Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

chemistry > topic 2 > Flashcards

topic 2 Flashcards

1
Q

solids

A

there are strong forces of attraction between particles which hold them in fixed positions in a regular lattice fragment

  • don’t move, fixed positions
  • don’t have much energy
  • vibrate on a spot
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

liquids

A
  • some force of attraction between the particles
  • free to move past each other but still touching
  • not a definite shape and volume
  • more energy
  • constantly moving in a random shape
  • hotter the liquid gets the faster it moves
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

gases

A
  • no force of attraction
  • travel in a straight line and only interact when they collide
  • don’t keep a definite shape or volume
  • always will a container, exert pressure of the walls
  • more energy
  • hotter the gas the faster they move
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

liquid to solid

A

freezing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

solid to liquid

A

melting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

liquid to gas

A

evaporating

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

gas to liquid

A

condensing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

solid to gas

A

subliming

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

gas to solid

A

deposition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

when a solid is heated…

A

particles gain more energy
they vibrate more
weakens forces making the solid expand
at a certain temperature the particles have enough energy to break free from their positions (melting) and the solid turns into a liquid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

when a liquid is heated

A
  • the particles get even more energy
  • this energy makes the particles move faster which weakens and breaks the bond holding holding the liquid together
  • at a certain temp the particles have enough energy to break their bonds. This is called evaporation and the liquid turns into a gas
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

chemical changes for atoms

A

atoms are rearranged during chemical reaction

  • chemical changes are different to physical changes
  • chemical changes happen during chemical reactions when bonds between atoms break and the atoms change places.
  • the atoms from the substances you start off with (the reactants) are rearranged to form different substances (the products)
  • chemical changes are often hard to reverse
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

pure substances

A
  • a substance is pure if it’s completely made up of a single element or
    compound
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

mixtures

A

if you’ve got more than one compound present or different elements that aren;t all part of a single compunds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

testing for purity

A

you can test for purity using melting points

  • every pure substances has a specific, sharp melting and boiling point
  • MIXTURES will melt gradually over a range of temperatures
  • PURE substances have sharp melting points
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is distillation

A

used to separate mixtures that contain liquids. Two types: simple and fractional

17
Q

what is simple distillation

A

used for separating out a liquid from a solution
For example, water can be separated from salt solution by simple distillation. This method works because water has a much lower boiling point than salt. When the solution is heated, the water evaporates. It is then cooled and condensed into a separate container. The salt does not evaporate and so it stays behind.

18
Q

what is fractional distillation

A

Fractional distillation is a method for separating a liquid from a mixture of two or more liquids. For example, liquid ethanol can be separated from a mixture of ethanol and water by fractional distillation. This method works because the liquids in the mixture have different boiling points. When the mixture is heated, one liquid evaporates before the other.

19
Q

what is filtration

A

if the product of a reaction is an insoluble solid, you can use filtration to separate it out from the liquid reaction mixture
- put some filter paper into a funnel and pour in your mixture. The liquid part of the mixture runs through the paper leaving behind a solid residue

20
Q

crystallisation

A

separates a soluble solid from a solution
To obtain large, regularly shaped crystals:

put the solution in an evaporating basin
warm the solution by placing the evaporating basin over a boiling water bath
stop heating before all the solvent has evaporated
After the remaining solution has cooled down, pour the excess liquid away (or filter it). Dry the crystals using a warm oven or in air.

21
Q

chromatography

A

a method used to separate a mixture of soluble substances and identify them

there are two phrases: mobile phase and
stationary phase

22
Q

chromatography mobile phase

A

where the molecules CAN move. This is always a liquid or a gas

23
Q

chromatography stationary phase

A

where the molecules CAN’T move. This can be a solid or a really thick liquid

24
Q

mixtures in mobile and stationary phase

A

the components in the mixture separate out as the mobile phase moves over the stationary phase - they all end up in different places in the stationary phase
- this happens because the chemicals spend different amounts of time dissolved in the mobile phase and stick to the stationary phase.

25
Q

paper chromatography

A

in paper chromatography the stationary phase is a piece of filter paper and the mobile phase is a solvent (e.g water or ethanol)
a pure substance produces one spot on the chromatogram
an impure substance produces two or more spots

26
Q

stages in paper chromatography

A

the stationary phase, which in paper chromatography is very uniform, absorbent paper
the mobile phase is the solvent that moves through the paper, carrying different substances with it

molecules with higher solubility (less attracted to the paper) will spend more time in the mobile phase

27
Q

method for paper chromatography

A
  1. line at the bottom of the paper
  2. draw spots of the line
  3. dip paper in breaker with solvent
  4. the solvent will start to move up the paper
  5. see spots forming at different points on the paper
28
Q

calcualting Rf

A

distance travelled by solute/ distance travelled by solvent

ratio between the distance travelled by the dissolved substances (solute) and the distance travelled by the solvent

29
Q

3 water purifying treatments

A

filtration
sedimentation
chlorination

30
Q

filtration (water)

A

a wire mesh screens out large twigs and then gravel and sand beds filter out any other solid bits

31
Q

sedimentation (water)

A

iron sulfate or aluminium sulfate is added to the water, which makes fine particles clump together and settle at the bottom

32
Q

chlorination (water)

A

chlorine gas is bubbled through to kill harmful bacteria and other microbes

33
Q

why can normal water give a false result

A

it has small amounts of ions (such as calcium, iron and copper) that can interfere with reactions

deionised water is used instead - ions have been removed

34
Q

purifying sea water

A

simple distillation

  • sea water is heated so that water vapour leaves it quickly
  • the water is then cooled and condensed forming water without the dissolved salts
35
Q

water for drinking

A

water from water source - sedimentation tank (small particles settle out) - filtration 9using tanks containing beds of sand and gravel) - choline is added in a process called chlorination (kills microorganisms in the treated water)

chemistry (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions