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chemistry > states of matter and mixtures > Flashcards

states of matter and mixtures Flashcards

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1
Q

Facts about solids (forces, energy)

A

Strong forces in attraction
Particles in a fixed postion only vibrate, meaning they keep their shape

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2
Q

Facts about liquids (forces, energy)

A

Some forces of attraction - free to move past each other but they do tend to stick together
Don’t keep a definite shape
The liquid state it’s particles will have more energy than in the solid state
The particles are constantly moving with random motion

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3
Q

Facts about gases (forces, energy)

A

No force of attraction free to move
Don’t keep a definitive shape of volume and will always fill any container
The gas state its particles will have the most energy out of solids and liquids

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4
Q

What is solid into a liquid?

A

Melting

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5
Q

What is liquid into solid?

A

Freezing

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6
Q

What is liquid to gas?

A

Evaporating

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7
Q

What is gas into a liquid?

A

Condensing

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8
Q

What is solid to a gas?

A

Subliming

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9
Q

How does a solid turn into a gas (deep explain including liquids)

A

When is solid is heated it’s particles gain more energy
This makes the particles vibrate more which awakens the forces that holds the solid together
A certain temperature of the particles have enough energy to break free from their positions. The solid will turn into a liquid.
When the liquid is heated again, the particles will get even more energy
This makes the energy particles move faster which we and breaks the bond holding the liquid together
At a certain temperature, the particles have enough energy to break their bonds. The liquid will turn into a gas.

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10
Q

Chemical changes are ______ to reverse

A

Hard

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11
Q

If a substance is pure, what does this mean?

A

Made up of a single element or compound

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12
Q

If there is more than one compound or element present, what is it called?

A

Mixture

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13
Q

How to test for purity using melting points?

A

If a substance is a mixture, then it will melt gradually over a range of temperatures rather than having a sharp melting point like a pure substance
Impure substances will melt over a range of temperatures because they are effectively mixtures
To measure the melting point of a substance you can use melting point apparatus - piece of kit that allows you to heat up a small sample of a solid very slowly so you can observe and record the exact temperature that it melts at

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14
Q

What is simple distillation used for?

A

Seperating liquid out of a solution
(Eg pure water from sea water)

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15
Q

What are the two types of distillation?

A

Simple and fractional

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16
Q

How do you use simple distillation to get pure water out of sea water

A

Pollo sample of sea water into the distillation flask
Set up equipment needed
Connect the bottom end of the condenser to a cult tap using rubber tubing. Run Coldwater through the condenser to keep it cool.
Gradually heat the distillation flask the part of the solution that has the lowest boiling point will evaporate
The water vapour passes onto the condenser where it caused and condenses, which means turns back into a liquid then flows into the beaker where it is collected.
You will then end up with your liquid

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17
Q

What is fractional distillation used for?

A

Separate a mixture of liquids

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18
Q

How do we use fractional distillation of crude oil at a refinery?

A

Put your mixture in a flask attached of fractionating column and condenser above the flask
Gradually heat the flask the different liquids will have different boiling points so they will evaporate at different temperatures
The liquid with the low boiling point evaporates first. When the temperature on the thermometer matches the boiling point of this liquid, it will reach the top of the column.
Liquids with higher boiling points might also start to evaporate but the column is cooler towards the top, so they will only get part of the way up before condensing and running back down towards the flask.
When the first liquid has been collected, raise the temperature until the next one reaches the top.

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19
Q

Propenyl, methanol, and ethanol have boiling points of 97°C, 65°C and 78°C. A student uses fractional distillation to separate a mixture of these compounds. Which liquid will be collected in the second fraction and explain why?

A

Ethanol has the second lowest boiling point and will be collected once all the methanol has been distilled off and the temperature increases.

20
Q

What is filtration used for?

A

To separate an insoluble solid from a liquid

21
Q

How do we filter a solution?

A

Pop some filter paper into a funnel and pull your mixture into it the liquid part of the mixture runs through the paper leaving behind a solid residue.

22
Q

What is crystallisation used for?

A

Separate a soluble solid from a solution

23
Q

How do you crystallise a product?

A

Pull the solution into an evaporating dish and gently heat the solution. Some of the water will evaporate in the solution will get more concentrated.
Once some of the water has evaporated when you see crystals starts to form, remove the dish from the heat and leave the solution to cool.
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 them in a warm place to dry. You should also use a drying oven or a desiccator.

24
Q

Substance X is a liquid at room temperature temperature has a melting point of 5°C and I’m boiling point of 60°C. Substance Y solid at room temperature it has a melting point of 745°C and a boiling point of 1218°C. Substance Y dissolves completely in substance X. Suggest a purification method you could use to obtain a pure sample of substance X and a pure sample of substance Y.

A

You could obtain a pure sample from substance acts using simple distillation.
You could obtain a pure sample of substance Y using crystallisation.

25
Q

What are the two phases chromatography uses?

A

Mobile phase - molecules are moving
Stationary phase - molecules don’t move

26
Q

In paper chromatography, the mobile phases is what?

A

Solvent

27
Q

What is the stationary phase in paper chromatography?

A

Piece of filter paper

28
Q

How to perform paper chromatography?

A

Draw a line near the bottom of the paper this is the baseline (use a pencil) and put a spot of the mixture to be separated on the line
Put some of the solvent into beaker dip the bottom of the paper into the solvent
Put a watch glass on the top of the beaker to stop any solvent from evaporating away
The solvent will start to move up the paper when the chemicals in the mixture dissolve in the solvent they will move up the paper too.
You will see the different chemicals in the sample separate out, forming spots at different places on the paper
Remove the paper from the beaker before the solvent reaches the top

29
Q

Molecules with the highest solubility in the solvent will travel further or lower up the paper?

A

Further

30
Q

How do we calculate RF value?

A

Distance travelled by solute divided by distance travelled by solvent

31
Q

A spot on a chromatogram moved 6.3 cm from the baseline the solvent front moved 8.4 cm. Calculate the RF value

A

6.3÷8.4 equals 0.75

32
Q

How would we use simple distillation and chromatography to analyse the composition of ink?

A

A mixture of different dyes dissolved in a solvent. To solvent the in contains you could try doing a simple distillation. Simple distillation allows you to evaporate of the solvent and collect it. The thermometer in the distillation set up or read the boiling point of the solvent when it’s evaporating. You can use the boiling point of the solvent to try determine what it is. You could then carry out paper chromatography on the sample of the ink. This will separate out the different dyes in the ink. Then you would do the RF value.

33
Q

What is potable water?

A

Water that is fit to drink

34
Q

What is surface water?

A

From lakes, rivers and reservoirs

35
Q

What is ground water?

A

From aquifers (rocks that trap water underground)
70% of water supply come from ground water

36
Q

What is waste water?

A

From the water that’s been contaminated by human process
Treating waste water to make it potable is preferable to disposing of the water which can be polluting
How easy waste water is to treat depends on the level of contaminants in it

37
Q

How can water be purified?

A

Filtration, sedimentation, chlorination

38
Q

What is filtration in purifying water?

A

Wire mesh screen out large twigs and then gravel and sand beds filter out any other solid bits

39
Q

What is sedimentation in purifying water?

A

Iron sulphate or aluminium sulphate is added to the water which makes fine particles come together and settle at the bottom

40
Q

What is chlorination in purifying water?

A

Chlorine gases bubbled through to kill harmful bacteria and other microbes

41
Q

What is a disadvantage of distilling sea water?

A

Distillation needs loads of energy so it’s really expensive, especially if you’re trying to produce large quantities of freshwater

42
Q

Water in chemical analysis must be what

A

Pure

43
Q

What water should you use when experiments involve mixing or dissolving something in water?

A

Deionised water

44
Q

What is the ionised water?

A

Water that has iron ,such as calcium and iron, that are present in normal tapwater removed

45
Q

What happens if you use normal water in an experiment?

A

It can give you false results

chemistry (4 decks)

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