States of Matter and Separation Techniques

Question 1

what are intermolecular forces?

Answer 1

attractive forces between molecules which hold the substance together.

Question 2

what does evaporation separate?

Answer 2

soluble solids from solutions.

Question 3

what is boiling?

Answer 3

When the liquid is heated, and absorbs more energy and it boils, turning into a gas.

Question 4

solid - liquid

Answer 4

melting

Question 5

liquid - gas

Answer 5

evaporation

Question 6

gas - liquid

Answer 6

condensation

Question 7

liquid - solid

Answer 7

freezing

Question 8

what is sublimation?

Answer 8

when a solid turns directly into a gas.

Question 9

why does hot water evaporate faster than cold water?

Answer 9

• particles have more kinetic energy.
• therefore, can overcome attractive forces (intermolecular) between water molecules.

Question 10

what is the arrangement and movement of particles in a solid?

Answer 10

• fixed position
• arranged in rows
• all touching
• vibrate

Question 11

what is the arrangement and movement of particles in a liquid?

Answer 11

• all touching
• no fixed shape
• random arrangement
• take the shape of the container
• flow

Question 12

what is the arrangement and movement of particles in a gas?

Answer 12

• random arrangement
• not touching
• spread out
• no fixed shape
• flow
• can collide

Question 13

what is diffusion?

Answer 13

the movement of particles from an area of high conc to an area of low conc.

Question 14

why does temperature affect diffusion?

Answer 14

heating particles gives them more kinetic energy so they diffuse and spread out quicker.

Question 15

why does state of matter affect diffusion?

Answer 15

liquids diffuse slower than gases as liquid particles are touching so there is less space for them to move.

Question 16

why does size and mass of particles affect diffusion?

Answer 16

smaller particles are lighter so travel faster, so smaller particles diffuse further than larger ones in the same time.

Question 17

in an experiment, a gas jar full of brown bromine gas is separated from a gas jar full of air by a glass plate.

the glass plate is removed. describe and explain the appearance of the gas jars after an hour.

Answer 17

the bromine gas and air particles diffuse and the whole tube will be a light brown colour.

Question 18

what is an element?

Answer 18

one type of atom either on its own or bonded to the same type of atom.

Question 19

what is a compound?

Answer 19

a substance made up of 2 or more different types of atoms bonded together.

Question 20

what is a mixture?

Answer 20

a substance made up of 2 or more atoms covalently bonded together.
can be elements or compounds.

Question 21

what is filtration used for and give an example?

Answer 21

to separate a liquid and an insoluble solid.
eg water and sand.

Question 22

the water particles are small enough to fit through the holes in filter paper during filtration, what is the water called?

Answer 22

filtrate.

Question 23

the sand particles are too big to fit through the holes in the filter paper during filtration, what is the sand called?

Answer 23

residue.

Question 24

what are 3 uses of filtration?

Answer 24

• sand filters/oil filters
• coffee machines
• draining pasta

Question 25

what is the method for filtration?

Answer 25

• grind up rock salt (makes it easier to dissolve) use a pestle and mortar
• add water and stir (only salt dissolves)
• filter the resulting mixture
• heat solution (to evaporate the water and causes salt to crystallise)

Question 26

what is distillation used for?

Answer 26

to obtain and separate liquids from a solution using both evaporation and condensation.

Question 27

what does the substance with the lower boiling point do during distillation?

Answer 27

evaporates and then is condensed back to water into a beaker.

Question 28

what does the substance with the higher boiling point do during distillation?

Answer 28

remains in the round bottomed flask.

Question 29

what is fractional distillation used for?

Answer 29

to separate a number of liquids.

Question 30

what does solvent mean and give an example?

Answer 30

able to dissolve other substances
eg water

Question 31

what is chromatography used for?

Answer 31

to separate a mixture of two or more substances that are soluble.

Question 32

what does the more soluble substance in chromatography do?

Answer 32

move further and faster up the paper.

Question 33

what is the substance if it does not move in chromatography?

Answer 33

insoluble in that solvent (so you use another solvent)

Question 34

what is the definition of the retention factor?

Answer 34

the ratio of the distance moved by a substance to the distance moved by the solvent. it is always less than 1.
ie how soluble your inks are.

Question 35

what is the calculation for retention factor?

Answer 35

distance travelled by substance
DIVIDED BY
distance travelled by solvent

Question 36

Why is the baseline drawn in pencil rather than pen?

Answer 36

ink is soluble so will dissolve in the water and affect the results. pencil is insoluble.

Question 37

how can flammable substances be heated safely?

Answer 37

using a hot water bath.

Question 38

why should the water level be below the dye in chromatography?

Answer 38

they would dissolve into the water if it was above the dye instead of up the paper.