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Chemistry > C2.1 > Flashcards

C2.1 Flashcards

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1
Q

What is relative atomic mass?

A

The mean mass of an atom of an element compared to 1/12 the mass of a carbon-12 atom

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2
Q

If there are atoms in a bracket with a subscript number next to it, what does that mean?

A

Every atom in that bracket should be multiplied by that number

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3
Q

What is relative formula mass?

A

The mean mass of a unit of a substance compared to 1/12 the mass of a carbon 12 atom

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4
Q

What is the rfm of water?

A

18

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5
Q

What is empirical formula?

A

The simplest whole number ratio of atoms in each element

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6
Q

How can you use rfm to balance equations?

A

The total rfm on both sides of the equation can be altered and checked to be equal

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7
Q

What is chemical purity?

A

When a substance only has one sort of thing or atom in it

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8
Q

What is an example of a useful mixture?

A

Water
Alloys
A lot of stuff

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9
Q

How can you determine whether a solid substance is pure with a bunsen burner?

A

Heat it up, and if it is pure then it will stay at the same temperature while melting but if it is impure it melts over a range of temperatures

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10
Q

Pure Substance X melts at 500 degrees celcius
Pure Substance Y melts at 450 degrees celcius
If impure substance Z melts at 510 degrees celcius,what conclusions could you make about it?

A

It is neither X nor Y, impure substances never melt higher than the pure version

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11
Q

How does filtration work?

A

It separates an insoluble substance from a solvent,as the solvent can pass through microscopic holes in the filter paper

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12
Q

What is the remains of filtration called

A

Residue

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13
Q

How does crystallisation work?

A

You heat a solution slowly,so that the solute gets left behind in regularly shaped crystals
You can filter them and dry them in an oven

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14
Q

How does simple distillation work?

A

If the solvent has a lower boiling point,you can heat it up so it evaporates,then passes through a condenser where cold water condenses it and you get pure solvent.

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15
Q

How does fractional distillation work?

A

It separates 2 or more substances from a mixture in liquid state.
It has a fractionating column
Where vapours condense and heat it up
This means that 2 gases will be separated as one condenses

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16
Q

Why would you heat ethanol electrically?

A

Ethanol is flammable so a naked flame could cause fire

17
Q

How does chromatography work?

A

It separates a mixture into its different substances
It relies on a stationary phase and mobile phase
The distance a spot travels depends on how well it bonds with each phase

18
Q

What is the stationary and mobile phase in paper chromatography?

A

Absorbent paper

Water (most likely)

19
Q

What is the stationary and mobile phase in thin layer chromatography?

A

Silica or alumina powder on a glass/plastic plate (tlc plate)
A solvent,probably not water

20
Q

What is the stationary and mobile phase in gas chromatography?

A

Silica or alumina powder packed in a metal column

Unreactive carrier gas

21
Q

How do you work out retention factor?

A

Distance travelled by substance / distance travelled by solvent

No units

22
Q

How does a chromatogram show a substance?

A

A peak in the graph

23
Q

What things do you need to be careful about when doing paper chromatography?

A

Draw the line in pencil
Draw the line and dot above the solvent
Keep the paper in place

24
Q

If a spot in chromatography doesnt move,what does it suggest?

A

It is insoluble in the used solvent

25
Q

How can you tell if food has a certain food colouring?

A

Do chromatography and if the 2 have a spot of the same Rf then the food has that colouring

26
Q

How do you separate crude oil?

A

By fractional distillation

27
Q

What 2 methods can you use to separate Salt and sand from water

A

First filtration

Then crystallisation

Chemistry (5 decks)

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