Matter & Materials and Processing

Question 1

When a substance has melted, are the solid and liquid the same material?

Answer 1

Yes

Question 2

Is dissolving the same as melting?

Answer 2

No. One material dissolves in another. This may involve a chemical reaction.

Question 3

Do all solids melt on heating?

Answer 3

No, they may burn or decompose.

Question 4

What is the name of the solid which dissolves in another?

Answer 4

Solute

Question 5

What is the name of the liquid a substance dissolves in?

Answer 5

Solvent

Question 6

Give an example of a solvent.

Answer 6

Water. Solubility is an important property of water.

Question 7

Give an example of three solutes.

Answer 7

1. Sugar
2. Salt
3. Saltpeter ( potassium nitrate)

Question 8

When a melted substance re-solidifies does it always return to it’s original form or shape?

Answer 8

No.

Question 9

What does the combination of a solute and solvent give?

Answer 9

Solution

Question 10

Are all liquids soluble in water?

Answer 10

No. Oil and paraffin are not soluble in water.

Question 11

Are all solids soluble in water?

Answer 11

No, solids like sand and sulphur don’t dissolve.

Question 12

Give example of two liquids that are water-soluble.

Answer 12

Methylated spirits, alcohol.

Question 13

What do you call a solution in which the solvent can’t dissolve any more solute?

Answer 13

Saturated.

Question 14

What do you call a solution that continues to dissolve a solute?

Answer 14

Unsaturated

Question 15

What happens to a hot, saturated solution that is cooled?

Answer 15

Crystals are formed.

Question 16

What do you call the process of forming crystals?

Answer 16

Crystallisation

Question 17

Once a solution is formed, how do you separate the solute from the solvent?

Answer 17

Make sure it is saturated and then heat it. Once it cools the solute will form crystals.

Question 18

What is melting?

Answer 18

When a substance is heat and it changes from a solid to a liquid.

Question 19

Does stirring make a solute dissolve faster?

Answer 19

Yes, stirring increases the rate of solubility

Question 20

What happens if a saturated solution of copper sulphate is left to stand for a few days?

Answer 20

The solvent (water) evaporates and the solute (copper sulphate) can be recovered

Question 21

Give an example of crystallized solutes found in everyday life.

Answer 21

Stalactites and stalagmites

Question 22

How are stalactites formed in a cave?

Answer 22

1. Water mixes with lime from the limestone rock.
2. This drips from the ceiling.
3. Lime crystallizes from the solution as the water evaporates.
4. A stalactite is formed.

Question 23

Does the size of a solid affect its solubility?

Answer 23

Yes, a finer grained salt dissolves faster than a coarse grain.

Question 24

Does heating increase the rate of solubility?

Answer 24

Yes. When the solvent is heated, the particles move faster than in a cooler solvent. This allows the solute and solvent to mix quicker.