particles

Question 1

what does soluble mean?

Answer 1

a substance that can dissolve

Question 2

what does insoluble mean?

Answer 2

a substance that cannot dissolve

Question 3

what is a solute?

Answer 3

a substance that dissolves (usually a solid)

Question 4

what is a solvent?

Answer 4

a substance that the solute dissolves in (usually a liquid)

Question 5

what does saturated mean?

Answer 5

a mixture in which no more solute can dissolve

Question 6

what is a solution?

Answer 6

a mixture of a solvent and a solute

Question 7

what is a suspention?

Answer 7

an insoluble solid in a liquid

Question 8

what does dissociate mean?

Answer 8

particles separate and they are no longer touching

this usually happens when a substance dissolves

Question 9

what is solubility measured in?

Answer 9

grams per 100 cm cubed

Question 10

describe the relationship between solubility and temperature

Answer 10

when a solid dissolves, its particles dissociate. this process requires lots of energy due to the strong forces between particles

at higher temps, the forces are weaker, so MORE particles dissociate

higher temps = higher solubility

Question 11

what happens to the solubility of gases when temp increases?

Answer 11

SOLUBILITY DECREASES

the particles spread out further at higher temps, as they spread out it is harder to remain dissolved in the liquid

Question 12

what is the general method for measuring solubility?

Answer 12

1. measure x amount of solvent in measuring cylinder
2. add excess solid and allow to dissolve (heat to speed up, water evaporates and solubility increases)
3. filter and collect residue (y)
4. x - y = solubility

Question 13

what is a second method of measuring solubility?

Answer 13

1. record mass of conical flask (144.1g)
2. measure 25cm cubed of water into the flask
3. re record the mass (168.26g)
4. add excess solid and leave it to dissolve
5. use water bath to maintain temp at 20 degrees C
6. filter mixture (water remains on filter paper)

Question 14

what can distillation be used to separate?

Answer 14

any solid from a liquid

if the solid is insoluble filtering is much easier but soluble solids in liquids are harder

distillation is used when the solvent is required, for example desalination

Question 15

when 2 liquids are mixed together, when can distillation also be used?

Answer 15

liquids are miscible (form one FASE)

liquids have different bpts

Question 16

what is distillation with 2 liquids called?

Answer 16

fractional distillation

Question 17

how are immiscible liquids separated?

Answer 17

using a separating funnel

Question 18

how are miscible liquids separated?

Answer 18

fractional distillation (different boiling points=
chromatography (different solubilities)

Question 19

describe the full method for chromatography

Answer 19

1. place 2cm^3 of solvent in a beaker
2. draw a pencil line 2.5cm from bottom of paper
3. place one drop of mixture on base line
4. stand paper in solvent and cover beaker
5. leave until solvent is around 1cm^3 from top
6. draw line to show solvent distance (solvent front)
7. dry paper with hot plate

Question 20

why do the components separate in chromatography?

Answer 20

due to the difference in attraction to solvent particles

if there is a stronger attraction (MORE SOLUBLE) the particles move further

Question 21

how do you calculate retention factor for chromatography?

Answer 21

distance of component/distance of solvent

answer should be a decimal

Question 22

what is the definition of diffusion?

Answer 22

the RANDOM MOVEMENT of particles that causes them to spread out and mix (with a NET movement from higher to lower concentration)

Question 23

describe in detail the 4 steps of diffusion

Answer 23

1. the particles in the solid dissociate and DISSOLVE in the water (only happens in solids)
2. water particles and dissociated solid slide over each other and mix, occurs at surface of crystal
3. the random movement of particles causes them to gradually spread out
4. once “equally spread” the particles continue to move randomly but there is no change in NET movement

Question 24

what are the 2 factors diffusion depends on?

Answer 24

temperature

size/mass of particles

Question 25

what happens to the rate of diffusion when you increase temperature?

Answer 25

diffusion rate increases because particles gain energy and move faster

gases diffuse faster as more particles move faster

Question 26

why do larger particles diffuse slower?

Answer 26

with the same energy larger particles move slower

Question 27

how can a precipitation reaction be used to show diffusion?

Answer 27

ammonia and hydrogen chloride

use an open tube, put a cotton ball with ammoniA on one side and hydrogen chloride on the other

the solid ammonium chloride will form when the particles met, closer to the HCl because the ammonia particles are smaller and therefore diffuse faster

Question 28

whwy will ammonium chloride form closer to the HCl?

Answer 28

cause HCl particles are bigger, and diffuse slower than NH3