Chapter 1-States of Matter, Diffusion and Solubility

Question 1

What is the arrangement of particles in a solid?

Answer 1

The arrangement of the particles in a solid is regular and they are closely packed.

Question 2

What is the arrangement of particles in a liquid?

Answer 2

The arrangement of the particles in a liquid is random, with the particles still mainly touching but with some small gaps.

Question 3

What is the arrangement of the particles in a gas?

Answer 3

The arrangement of the particles in a gas is random and they are much further apart.

Question 4

What is the movement of the particles in a solid like?

Answer 4

The particles in a solid vibrate in fixed positions; they can’t move around.

Question 5

What is the movement of the particles in a liquid like?

Answer 5

The particles in a liquid move around each other.

Question 6

What is the movement of the particles in a gas like?

Answer 6

The particles in a gas move randomly at high speed in all directions.

Question 7

How much kinetic energy does a solid have?

Answer 7

Little kinetic energy.

Question 8

How much kinetic energy does a liquid have?

Answer 8

More kinetic energy than a solid but less kinetic energy than a gas.

Question 9

How much kinetic energy does a gas have?

Answer 9

The most kinetic energy between solids, liquids and gases.

Question 10

Describe the forces of attraction between the particles in a solid.

Answer 10

The forces of attraction between the particles in a solid are strong; this keeps the particles together.

Question 11

Describe the forces of attraction between the particles in a liquid.

Answer 11

The forces of attraction between the particles in a liquid are weaker than those of a solid and so are less effective, meaning that the particles can move around.

Question 12

Describe the forces of attraction between the particles in a gas.

Answer 12

There are almost no forces of attraction between the particles in a gas, meaning the particles can move around quickly and randomly in all directions.

Question 13

What are the names of the interconversions between a solid and liquid and how are they achieved?

Answer 13

The process of changing a solid into a liquid is called melting and is achieved by heating.
The process of changing a liquid into a solid is called freezing and is achieved by cooling.

Question 14

What are the names of the interconversions between a liquid and gas and how are they achieved?

Answer 14

The process of changing a liquid into a gas is called boiling and is achieved by heating. This conversion can also be done using a process called evaporation and is also achieved by heating.
The process of changing a gas into a liquid is called condensing and is achieved by cooling.

Question 15

What are the names of the interconversions between a solid and a gas and how are they achieved?

Answer 15

The process of changing a solid into a gas is called sublimation and is achieved by heating.
The process of changing a gas into a solid is called deposition and is achieved by cooling.

Question 16

What is the difference between evaporation and boiling?

Answer 16

Evaporation occurs slowly at any temperature whereas boiling occurs quickly at a fixed temperature-the boiling point of the liquid.

Question 17

What is the temperature of the melting point of a substance the same as?

Answer 17

The freezing point of a substance.

Question 18

What happens when a solid is heated?

Answer 18

When a solid is heated, the particles gain energy and vibrate faster. When they vibrate fast enough, the forces of attraction between the particles weaken and the particles can move around. The solid melts to form a liquid.

Question 19

What happens when a liquid is heated?

Answer 19

When a liquid is heated, the particles gain energy until they move around fast enough to break all the forces of attraction between the particles and the liquid boils. Bubbles of gaseous particles form, rise to the surface and escape as a gas.

Question 20

What happens when a gas is heated?

Answer 20

When a gas is heated, the gas particles simply move faster.

Question 21

Why does the temperature not rise but stay the same when a substance melts or boils?

Answer 21

Because energy is used to overcome the forces of attraction between the particles.

Question 22

How do you work out if a substance is a solid at room temperature?

Answer 22

If a substance is a solid at room temperature, its melting and boiling points will be above the room temperature.

Question 23

How do you work out if a substance is a liquid at room temperature?

Answer 23

If a substance is a liquid at room temperature, the room temperature will be between its melting and boiling point.

Question 24

How do you work out if a substance is a gas at room temperature?

Answer 24

If a substance is a gas at room temperature, the room temperature will be above its melting and boiling points.

Question 25

What is diffusion?

Answer 25

Diffusion is the spreading out of particles from where they are at a high concentration (there are lots of them in a certain volume) to where they are at a low concentration (there are fewer of them in a certain volume).

Question 26

What is the solute?

Answer 26

The solute is the substance (e.g. solid) which dissolves.

Question 27

What is the solvent?

Answer 27

The solvent is the liquid (often water) that the solute dissolves in.

Question 28

What is the solution?

Answer 28

The solution is the mixture made by dissolving a solute in a solvent.

Question 29

What is a saturated solution?

Answer 29

A saturated solution is a solution which contains as much dissolved solute as possible at a particular temperature (with some undissolved solute present).

Question 30

What is solubility?

Answer 30

Solubility is the maximum mass of solute that can dissolve in 100g of solvent at a particular temperature. It is measured in g per 100g of solvent (g/100g or g/100cm3).

Question 31

What happens to solubility as the temperature increases? Why?

Answer 31

The solubility (mass of solid dissolved in 100g of solvent) increases as the temperature increases. This is because as a liquid is heated, the particles of water move further apart, allowing more solid to fit between them. The energy of water molecules also increases because the molecules move about more and this helps to break down the solute particles.

Question 32

Describe a practical to investigate the solubility of a solid in water at a specific temperature (e.g.40 degrees Celsius).

Answer 32

1. Measure out 100g (100cm3) of water.
2. Heat water to above 40 degrees Celsius.
3. Add solid until no more will dissolve.
4. Cool solution to exactly 40 degrees Celsius.
5. Quickly filter (or pour off solution-no solid) into a weighed evaporating basin (A).
6. Reweigh the evaporating basin (B).
7. Evaporate off the water and and reweigh (C).
8. Determine the mass of solid dissolved (C-A) and the mass of water evaporated (B-C).
9. Calculate the solubility of the solid at 40 degrees Celsius: mass of solid/mass of water x 100.

Question 33

What is a safety point for the solubility practical?

Answer 33

Wear goggles-the solution may spit when being heated.