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Chemistry. > C4 chemical changes. > Flashcards

C4 chemical changes. Flashcards

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1
Q

what are acids?

A

contain hydrogen ions in aqueous solutions.

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2
Q

what are alkalis?

A

aqueous solutions of alkalis contain hydroxide ions.

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3
Q

what are strong acids?

A

completely ionised in aqueous solutions.

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4
Q

what are weak acids?

A

only partially ionised in aqueous solutions.

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5
Q

what is a hydrogen ion concentration?

A

as the pH decreases by one unit the hydrogen ion concentration increases by a factor of 10.

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6
Q

what are soluble salts?

A

can be made from reacting acids with solid insoluble substances.

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7
Q

what is production of soluble salts?

A

add the solid to the acid until no more dissolves. filter off excess solid and then crystalise to produce solid salts.

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8
Q

what does the process of of electrolysis mean?

A

when an ionic compound is melted or dissolved in water, the ions are free to move. these are then able to conduct electricity and are called electrolytes. passing an electric current through electrolytes causes the ions to move towards the electrodes.

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9
Q

what is an electrode?

A

the positive electrode is called the anode. the negative electrode is called the cathode.

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10
Q

where do the ions go electrolysis?

A

cations are positive ions and they move to the negative cathode. anions are negative ions and they move to the positive anode.

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11
Q

(H) what are titrations?

A

used to work out the precise volumes of acids and alkali solutions that react with each other.

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12
Q

how can metals be extracted from molten compounds?

A

using electrolysis.

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13
Q

when is electrolysis used to extract metal from molten compounds?

A

metal is too reactive to be extracted by reduction with carbon.

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14
Q

why is extracting metals using electrolysis expensive?

A

large amounts of energy needed to produce the electrical current.

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15
Q

what does aluminium extraction use and why? what has to be replaced regularly and why?

A

cryolite to lower the melting point of aluminium oxide.
made of graphite which reacts with the oxygen to form carbon dioxide.

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16
Q

in neutralization reactions what does hydrogen ions react with to produce water?

A

hydroxide ions.

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17
Q

what happens at the negative electrode?

A

metals will be produced on the electrode if it is less reactive than hydrogen. hydrogen will be produced if the metal is more reactive than hydrogen.

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18
Q

what happens at the positive electrode?

A

oxygen is formed at positive electrode unless a halide ion is present then chloride, bromine or iodine is formed at that electrode.

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19
Q

what can a universal indicator or a pH probe be used for?

A

measure the acidity or alkalinity of a solution against the pH scale.

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20
Q

how to perform titrations?

A

1) use the pipette to add 25cm cubed of alkali to a conical flask and add a few drops of indicator.
2) fill the burette with acid and note the starting volume. slowly add the acid from the burette to the alkali in the conical flask, swirling to mix.
3) stop adding acid when the end point is reached (the appropriate colour change in the indicator happens.) note the final volume reading. repeat steps 1 to 3 until you get consistent readings.

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21
Q

what is a pipette used for?

A

fixed volumes only.

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22
Q

what is a burette used for?

A

variable volumes.

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23
Q

what do ionic half equations show?

A

what happens to each of the reactants during reactions.

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24
Q

what is the salt name for the acid: hydrochloric acid?

A

chloride.

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25
Q

what is the salt name for the acid: sulphuric acid?

A

sulphate.

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26
Q

what is the salt name for the acid: nitric acid?

A

nitrate.

27
Q

what is neutralisation?

A

acids can be neutralised by alkalis and bases.

28
Q

what type of base are alkalis and give an example?

A

soluble.
eg: metal hydroxide.

29
Q

what is a base and give an example?

A

substance that neutralises an acid.
eg: metal hydroxide or metal oxide.

30
Q

what do metals react with oxygen to form?

A

metal oxides.

31
Q

what is reduction?

A

oxygen is removed/ gain of electrons from a compound during a reaction.

32
Q

what is oxidation?

A

oxygen is gained by a compound during a reaction.

33
Q

what type of reaction are those between metals and acids and why?

A

redox. metal donates electrons to the hydrogen ions. displaces hydrogen as a gas while the metal ions are left in the solution.

34
Q

what is the generic equation for reactions with acids?

A

metal + acid → salt + hydrogen.

35
Q

how do you extract using carbon?

A

metals less reactive than carbon can be extracted from their oxides by reduction.

36
Q

what would you use extraction of metals and reduction on and how?

A

unreactive metals such as gold which are found in the earth as the metal itself. mined from the ground.

37
Q

how does this group react with water: group 1 metals?

A

reactions get more vigorous as you go down the group.

38
Q

how does this group react with acids: group 1 metals?

A

reactions get more vigorous as you go down the group.

39
Q

how does this group react with water: group 2 metals?

A

do not react with cold water.

40
Q

how does this group react with acids: group 2 metals?

A

observable reactions include fizzing and temperature increase.

41
Q

how does this group react with water: zinc, iron and copper?

A

do not react with water.

42
Q

how does this group react with acids: zinc, iron and copper?

A

zinc and iron react slowly with acid. copper does not react with acid.

43
Q

what do metals form when they react?

A

positive ions.

44
Q

what is the reactivity of metal related to?

A

tendency to form positive ions.

45
Q

what does the reactivity series do?

A

arranges metals in order of their reactivity.

46
Q

what is different about carbon and hydrogen in the reactivity series and why are they included?

A

non-metals but included.
can be used toe extract some metals front their ores depending on reactivity.

47
Q

what can a more reactive metal do to a less reactive metal from a compound?

A

displace.

48
Q

what is the most and least reactive metal in the reactivity series?

A

most: potassium.
least: platinum.

49
Q

what are metal ores?

A

if a metal can be extracted for profit from the compounds in a rock, rock is an ore.

50
Q

what is the reaction with oxygen like for: potassium, sodium, calcium, magnesium, aluminium, zinc, iron, nickel, tin?

A

burns in oxygen.

51
Q

what is the reaction with oxygen like for: lead, copper, mercury, silver?

A

tarnish (metal oxide formed on the surface) but do not burn.

52
Q

what is the reaction with oxygen like for: gold and platinum?

A

no reaction.

53
Q

what is the reaction with water like for: potassium, sodium, calcium and magnesium?

A

fizzes with cold water.

54
Q

what is the reaction with water like for: aluminium, zinc, iron, nickel, tin, lead, copper, mercury, silver, gold and platinum?

A

no reaction.

55
Q

what is the reaction with acid like for: potassium, sodium, calcium, magnesium, aluminium, zinc, iron, nickle, tin and lead?

A

fizzes.

56
Q

what is the reaction with acid like for: copper, mercury, silver, gold and platinum?

A

no reaction.

57
Q

sodium + oxygen →?

A

sodium oxide.

58
Q

iron + oxgyen →?

A

iron oxide.

59
Q

zinc + hydrochloric acid →?

A

zinc chloride + hydrogen.

60
Q

copper + sulfuric acid →?

A

no reaction.

61
Q

silver + water →?

A

no reaction.

62
Q

calcium + water →?

A

calcium hydroxide + hydrogen.

63
Q

aluminium +iron oxide →?

A

aluminium oxide + iron.

64
Q

calcium + sodium oxide →?

A

no reaction.

Chemistry. (66 decks)

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