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Chemistry > C2 > Flashcards

C2 Flashcards

1
Q

What is the relative atomic mass of an atom?

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

What does the chemical formula tell you?

A

How many atoms of each element there are in a unit of substance

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3
Q

What is the relative formula mass?

A

The mean mass of a unit of substance compared to 1/12 the mass of a Carbon-12 arom

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4
Q

What is the empirical formula?

A

The simplest whole number ratio of each of the atoms of each element in a compound

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5
Q

What is a “pure” substance?

A

A substances that consists of just one element or compound

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6
Q

How can the melting point be used to determine purity of a substance?

A

The greater the difference between the measured melting point and it’s accepted melting point, the lower the purity is likely to be

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7
Q

How do you determine the melting point?

A

Heat the substance slowly
Stir the substance as it melts

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8
Q

What is a solute?

A

The substance that dissolves

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9
Q

What is the solvent?

A

The substance that the solute dissolves in (a liquid)

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10
Q

What is a solution?

A

When one substance dissolves in another

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11
Q

What happens when a substance dissolves?

A

Its particles Speer are and become completely mixed with the particles of the solvent

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12
Q

What does soluble mean?

A

If a substance is soluble, it means that the substance can dissolve in a solvent

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13
Q

What does insoluble mean?

A

The substance cannot dissolve in a solvent

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14
Q

What is residue (during filtration)?

A

The particles that stay behind in the filter paper

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15
Q

What is the filtrate?

A

The particles of a dissolved solute that are small enough to pass through the filter paper

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16
Q

How does crystallisation work?

A

When the solvent evaporates slowly leaving the solute behind -heat too strong and you get powder

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17
Q

What is the apparatus needed for crystallisation?

A

Bunsen burner
Beaker
Tripod
Gauze
Evaporating basin

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18
Q

What are the apparatus needed for filtration?

A

Filter paper
Funnel
Conical flask

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19
Q

What does simple distillation involve?

A

Separating a solvent from a solution

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20
Q

What does simple distillation rely on?

A

The solvent having a much lower boiling point that the solute

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21
Q

What happens during simple distillation?

A

Solution is heated
Solvent boils, solute does not
Solvent escapes from solution in gas state
Cooled and condensed back into a liquid by a condenser
Collected in a test tube

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22
Q

Why is simple distillation useful?

A

You can purify a solvent with it

23
Q

What is the apparatus needed for simple distillation?

A

Round bottom flask
Bung
Thermometer
Test tube
Condenser - cooling water above

24
Q

What is the purpose of fractional distillation?

A

To separate two or more substances in the liquid state

25
Q

What does fractional distillation rely on?

A

On each substance having a different boiling point

26
Q

What is the apparatus needed for fractional distillation?

A

Round bottom flask
Fractionating column
Thermometer
Condenser (cooling water in bottom)
A beaker

27
Q

How does the fractionating column improve separation of the mixture?

A

It has a large surface area on which the vapours can continually condense

28
Q

What is a stationary phase?

A

The substance that doesn’t move

29
Q

What is the mobile phase?

A

The substance that moves

30
Q

What is the stationary phase in paper chromatography?

A

Absorbent paper

31
Q

What is the mobile phase in paper chromatography?

A

Solvent in the liquid state such as water or propanone

32
Q

What is the stationary phase in TLC?

A

A thin layer of silica/alumina powder spread over a plate of glass or plastic

33
Q

What is the mobile phase in TLC?

A

A solvent in the liquid state, such as water or propanone (same as paper chromatography)

34
Q

What is the apparatus needed for TLC?

A

Lid
TLC plate
Tank
Solvent
Sample

35
Q

What is the stationary phase in gas chromatography?

A

Silica or alumina powder packed into a metal column

36
Q

What is the mobile phase in gas chromatography!

A

An unreactive carrier gas such as nitrogen that doesn’t react with the sample

37
Q

What is the formula for Rf value?

A

Distance travelled by substance
———————————————
Distance travelled by solvent

38
Q

What happens to the sample during gas chromatography?

A

It turns into a gas when injected and the carrier gas pushes it through the column - the components take different times to trawl dependent on how strongly they bond to the stationary phase

39
Q

How does the computer produce a chromatogram in gas chromatography?

A

A detector sends a signal to the computer as each component leaves the column

40
Q

What are the peaks plotted against in a chromatogram?

A

Travel time

41
Q

How would a substance travel UP the plate/paper further in chromatography?

A

If it forms STRONGER bonds with the MOBILE phase rather than the stationary phase

42
Q

Why might a substance NOT travel UP the plate/paper as much in chromatography?

A

If it forms STRONGER bonds with the STATIONARY phase rather than the mobile phase

43
Q

Why is TLC better than paper chromatography?

A

It’s faster
More sensitive so a smaller sample can be used
Larger range of stationary phases and solvents to choose from

44
Q

How would you separate soluble and insoluble substances?

A

Dissolving followed by filtration

45
Q

How you one separate a solute dissolved in a solvent (solution)?

A

Crystallisation to obtain solute
Distillation (simple) to obtain solvent

46
Q

How would one separate 2 or more substances in the liquid state?

A

Fractional distillation

47
Q

How would one separate coloured soluble substances?

A

Paper chromatography or TLC

48
Q

What are the physical properties of metal elements?

A

Shiny
High melting/boiling point
Solid at room temp
Malleable (when solid)
Ductile (when solid)
Good thermal and electrical conductors

49
Q

What are the physical properties for non-metals?

A

Dull
Low melting/boiling point
Half solid, half gas at room temp
Brittle
Non-ductile
Insulators

50
Q

What are the chemical properties of metals?

A

They lose electrons to form positive ions
Do not react with each other (mix to form alloys)

51
Q

What are the chemical properties of non-metals?

A

Gain electrons to form negative ions
React with each other to produce compounds

52
Q

What happens when a metal oxide is dissolved in water?

A

It produces an alkaline solution

53
Q

What happens if non-metal oxides are dissolved in water?

A

It produces an acidic solution

54
Q

What is an ion?

A

An electrically charged particle formed when an atom or group of atoms lose or gain electrons

Chemistry (8 decks)

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