Solutions and formation of crystals

Question 1

Definition of a solvent

Answer 1

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

Question 2

What is an excellent solvent?

Answer 2

Water is an excellent solvent as a very large number of substances dissolve in it.

Question 3

What is a solute?

Answer 3

The substance that dissolves in the water/solvent is the solute

Question 4

What is a solution?

Answer 4

The mixture of solute and solvent is called the solution. e.g sugar dissolves in water to form a solution of sugar in water.

Question 5

Definition of soluble

Answer 5

A substance that dissolves in water is said to be soluble e.g. sugar is soluble in water

Question 6

Definition of insoluble

Answer 6

A substance that does not dissolve in water is said to be insoluble in water e.g. sand is insoluble in water.

Question 7

What is copper sulfate and what is it used for?

Answer 7

Copper sulfate is a blue substance found in labs that is used to kill fungi and for preserving timber.

Question 8

What is one of the properties of a solution?

Answer 8

One of the properties of solutions is that they are always clear (light passes through them)

Question 9

Definition of a suspension and give an example of this.

Answer 9

A suspension is a mixture in which small solid or liquid particles are suspended in a liquid (or gas). Muddy water is an example of a suspension of mud particles in water. Milk is also an example of a suspension with fat particles suspended in the solution.

Question 10

Definition of a dilute solution

Answer 10

A dilute solution is one in which there is a small amount of solute on a large amount of solvent.

Question 11

Definition of a concentrated solution

Answer 11

A concentrated solution is one in which there is a large amount of solute in a small amount of solvent.

Question 12

Describe the bottle of cordial (mi wadi) and a glass of water and cordial

Answer 12

The bottle contains a concentrated solution and the glass contains a dilute solution of orange squash.

Question 13

Definition of a crystal

Answer 13

A crystal is a solid with a regular shape and smooth faces. The particles inside the crystal are arranged in a regular pattern.

Question 14

What do crystals have?

Answer 14

Crystals have a definite shape and are usually shiny.

Question 15

What do non-crystalline solids have?

Answer 15

Non-crystalline solids (such as flour) have no definite shape and are usually dull in appearance.

Question 16

Give an example of an experiment where you grow crystals then list the conclusions of the experiment

Answer 16

To grow crystals with copper sulfate.
Conclusions:
More copper sulfate dissolves at a higher temperature.
Crystals are formed when a hot, concentrated solution Is cooled.
The crystals formed by slow cooling are bigger than the crystals formed by rapid cooling.

Question 17

Definition of a saturated solution and give an example of such.

Answer 17

A saturated solution is one that contains as much dissolved solute as possible at a given temperature.
An example of this is in the experiment where crystals are grown from copper sulfate. The amount of copper sulfate that can be dissolved at a certain temperature.

Question 18

Definition of unsaturated

Answer 18

A solution that is not saturated is said to be unsaturated. In other words, an unsaturated solution has not dissolved the max amount of solute at a given temperature

Question 19

Solubility definition and example

Answer 19

The solubility of a substance is the mass of it (in grams) that will dissolve in 100 grams of solvent at a fixed temperature. e.g. the solubility of copper sulfate is 40g/100g water at 60 degrees celsius.

Question 20

What is proved when copper sulfate is added to water placed on a hot plate that is gradually getting hotter?

Answer 20

The solubility of copper sulfate increases as the temperature is increased.

Question 21

Solubility curve definition

Answer 21

A Solubility curve is a graph showing how the solubility of a substance varies with temperature.

Question 22

What does a Solubility curve help to explain?

Answer 22

Solubility curves help to explain why crystals are formed.

Question 23

What is crystallisation?

Answer 23

Crystallisation is the formation of crystals when a hot saturated solution is cooled.

Question 24

Does each substance have its own solubility curve?

Answer 24

Yes, each substance has its own solubility curve.

Question 25

Can copper sulfate in the solid-state conduct electricity?

Answer 25

Substances such as copper sulfate do not conduct electricity in the solid state because the charged particles in the crystals are locked in fixed positions and cannot carry the electric current through the crystal.

Question 26

Can copper sulfate solution conduct electricity?

Answer 26

When the crystals are dissolved in water, these charged particles are now free to move and can carry an electric current. We say that copper sulfate solution conducts electricity.

Question 27

Give an example of a solution that conducts and doesn’t conduct electricity.

Answer 27

Copper sulfate solution conducts electricity while a sugar and water solution doesn’t conduct electricity. Sugar solution is covalent while copper sulfate solution is ionic.

Question 28

What are suspensions usually?

Answer 28

Suspensions are usually cloudy (doesnt let light travel through it)