section 1 ABC Flashcards

need to practice solubility curves

1
Q

what are the three states of matter?

A

solid, liquid, gas

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2
Q

what does each state depend on? what does this factor depend on?

A

how strong the forces of attraction are between the particles of the material. this depends on material, temperature, pressure

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3
Q

describe the arrangement of forces within a solid.

A
  1. in solids, there are strong forces of attraction between particles which hold them close together in fixed positions to form very regular lattice arrangments
  2. the particles don’t move from their positions, so all solids keep a definite shape and volume, and don’t flow like liquids
  3. the particles vibrate more about their positions and the hotter the solid becomes, the more they vibrate (causing the solids to expand slightly when heated)
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4
Q

describe the arrangement of forces within a liquid.

A

in liquids, there is a weak force of attraction between the particles. they’re randomly arranged and free to move past each other, but they tend to stick closely together
2. liquids have a definite volume but don’t keep a definite shape and will flow to fill the bottom of a container
3. the particles are constantly moving with random motion. the hotter the liquid gets, the faster they move. this causes the liquid to expand lightly when heated

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5
Q

describe the arrangement of forces within a gas.

A
  1. in gases, the forces of attraction between particles are very weak and they’re free to move and are far apart. the particles in gases travel in straight lines.
  2. gases don’t keep a definite volume or shape and will always fill any container
  3. the particles move constantly in random motion. the hotter the gas gets, the faster they move. Gases either expand when heated or their pressure increases
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6
Q

what is the name for a gas going to a liquid?

A

condensing (condensation)

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7
Q

name for liquid to gas?

A

evaporation

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8
Q

liquid to solid name?

A

freezing

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9
Q

solid to liquid name?

A

melting

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10
Q

solid to gas name?

A

sublimation (subliming)

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11
Q

what happens if a solid is heated?

A

When a solid is heated, its particles gain more energy.
This makes the particles vibrate more (aka faster), which weakens the forces that hold the solid together. this makes the solid expand
at a certain temp, the particles have enough energy to break free from their positions as the forces of attraction are no longer strong enough to hold them together.
this is called melting and the solid turns into a liquid

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12
Q

why does energy have other be supplied when converting something from a solid to a liquid?

A

this is because the particles in a liquid have more kinetic energy than particles in a solid so energy has to be supplied in tho convert the solid into a liquid

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13
Q

what happens from solid to liquid?

A

the liquid is cooled. the particles will move around more slowly until they move so slowly that the forces of attraction between them will hold them in a fixed position and the particles pack more closely together in a solid.
the liquid freezes, forming a solid.
the temp at which this occurs it the freezing point

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14
Q

what happens when a liquid is heated?

A

the particles get more energy. this makes them move faster which weakens and breaks the bonds holding the liquid together
at a certain temp, the particles have enough energy to break their bonds.
at this point, the liquid is evaporating the the liquid turns into a gas

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15
Q

what is boiling?

A

it occurs when a liquid is heated so strongly that the particles are moving fast enough to overcome all forces of attraction between them
the stronger the forces of attraction between the particles, the higher the boiling point of the liquid.
this is because more energy is needed to overcome these forces of attraction

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16
Q

what is evaporation?

A

in any liquid or gas, the average speed of particles varies with temp. but at each temp, some particles will be moving faster than the average particle and others more slowly.

some very fast particles at the surface of the liquid will have enough energy to overcome the forces of attraction between the particles and they will break away to form a gas.
note: here you don’t see any bubbling, it just slowly disappears. it the liquid is in a container,so evaporation and condensation will occur because the particles collide with the surface of the liquid aswell

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17
Q

when can evaporation occur?

A

at any temp. e.g., puddles evaporated at 5 degrees not at their boiling point which is 100 degrees

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18
Q

what is gas to solid called?

A

deposition

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19
Q

how would you be able to tell the physical state of a substance by knowing its boiling/melting point?

A

below melting - solid
above melting - liquid
below boiling - liquid
above boiling - gas

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20
Q

what is diffusion?

A

Diffusion is the random movement of particles from a region of their high concentration to a region of their low concentration down the concentration gradient.
FORMAL DEFINITION:
Diffusion is the spreading out of particles form where they are at a high concentration to where they are at a low concentration

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21
Q

describe a practical to see diffusion.

A

get a beaker of water and place potassium manganate (VII) at the bottom
- the purple colour slowly spreads to fill the beaker
- the particles are diffusing out among the water particles
- it is the random motion of particles in a liquid that causes the purple colour to eventually spread out through water
note this can take days because the particles in a liquid move more slowly than particles in a gas

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22
Q

describe a practical to show that particles of different gases travel at different speeds

A
  • aqueous ammonia (NH3) gives off ammonia gas. HCl gives off hydrogen chloride gas
  • get a glass of tube and put a piece of cotton wool soaked in concentrated ammonia solution on one end and a source of cotton wool soaked in concentrated hydrochloric acid on the other end. close each side with a bung
  • both particles diffuse along the tube
  • a ring of solid ammonium chloride forms where they meet. this ring takes time to form and appears closer to the hydrochloric acid end.
  • this is because ammonia particles are lighter and therefore move faster
    and therefore travel further in the same amount of time
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23
Q

how else can you show the diffusion of a gas?

A
  • you can put bromine in the first half od a glass jar. bromine is a brown strongly smelling gas
  • fill the other half with air and separate the gases with a glass plate
  • when the remove the plate, you’ll see the brown bromine gas slowly diffuse through the air
  • the random motion means that the bromine will eventually diffuse right through the air
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24
Q

what is a solute?

A

a substance that dissolves in a solvent

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25
Q

what is a solvent?

A

the liquid in which a solute dissolves.

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26
Q

what is a solution?

A

the mixture of the dissolved solute and the solvent it is dissolved in

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27
Q

what is a saturated solution?

A

A saturated solution is one in which no more solid can dissolve in the liquid at a given temperature.
(must be some undissolved solid present to make it saturated)

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28
Q

what happens in a solution?

A

the attractive forces in the solute are being broken. at the same time, new attractive forces are being formed between the solvent particles and the solute particles.

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29
Q

what makes a particular solid soluble or not?

A

depends on whether the new attractive forces are strong enough to overcome the old ones

30
Q

what does the solubility of a solid in a solvent at a particular temperature refer to?

A

‘the mass of solute which must dissolve in 100g of solvent at that temperature to form a saturated solution’

31
Q

practice reading solubility curves

A

a solubility curve shows how solubility of a solid changes with temp

32
Q

how do you plot a solubility curve?

A

solubility / g per 100g of water - y axis
temperature in degrees celsius - x axis

33
Q

describe a practical where you can investigate the solubility of a solid in water at a specific temperature.

A

Here’s how you would investigate how the solubility of ammonium chloride (a solid) is affected by temperature:
1) Make a saturated solution by adding an excess of ammonium chloride to 10 cm^3 of water in a boiling tube.
You will know when ammonium chloride is in excess because it will start to sink to the bottom of the tube.
1. Give the solution a good stir and place the boiling tube in a water bath set to 25 °C.
2. After 5 minutes, check that all of the excess solid has sunk to the bottom of the tube and use a
ammonium chloride solution
thermometer to check that the solution has reached 25 °C.
1. Weigh an empty evaporating basin. Pour some of the solution into the basin, making sure not to pour in any of the undissolved solid.
2. Re-weigh the basin and its contents, then gently heat it
evaporating basin
Bunsen-
using a Bunsen burner to remove all the water.
burner
If you heat the basin too strongly, some of the ammonium chloride might turn into a gas and escape.
This will cause the mass of solid in the basin to decrease, and your solubility value will be lower than it should be.
6) Once all the water has evaporated, you’re left with pure ammonium chloride.
Re-weigh the evaporating basin and its contents.
Repeat steps 1-6 twice more, but with the water bath at different temperatures (e.g. 35 °C and 45 °C).
1. You can use the different masses to work out the solubility at each temperature — see below.
2. You could plot the results on a graph like the one on the previous page.

34
Q

how can you calculate solubility from the masses of the solid and water?

A

solubility (g per 100g of solvent) = (mass of solid (g) / mass of water removed (g)) x 10

35
Q

what is an element

A

a pure substance made up of only one type of atom, with all atoms having the same number of protons

36
Q

what is a compound?

A

a pure substance made up of two or more elements that are chemically bonded together in fixed ratios

37
Q

what is a mixture?

A

a combination of two or more substances that are not chemically joined together

38
Q

what is the relative mass of a proton, neutron, electron?

A

p-1,n-1, e-0.0005

39
Q

what is the relative mass of a proton, neutron, electron?

A

p-1,n-1, e-0.0005 or 1/2000

40
Q

what is the relative charge of a proton, neutron, electron?

A

p- +1,n- 0, e- -1

41
Q

what makes up an atom?

A

protons, neutrons, electrons

42
Q

what charge does the nucleus have?

A

positive charge because of the electrons

43
Q

where is most of the mass in an atom?

A

concentrated in the nucleus

44
Q

where are electrons? what do they do?

A

move around in shells.

45
Q

what is atomic number?

A

proton number (but also electrons because no. electrons= no. protons)

46
Q

what is mass number?

A

total no. protons and neutrons

47
Q

what happens if an electron is removed or added to an atom?

A

it becomes an ion

48
Q

what is an atom?

A

The smallest particle of an element that contains electrons surrounding a nucleus that contains protons and neutrons.

49
Q

what is a molecule?

A

a group of two or more atoms that are chemically bonded together (these have no charge)

50
Q

what are isotopes?

A

different atoms (forms) of the same element that contain the same number of protons but a different number of neutrons

51
Q

what do you need to have to be an isotope?

A

different mass number, same proton number

52
Q

what is relative atomic mass?

A

Ar is the average mass of atoms of an element relative to the mass of an atom of carbon-12 (which is given a mass exactly of 12.
(it is also the average mass of all isotopes of an element. it has to allow for the relative mass and abundance for each isotope)

53
Q

how to find RAM?

A

((abundance x mass number) + (abundance x mass number of different isotope)) / total relative abundance

54
Q

what can be more easily separated - compounds or mixtures?

A

mixtures as there is no chemical bond between the different parts of a mixture. these can be separated out in different ways like distillation

55
Q

is a mixture pure? what is pure?

A

mixture - not pure
a substance is pure if it is completely made up of a single element or compound

56
Q

what difference does it make if something is pure or not

A

pure - specific melting/ boiling point
not pure - will melt or boil gradually over a range of temperatures

57
Q

what can filtration be used for?

A

can be used to separate an insoluble solid from a liquid

58
Q

how to carry out filtration?

A

if the product of a reaction is an insoluble solid, you can use filtration to separate it out from a liquid reaction mixture
it can be used in purification as well to get solid impurities out form a reaction mixture
all you need to do is put a folded filter paper into a cone shape into a funnel. slowly pour the mixture in. a solid residue will be left behind

59
Q

what can crystallisation be used for?

A

to separate a soluble solid (solute) from a solution

60
Q

how do you crystalise a product?

A
  1. pour the solution into an evaporating dish and gently heat the solution
  2. once some water has evaporated, or when you see crystals start to form (point of crystallisation), remove the dish from the heat and leave the solution to cool.
  3. the salt should start to form crystals as it becomes insoluble in the cold, highly concentrated solution
  4. filter the solutions, and leave them ina warm place to dry. you could also use a drying oven or desiccator (contains chemicals that remove water from the surroundings)
61
Q

what else can both filtration and crystallisation be used for?

A

can be used to make pure salt form rock salt

62
Q

how can you make pure salt from rock salt?

A
  1. grind the rock salt with a pestle and mortar
  2. dissolve in a beaker and stir (with water so salt dissolves)
  3. filter through filter paper in a funnel
  4. use crystallisation and evaporate in an evaporating dish (using a bunsen burner)
63
Q

what is rock salt? why is this useful?

A

a mixture of salt and sand. salt dissolves in water, but sand doesn’t so it can be separated

63
Q

what can simple distillation be used for?

A

used to separate out solutions or components form a solution

64
Q

what is a solution?

A

The mixture formed when a solute is dissolved in a solvent.

65
Q

how to use simple distillation? describe how you would go about it?

A
  1. heat the solution. the part of the solution that has the lowest boiling point starts to evaporate
  2. the vapour is then cooled, condenses (turns back into a liquid) and is collected
  3. the rest of the solution is left behind in the flask
  4. you can use it to get pure water from salt water
  5. you can only use simple distillation to separate things with very different boiling points
    - the set up of the experiment looks like a flask with the main liquid with a bung and thermometer.
    - then there is a glass tube that branches out of it to let the thing you are separating out to go into a beaker
66
Q

what is fractional distillation used for?

A

to separate a mixture of liquids

67
Q

name an example of when fractional distillation is used.

A

to separate crude oil

68
Q

how would you go about doing fractional distillation?

A
  1. put the cude oil substitute into a flask
  2. attach a column on top which is filled with glass rods (with a bund and thermometer at top). this column has a glass tube that branches out (which also letsd water in and out + where the fractions condense and allow liquid to be separated out into different conical flasks)
  3. do the lowest boiling point first and then increase ti after you have gotten your first fraction
  4. the liquids with higher boiling points might start evaporating but they wont get to the top because it is too cool so they will start ot condense and run down towards the flask
69
Q
A