Solutions

Question 1

What is a solvent?

Answer 1

A solvent is a substance that dissolves other materials to form a solution

Question 2

What is a solution?

Answer 2

A mixture of a solute and solvent

Question 3

What is a suspension?

Answer 3

When a solid added to water becomes scattered throughout the liquid and looks cloudy

Question 4

What is a dilute solution?

Answer 4

A solution with a small amount of solute and a large amount of solvent

Question 5

What is a concentrated solution?

Answer 5

A large amount of solute and a small amount of solvent

Question 6

How do you grow crystals of copper sulfate?

Answer 6

1. Grind up a sample of copper sulfate using a pestle and mortar
2. Add the substance to 100 cm3 of water until the solute no longer dissolves but settles at the bottom of the beaker. Note the water temperature
3. Heat the water to 60©
4. Pour half the solution into a warm evaporating basin to cool
5. Crystals are formed

Question 7

What is a saturated solution?

Answer 7

A saturated solution is one that contains as much dissolved solute as possible at a given temperature

Question 8

How is solubility measured?

Answer 8

The solubility of a substance is its mass (in grams) that will dissolve in 100 grams of solvent at a fixed temperature

Question 9

How do you investigate the effect of temperature on solubility?

Answer 9

1. Grind up a substance (copper sulfate) with a pestle and mortar
2. Weigh out 100g of copper sulfate
3. Place 100 cm3 of water in a beaker and heat the water to about 30©.
4. Measure the exact temperature with a thermometer
5. Add some copper sulfate and stir after each addition until no more will dissolve
6. Weigh the amount of copper sulfate not added and by subtraction calculate the amount of copper sulfate that has dissolved
7. Repeat at different temperatures to form a solubility curve

Question 10

What is a solubility curve?

Answer 10

A graph showing how the solubility of a substance varies with temperature

Question 11

What is crystallisation?

Answer 11

The formation of the crystals when a hot saturated solution is cooled or when the solvent is allowed to evaporate from the solution