or kilograms. It is the same everywhere. All key words; at 100 °C it dissolves about 487 g. Salt is different: about 36 g dissolves at 20 °C and only about 39 g at 100 °C. More water also dissolves more: twice the water, twice the sugar.
What you will learn
- Explain what a saturated solution and solubility are.
- Describe how temperature changes the solubility of sugar and of salt.
- Work out how much dissolves in a given amount of water.
Before you start
- Know the words solute, solvent and solution.
Materials
- Sugar, salt, water and a teaspoon
- Two clear glasses
Equipment
- A kitchen scale
- A thermometer
Procedure
- Record sugar in 100 g of water at 20 °C.
- Heat the water to 80 °C and record.
- Change to salt and record at 80 °C, then at 20 °C.
How this simulation is simplified
- Grams that dissolve in 100 g of water. Sugar (sucrose): 179, 204, 238, 287, 362 and 487 g at 0, 20, 40, 60, 80 and 100 °C. Salt: 35.7, 36, 36.6, 37.3, 38.4 and 39.2 g.
- 1 mL of water has a mass of 1 g.