Elements, compounds, and mixtures

Question 1

Define element:

Answer 1

Pure substance, simplest form of matter that cannot be broken down further

Question 2

Define compound:

Answer 2

Pure substance made of two or more elements; cannot be separated physically

Question 3

Three properties of mixtures:

Answer 3

1. No fixed ratio of components
2. No fixed boiling point
3. Can be separated physically
4. Parts maintain their individual properties

Question 4

One example and definition of homogenous mixtures:

Answer 4

Steel/salt water

1. No visible boundaries
2. Equal and even distribution of parts

Question 5

One example and definition of heterogenous mixtures:

Answer 5

Oil and water/carbonated water/cereal

1. Clearly defined boundaries

Question 6

Conditions and steps of filtration:

Answer 6

Non-soluble solid AND solvent

1. Pour mixture into filter paper fitted into a funnel
2. Solvent goes through pores into beaker at bottom (filtrate)
3. Solid remains in filter paper (residue)

Question 7

Conditions and steps of evaporation:

Answer 7

Soluble solid AND solvent

1. Heat solution in evaporation dish
2. Solvent is released as vapour
3. Solute remains

Question 8

Conditions and steps of solvation:

Answer 8

Soluble solid AND insoluble solid

1. Dissolve soluble solid in solvent
2. Filter out insoluble solid
3. Evaporate mixture to return soluble solid

Question 9

Conditions and steps of distillation:

Answer 9

Two liquids with different boiling points

1. Heat mixture in beaker
2. Liquid with lower boiling point evaporates and travels through condenser
3. Condenser turns gas back into liquid to be collected in second beaker

Question 10

Conditions and steps of paper chromatography:

Answer 10

Mixture of solutes

1. Dissolve mixture in solvent (mobile phase)
2. Place chromatography paper in solution
3. More soluble = travels further up paper; less soluble = travels less

Question 11

Conditions and steps of recrystallization:

Answer 11

Impure solid

1. Place mixture into hot solvent and dissolve
2. Filter out impurities
3. Slowly cool solid back down, forming pure crystals and leaving impurities in the solution

Question 12

Equipment required for filtration:

Answer 12

Funnel, filter paper, two beakers, stand

Question 13

Equipment required for evaporation:

Answer 13

Heat source, evaporation dish, gauze

Question 14

Equipment required for distillation:

Answer 14

Distillation apparatus (flask, condenser), heat source, two beakers, thermometer

Question 15

Define allotrope with example:

Answer 15

Alternative form of an elemental substance: e.g. carbon as diamond