topic 2 - energy changes

Question 1

properties of solids

Answer 1

fixed shape and volume
cannot be compressed

have a regular arrangement
are tightly packed, particles are touching each other
vibrate about their position
have strong forces of attraction holding them in position

Question 2

properties of liquids

Answer 2

no fixed shape, but take the shape of their container
fixed volume
can flow
cannot be compressed

have no regular arrangement
are tightly packed, particles are touching each other
move randomly at different speeds
do not move far as they frequently collide with other particles
have weaker forces of attraction compared to solids

Question 3

properties of gases

Answer 3

no fixed shape, but take the shape of their container
do not have a fixed volume, but take up the volume of their container
can flow
can be compressed

have no regular arrangement
move randomly at different speeds, but much faster than liquids
have very weak forces of attraction compared to solids

Question 4

Forces of attraction

Answer 4

Forces that exist between atoms or molecules that pull or attract the particles to each other. Known as intermolecular forces.

Question 5

particle model

Answer 5

A theoretical model to explain the arrangement and movement of particles in all states of matter.

Question 6

summary of changes of state

Answer 6

…to solid …to liquid …to gas
From solid… – melting (sublimation)
From liquid.. freezing – evaporating
From gas… (deposition) condensing –

Question 7

kinetic particle theory

Answer 7

A theory used to describe and explain the behaviour of substances in each state of matter. The fundamental premise to kinetic theory is that particles are always moving.

Question 8

kinetic energy

Answer 8

A store of energy transferred when an object moves. Object moving quickly have more kinetic energy than those moving slowly.

Question 9

solid to liquid (melting)

Answer 9

Particles in the solid state vibrate around a fixed point.
As more energy is supplied, the vibrations of the particles increase.
When particles have enough energy to overcome the forces of attraction, they begin to move past each other.

Question 10

liquid to gas (boiling)

Answer 10

Particles in the liquid state move past each other.
As more energy is supplied, the particles gain energy and move faster.
When particles have enough energy, they overcome the forces of attraction and break free from the liquid.

Question 11

gas to liquid (condensation)

Answer 11

Particles in the gaseous state move freely, quickly and randomly.
As the gas cools, energy is removed.
The particles slow down.
Eventually, they no longer have enough energy to overcome the forces of attraction.

Question 12

liquid to solid (freezing)

Answer 12

Particles in the liquid state overlap and move past each other.
As the liquid cools, more energy is removed from the particles and they slow down.
The forces of attraction pull the particles together into a regular arrangement.
The particles remain in their positions and vibrate around a fixed point.

Question 13

pressure

Answer 13

A measure of the force which the particles in a container exert on the surface as the particles collide with it.

Question 14

concentration gradient

Answer 14

The difference in concentration of a fluid (liquid or gas) between two connected areas.

Question 15

diffusion

Answer 15

is the movement of particles from an area of high concentration to an area of low concentration and continues until the concentration of the gas is uniform throughout.

Question 16

exothermic reaction

Answer 16

A reaction that gives out energy to the surroundings, usually as heat.

Question 17

endothermic reaction

Answer 17

A reaction that takes in energy from the surroundings, usually as heat.

Question 18

neutralisation reactions

Answer 18

A reaction between an acid and a base or an alkali to produce a neutral salt and water.

Question 19

reaction pathway diagrams

Answer 19

Graphical method for showing the changes in energy levels during a chemical reaction.

Question 20

activation energy

Answer 20

The minimum energy required for a reaction to happen.

Question 21

enthalpy change

Answer 21

The difference in energy between reactants and products. Units in kJ/mol with symbol ΔH .

Question 22

surplus

Answer 22

Excess or extra.

Question 23

bond energy

Answer 23

The amount of energy in kJ/mol that is needed to break one mole of a bond.

Question 24

saturated

Answer 24

Molecules that contain only single carbon to carbon bonds.

Question 25

covalent bonds

Answer 25

A force of attraction between shared pairs of electrons and the nuclei of two atoms.

Question 26

functional group

Answer 26

An atom of a group of atoms in an organic compound that gives rise to the particular chemical reactions of that compound.

Question 27

incomplete combustion

Answer 27

When combustion of a substance occurs with insufficient oxygen. If carbon-containing substances are being combusted then carbon monoxide will be produced.

Question 28

substitution reactions

Answer 28

A chemical reaction when an atom on a molecule is replaced by another.

Question 29

choloroalkanes

Answer 29

Organic compounds produced by the substitution reaction between chlorine and alkanes.

Question 30

monosubstitution

Answer 30

A substitution reaction in which only one hydrogen is replaced by another type of atom. For example, chloromethane.

Question 31

fermentation

Answer 31

A chemical reaction that is used to convert glucose into alcohol with the use of yeast as a catalyst.

Question 32

addition reaction

Answer 32

The chemical reaction when a double bond is broken in an alkene resulting in the addition of atoms to the molecule.

Question 33

volatile

Answer 33

The property of a material describing how easily it vaporises (evaporates).

Question 34

biofuel

Answer 34

Fuels derived from plant based materials such as bioethanol and biodiesel. They have the advantage over conventional fossil fuels of being renewable.