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Chemistry > States of matter and mixtures > Flashcards

States of matter and mixtures Flashcards

1
Q

What is a solid?

A
  • Particles are regularly arranged in a lattice with strong forces of attraction keeping a definite shape and volume
  • and can only vibrate in a fixed position
  • particles don’t have much energy
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2
Q

What is a liquid?

A
  • there is some force of attraction between particles as they are free to move but tend to stick together
  • don’t keep a definite shape and will flow whilst keeping the same volume
  • more energy than solid states and particles are constantly moving with random motion (the hotter they get the more they move)
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3
Q

What is a gas?

A
  • next to no force of attraction between particles so are free to travel in straight lines only interacting when they collide
  • don’t keep definite shape or volume but exert pressure
  • more energy than both liquids and solids
  • move constantly with random motion
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4
Q

How does a solid melt into a liquid?

A
  • As it is heated it’s particles gain mor energy causing them to vibrate more which weakens their forces
  • this makes the solid expand
  • at certain temperatures, the particles have enough energy to break free from their position turning into a liquid
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5
Q

How does a liquid evaporate into a gas?

A
  • as it is heated the particles gain more energy making the particles move faster making their bonds weaken or break
  • at a certain temperature the particles have enough energy to break their bonds and the liquid evaporates into a gas
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6
Q

What are all the changes in state?

A 
-Solid  to liquid = melting
Solid to gas = subliming 
-liquid  to gas =evaporating 
Liquid to solid = freezing 
-gas to liquid -condensing
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7
Q

What are harder to reverse chemical or physical changes?

A

Chemical as often new substances are formed

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8
Q

What is a pure substance?

A

Something made up of a single element or compound

-if there is more than one element or compound present it is a mixture

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9
Q

What are the stages of testing for purity?

A
  • if a substance is a mixture then it will melt gradually over a range of temperature as it doesn’t have a uniformed composition rather than having a sharp melting point like a pure substance
  • through using a melting point apparatus you can measure the exact temperature something melts at to see if it pure
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10
Q

What does homogeneous mean?

A

The same throughout (pure)

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11
Q

What does heterogeneous mean?

A

Different throughout (impure)

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12
Q

What is distillation?

A

A process used to separate a liquid from a solution

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13
Q

What are stages 1,2 and 3 of simple distillation?

A
  • pour your sample of inky water into the distillation flask
  • set in the apparatus using a thermometer, distillation flask, condenser, delivery tube, test tube and beaker of Iced water
  • fill the beaker with icy water to condense the water vapour back into a liquid
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14
Q

What are stages 4, 5 and 6 of simple distillation?

A
  • Gradually heat the distillation flask on a half roaring flame causing the water to evaporate leaving the ink in the flask
  • the water vapour passes down the delivery tube into the test tube where it cools and condenses back in a liquid
  • this leaves the pure water and ink separate
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15
Q

What are some problems with simple distillation?

A

It can only be used to separate things with very different boiling points not similar ones

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16
Q

What us one hazard in Simone distillation and one way of preventing risk?

A
  • the distillation flask is glass and might smash causing broken glass and a hot mixture to be spilt
  • so use a clamp stand to hold it in place
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17
Q

What is fractional distillation?

A

A more complex form of distillation where you can separate things with similar boiling points

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18
Q

What are stages 1,2 and 3 of fractional distillation in a lab ?

A
  • put your mixture in a flask and attach a fractionating column and condenser above the flask
  • gradually heat the flask and the different liquids will have different boiling points so will evaporate at different times
  • the liquid with the lowest boiling point will evaporate first and go to the top of the column
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19
Q

What are stages 4 and 5 of fractional distillation in a lab?

A
  • Liquids with higher boiling points may also start to evaporate but the column is taller towards the top so they will only get part of the way up before condensing and running back into the flask
  • when the first liquid has been collected by aligning the matching test tube with the end of condenser raise the temperature until the next one reaches the top and condenses our if the column
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20
Q

What is a solute?

A

A solid that dissolves

21
Q

What is a solvent?

A

The liquid that dissolves a solid

22
Q

What is filtration?

A

The separation of insoluble solids from liquids

23
Q

What is crystallisation?

A

The separating of Soluble solids from liquids

24
Q

What are the stages of filtration?

A
  • place some filter paper into a funnel and pour your mixture into it
  • the liquid part of the mixture runs through the paper leaving behind a solid residue
25
Q

What are stages 1 and 2 of crystallisation?

A
  • pour the solution into an evaporating disk and gently heat the solution, some of the water will evaporate so the solution will be more concentrated
  • once some of the water has evaporated or when crystals start to for, remove the dish from the heat and leave the solution to cool
26
Q

What are stages 3 and 4 of crystallisation?

A
  • the salt should start to form crystals as it becomes insoluble in the cold, highly concentrated solution
  • filter the crystals out of the solution and leave in warmth to dry
27
Q

What is chromatography?

A

A cheap and easy method used to separate a mixture of Soluble substances and identify them
It works as different solutes dissolves with different success in different solvents

28
Q

What is a mobile stage in chromatography?

A

Where the molecules can more (either a liquid or gas)

-the water, the more Soluble the compound is the faster the mobile stage will carry up the stationary phase

29
Q

What is the stationary phase in chromatography?

A

Where the molecules can’t more (usually a solid)

-the chromatography paper

30
Q

What are some risks to manage during crystallisation and filtration?

A
  • don’t leave the Bunsen burner unattended and heat slowly
  • if glass breaks, immediately clear up with dustpan and birth
  • wear goggles to avoid getting chemicals in your eyes
31
Q

What are stages 1 and 2 of chromatography?

A
  • draw a line near the bottom of the paper in pencil (as pencil insoluble so when interfere with the ink and move with the solvent) and draw a spot of the compound (ink) on the line
  • put some if the solvent into the beaker and place the bottom of the paper in the beaker (make sure the solvent is below the pencil line so the water dissolves up the paper rather than the inks into the water)
32
Q

What are stage 3 and 4 of chromatography?

A
  • put a watch glass on top of the beaker to prevent part of the solvent evaporating away
  • the solvent will start moving up the paper, when the chemicals in each dye dissolve in the solvent they will move up the paper too but at different points as they have varying solubility
33
Q

What are stages 5 and 6 of chromatography?

A
  • you will lend up seeing different chemicals in the sample separate out forming spots at different points on the paper
  • remove the paper from the beaker before the solvent reaches the top(the solvent should have travelled further than the inks) and mark the distance the solvent has moved in pencil (this is the solvent front)
34
Q

What is the RF value?

A

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

35
Q

What is the equation for the RF value?

A

RF value = distance travelled by the solute / divided by distance travelled by the solvent

36
Q

How do you measure the distance travelled by the solute?

A

Measure distance from the bassinet to the centre of the spot

37
Q

What two separation techniques could you carry out to analyse the composition of dyes in ink?

A
  • first, simple distillation to remove water

- then, paper chromatography go see the dyes that the ink is composed of

38
Q

What is surface water?

A

Water from lakes, rivers and reservoirs (start to dry out during summer)

39
Q

What is ground water?

A

Water from aquifers (rocks that trap water underground)

40
Q

What is waste water?

A

Water that has been contaminated by human processes

41
Q

What is stage 1 of purifying water in water treatment plants?

A

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

42
Q

What is stage 2 of purifying water in water treatment plants?

A

Sedimentation - iron sulphate or aluminium sulphate is added to the water which makes fine particles clump together and settle at the bottom

43
Q

What is stage 3 of purifying water in water treatment plants?

A

Chlorination - chlorine gas is bubbles through to kill harmful bacteria and other microbes

44
Q

What is potable water?

A

Water made by distilling sea water

45
Q

Why might chemists use deionised water?

A
  • as normal tap water as harmful ions in such as copper and iron
  • however, in an experiment, these small presences of ions could interfere with the reactions, falsifying your results
46
Q

Advantages of 2D

A
  • Simple
  • good at showing what atoms and how they are connected
  • don’t show the shape of substances or size of atoms
47
Q

Dot and cross diagrams

A
  • useful for showing how molecules are formed and were electrons in bonds come from
  • don’t show the arrangement of atoms
48
Q

3D models

A
  • show arrangement of ions

- only show outer layer of a substance

Chemistry (12 decks)

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