Chemistry (Solutions and Mixtures)

Question 1

Element

Answer 1

Contains one type of atom, which may occur individually or bonded to form molecules

Question 2

Compound

Answer 2

Two or more elements that are chemically bonded together (DO NOT APPEAR IN PERIODIC TABLE)

Question 3

Mixture

Answer 3

Contains at least two different substances (elements and/or compounds) NOT bonded chemically

Question 4

Are mixtures pure or impure?

Answer 4

Impure

Question 5

Are compounds and elements pure or impure?

Answer 5

Pure

Question 6

What is easier to separate: mixtures or elements that make up a compound?

Answer 6

Mixtures

Question 7

Physical change

Answer 7

Rearranging particles, but individual particles are not changed in any way

Question 8

Are physical changes reversible?

Answer 8

Yes

Question 9

What is an example of a physical change?

Answer 9

Separating mixtures

Question 10

Solute

Answer 10

The substance being dissolved

Question 11

Solvent

Answer 11

The liquid it’s being dissolved in

Question 12

Miscible liquids

Answer 12

Liquids that mix together (i.e water and squash)

Question 13

Immiscible liquids

Answer 13

Liquids that don’t mix together (i.e water and oil)

Question 14

What is a separating funnel used for?

Answer 14

Separate immiscible liquids by opening the tap to remove the denser liquid.

Question 15

Distillation

Answer 15

Process for separating two or more miscible liquids, making use of their different boiling points.

Question 16

What happens in the process of distillation?

Answer 16

When the first liquid boils (the one with
the lower boiling point), its vapour
passes upwards, into the condenser,
where it is cooled, condensing it to
form a liquid which is collected in the
beaker.

Question 17

Does the liquid with the higher boiling point or the liquid with the lower boiling point stay in the flask?

Answer 17

Higher boiling point

Question 18

What happens if more than 2 miscible liquids are mixed together?

What process is used to separate/identify the liquids?

Answer 18

A thermometer may be used to identify each liquid as it boils.

Question 19

What can distillation be used for?

Answer 19

Purification (impurities stay in the flask) or increasing the concentration in a liquid

Question 20

What happens if the two liquids have very similar boiling points?

Answer 20

Slightly different apparatus is used for fractional distillation. A longer column is used for more space for separating the two liquids.

Question 21

What is fractional distillation useful for?

Answer 21

Separating crude oil from chemicals so that they can be used separately

Question 22

Filtration

Answer 22

Using a filter funnel
Used for separating insoluble solids from liquids
The liquid’s particles are small enough to get through, the solid’s particles isn’t

Question 23

Decantation

Answer 23

Pouring off the liquid to leave the solid behind

Question 24

What is the filter funnel lined with?

Answer 24

Filter paper

Question 25

What is left behind after filtration?

Answer 25

Solid residue

Question 26

What is the liquid that passes through the filter funnel called?

Answer 26

Filtrate

Question 27

What is the process of separating a soluble solid from the solvent called?

Answer 27

Evaporation

Question 28

Evaporation

Answer 28

Use evaporation basin Evaporate quickly (with the help of a heat source) or slowly (by leaving the mixture for a few days)

Question 29

Crystallisation

Answer 29

Aftermath of evaporation Crystals of the solute formed on the walls of the basin The slower the rate of evaporation, the larger the crystals

Question 30

Chromatography

Answer 30

Chromatography is a method of separating a number of soluble substances from the same mixture. Each of the solutes is carried by the solvent (usually water) across the paper.

Question 31

Chromatogram

Answer 31

A chromatogram is the pattern made on the filter paper during a chromatography experiment. The more soluble the solvent, the further it will travel before leaving its mark.

Question 32

What can chromatography be used for?

Answer 32

This technique can be used for comparing mixtures, such as identifying ink or paint samples – we can match the positions of the marks on the chromatogram to identify similar substances in each mixture.