M, A! T! T? E. R

Question 1

Homogeneous mixtures

Answer 1

Are Uniform mixtures
All the constituents are in the same phase so that none of them can be clearly identified from others.

Eg sugar in water and air mixture of oxygen and nitrogen gases.

A form of separation : distillation

Question 2

Heterogeneous mixtures

Answer 2

Non uniform mixtures
Consists of substances of different phases mixed together and substances which can be clearly identified in the mixture.

Eg oil mixed with water : oil separates front water meaning they are immiscible.
Form of separation : hand sorting

Question 3

Elements

Answer 3

Simplest type of pure substance which cannot be broken down by chemical reactions into any simpler types of substances.
Eg. Oxygen(O) - (02) and iron (FE)

Question 4

Solutions

Answer 4

Homogenous mixture which is the same throughout.
One substance (solute) dissolves in another substance (solvent).
Can be made up of compounds/elements.
No fixed composition.
Separated by physical means such as evaporation and filtration.
Eg saltwater and sugar dissolved in water.

Question 5

Compounds

Answer 5

Pure substance made of two or more elements bonded in a fixed ratio by a chemical reaction.
Chemical composition of compounds is fixed:substances are bonded a constant ratio.
Compounds can be broken down into simpler substances only by chemical reactions such as electrolysis.
E. G water(H20) and sodium chloride (NaCl)

Question 6

Conductivity

Answer 6

Refers to the ability of a material to conduct electricity or heat

Question 7

Types of conductivity

Answer 7

Electricity and thermal conductivity

Question 8

Electrical conductivity

Answer 8

Ability of a material to allow the flow of electric current depending on the presence of free charges (electrons or ions) that can move through the material.

Metals are good electric conductors
Ionic compounds conduct electricity when dissolved in water or molten as the ions can move freely

Question 9

Thermal conductivity

Answer 9

Ability of a material to conduct heat dependent on how well particles in a substance can transfer energy from one to the another

Metals like copper and aluminum because of the their closely packed particles and energy is transferred efficiently through vibration

Insulating materials such as rubber/wood have low thermal conductivity because the particles are not closely packed preventing the easy transfer of heat

Question 10

Factors affecting conductivity

Answer 10

Material type, temperature and purity

Question 11

Material type

Answer 11

Metals and Ionic compounds tend to have higher electrical conductivity than non metals

Question 12

Temperature

Answer 12

Electric conductivity decreases as temperature increases (except semi conductors where temperature increases and conductivity increases)

Question 13

Purity

Answer 13

Impurities in a material can disrupt the flow of electric current/heat reducing its conductivity