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Chem > Paper 2 > Flashcards

Paper 2 Flashcards

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1
Q

What does a titration allow you to do

A

To find out the amount of acid needed to neutralise an alkali or vice versa

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2
Q

List the equipment needed for a titration

A

Pipette, pipette filler, burette, conical flask, indicator, acid, alkali (around 25cm3)

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3
Q

Steps of a titration

A

Add alkali using pipette and pipette filler to concical flask, and add two drops of indicator
Fill burette with acid below eye level
Add acid to alkali using burette, swirling conical flask, go slowly when colour change is about to be reached
Indicator changes colour when all alkali is neutralised (e.g. phenolphthalein is pink in alkali but colourless in acid)
Record volume of acid used to neutralise alkali

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4
Q

How can you make sure you get more reliable results of a titration

A

Repeat a few times making sure you get the same answer each time

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5
Q

How can you make soluble salts using an acid and an alkali

A

Perform titration adding alkali to acid, as well as indicator, then do it again without indicator to not contaminate the salt.
Evaporate some of the water and leave to crystalise
Filter off solid and dry it, you’ll be left with a pure, dry salt

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6
Q

How to convert from cm3 to dm3

A

Divide by 1000

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7
Q

What is metallic bonding

A

Electrostatic attraction between the nuclei of the positive ions and the electrons

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8
Q

Why can metals conduct electricity

A

Moving delocalised electrons

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9
Q

Why can metals conduct heat well

A

Electrons transfer energy quickly

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10
Q

Why are metals malleable

A

Layers of ions can slide over each other

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11
Q

What do iron copper and aluminium have in common

A

Density
Lustrous (shiny)
High melting point
High tensile strength (strong and hard to break)
Good conductors

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12
Q

Exclusive properties of iron

A

Malleable (gates and railings)
Corrodes easily
Used in steel

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13
Q

Exclusive properties of aluminium

A

Doesnt corrode easily
React quickly with oxygen to form a protective layer of aluminium oxide e.g. drinks can
Less dense (lighter) e.g. planes

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14
Q

Exclusive properties of copper

A

Good conductor of heat and electricity
Low resistance (efficient at transferring electricity) e.g. electrical components, underfloor heating

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15
Q

Why are alloys harder than pure metals

A

Because the ions cant slide over each other because the elements have different sized atoms and will distort the layers of pure metal atoms

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16
Q

Uses of low carbon steel

A

Easily shaped e.g. car bodies

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17
Q

Uses of high carbon steel

A

Very strong, inflexible, brittle e.g. bridges

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18
Q

Uses of stainless steel

A

Contains chromium and sometimes nickel, corrosion resistance and hard e.g cutlery

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19
Q

Example of other alloys

A

Bronze - copper and tin
Brass - copper and zinc

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20
Q

Formula for concentration

A

Concentration = moles/volume

21
Q

What is concentration measured in

A

Moles per dm3

22
Q

How do you convert from mol/dm3 to g/dm3

A

mass (g) = moles x RFM

23
Q

What is Avagadro’s law

A

One mole of any gas occupies 24dm3

24
Q

How do you convert the number of moles of any gas at room temp and pressure (RTP)

A

volume (dm3) = moles of gas x 24

25
Q

How do you calculate volumes in reaction if you know the masses

A

Write out balanced equation
Work out RFM of substance you know mass of
Calculate number of moles of substance
Look at ratio
Use vol = mol x 24 to find answer

26
Q

What is electrolysis

A

The breaking down of a substance using electricity

27
Q

What is an electrolyte

A

A molten or dissolved ionic compound

28
Q

What happens during electrolysis

A

An electric current is passed through an electrolyte causing it to decompose.

29
Q

OILRIG

A

Oxidation is Loss
Reduction is Gain

30
Q

Describe the movement of ions during electrolysis

A

The positive ions (cations) are attracted to the cathode (negative) (reduction as electrons are gained)
The negative (anions) are attracted to the anode (positive) (oxidation as electrons are lost)

31
Q

Why can molten ionic compounds be electrolysed

A

The ions can move freely

32
Q

How would you write a half equation that shows what happens at the cathode

A

Write down the reactant and the product
Balance equation
Write charges
Balance by adding electrons

33
Q

Why do covalent compounds not conduct electricity

A

Because the molecules are neutral and there are no charged particles

34
Q

Why can’t ionic compounds conduct electricity when solid

A

Because they are helt together in a lattice form and can’t move

35
Q

What does inert mean

A

Unreactive

36
Q

How would you investigate electrolysis using copper sulphate

A

Pour copper sulphate into beaker
Put two graphite rods in copper sulphate, attach electrode to negative terminal of DC supply, and other electrode to positive terminal
Fill two test tubes with copper sulphate and position a test tube over each electrode
Turn on power and observe what happens
Test any gas with glowing and lit splint

37
Q

How would you predict the products of electrolysis in a molten compound

A

Metals would be attracted to the cathode as they are positivey charged
Non-metals would attracted to the anode as they are negatively charged

38
Q

What element is formed when sulphate is attracted to the anode

A

Oxygen

39
Q

What is an electrochemical cell

A

A circuit made up of an anode, cathode, electroyte, power source and the wires that connect the two electrons

40
Q

What happens if there is an halogen present at the anode

A

Molecules of halogens will be formed, if there arent any present, oxygen will be formed

41
Q

What happens if hydrogen and metal ions are present

A

If the metal is more reactive thatn hydrogen, hydrogen gas will be produced, if not, a solid layer of the pure metal will be produced

42
Q

How do you prepare a sample of pure dry lead sulphate

A

Add 1 spatula of lead nitrate to test tube, and deionised water
Shake thoroughly so that its dissolved
Do same with 1 spatula of magnesium sulphate
Tip both solutions into small beaker and stir
Filter the precipitate using filter paper and funnel and conical flask
Rinse filter paper with deionised water to make sure all the soluble magnesium nitrate has been washed away

43
Q

What is solubility

A

The amount of substance that will dissolve in a given volume of solvent (measured in grams per 100 grams of solvent)

44
Q

How would you investigate how the solubility of a solid is affected by temperature

A

Add excess ammonium chloride to water in boiling tube
Stir and place in water bath set to 25 degrees
After 5 mins, check that excess solid has sunk to bottom of tube
Check that its at 25 degrees
Weigh empty evaporating basin
Pour some solution into basin and reweigh
Heat gently using bunsen to evaporate all water
Reweigh
Repeat steps with water at different temps

45
Q

Solubility formula

A

Solubility = mass of solid (g) / mass of water removed

46
Q

Why do covalent compounds not conduct electricity

A

Covalent substances share pairs of electrons so they dont contain ions and they dont have any charged particles that are free to move and conduct electricity

47
Q

Things to remember for electrolysis and balanced half equations

A
  1. In solutions, there are also H+ ions and OH- from the water
  2. At the cathode, hydrogen gas is produced if the metal is more reactive than hydrogen e.g. sodium
  3. If the metal is less reactive than hydrogen e.g. copper, then a solid layer of pure metal will be produced
  4. At the anode, if halide ions arent present then oxygen will be formed
48
Q

Explain why alkali metals become more reactive as their atomic number increases

A

The outer most electron is the furthest from the nucleus as you go down, which means the attraction between the atom and nucleus is weaker, the atoms get bigger as you go down group 1, meaning that the outer electron is more easily lost

49
Q
A

Chem (9 decks)

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