chemical change ch8

Question 1

physical properties

Answer 1

properties that you can either observe using your five senses — seeing, hearing, touching, smelling and tasting — or measure directly

Question 2

chemical properties

Answer 2

properties that describe how a substance combines with other substances to form new chemicals or how a substance breaks up into two or more different substances

Question 3

flammability

Answer 3

an indicator of how easily a substance catches fire

Question 4

reactivity

Answer 4

a measure of how likely a particular metal is to take part in a displacement reaction

Question 5

toxicity

Answer 5

the danger to your health caused when poisonous substances combine with chemicals in your body to produce new substances and damaging effects

Question 6

Sublimation

Answer 6

a chemical process where a solid turns into a gas without going through a liquid stage.

Question 7

melting

Answer 7

something that has become liquefied by heating.

Question 8

evaporation

Answer 8

the process of turning from liquid into vapour.

Question 9

solid

Answer 9

a hard object that is firm and stable in shape

Question 10

Freezing

Answer 10

a phase transition in which a liquid turns into a solid when its temperature is lowered below its freezing point, also known as solidification.

Question 11

liquid

Answer 11

a substance that flows freely but is of constant volume, having a consistency like that of water or oil.

Question 12

condensation

Answer 12

water which collects as droplets on a cold surface when humid air is in contact with it

Question 13

gas

Answer 13

an air-like fluid substance which expands freely to fill any space available, irrespective of its quantity.

Question 14

Desublimation

Answer 14

the phase change from gas directly to solid, with no intermediate liquid phase.

Question 15

deposition

Answer 15

the phase change from gas directly to solid, with no intermediate liquid phase.

Question 16

Solidification

Answer 16

a phase change of matter that results in the production of a solid. also known as freezing

Question 17

reaction rate

Answer 17

speed at which a reaction takes place

Question 18

catalyst

Answer 18

chemical that helps to start or speed up a chemical reaction

Question 19

chemical change

Answer 19

change that results in a new substance being formed. During a chemical change, some chemical bonds break and others form.

Question 20

evaporates

Answer 20

change state from a liquid to a gas. Evaporation occurs only from the surface of a liquid.

Question 21

chemical reaction

Answer 21

a chemical change in which one or more new chemical substances are produced

Question 22

reactants

Answer 22

chemical substance used up in a chemical reaction. Some chemical bonds in a reactant are broken during the reaction.

Question 23

products

Answer 23

new chemical substance that results from a chemical reaction

Question 24

precipitate

Answer 24

solid product of a chemical reaction that does not dissolve in water

Question 25

rusting

Answer 25

the corrosion of iron

Question 26

corrosion

Answer 26

a chemical reaction that wears away a metal. Air, water or chemicals in air and water, as well as many household substances, can be corrosive. Many acids and other corrosive substances are dangerous.

Question 27

rust

Answer 27

a brown substance formed when iron reacts with oxygen and water

Question 28

surface protection

Answer 28

coating over a metal surface to prevent corrosion

Question 29

galvanising

Answer 29

protecting a metal by covering it with a more reactive metal that will corrode first

Question 30

burning

Answer 30

combining a substance with oxygen in a flame

Question 31

oxidation

Answer 31

chemical reaction involving the loss of electrons by a substance

Question 32

fossil fuel

Answer 32

substance, such as coal, oil and natural gas, that has formed from the remains of ancient organisms. Coal, oil and natural gas are often used as fuels; that is, they are burnt in order to produce heat.

Question 33

combustion

Answer 33

the process of combining with oxygen, most commonly burning with a flame