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GCSE AQA COMBINED SCIENCE CHEM P1 > C4 CHEMICAL REACTIONS > Flashcards

C4 CHEMICAL REACTIONS Flashcards

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1
Q

oxidation/reduction?

A

oxidation = gains oxygen
reduction = loses oxygen

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2
Q

what is the reactivity series of metals? what are the trends in reactivity metals in order with acids/water

A

the series shows the metal in order of their reactivity

metals above H2 in the series react with acid to produce H2 . the more reactive the metal is , the quicker and more violent reaction with acid occurs.

metals below H2 in the series don’t react with acids.

not all metals above H2 react with water - mostly group 1 and group 2 metals. aluminium is the border case.

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3
Q

displacement reaction?

A

when a more reactive metal displaces a less reactive metal from a compound

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4
Q

how are unreactive metals found in Earth?

A

in their natural state

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5
Q

how can metals be less reactive than carbon be extracted

A

reduction with carbon
carbon displaces the metal in a metal oxide - gets oxidised to carbon oxides
metal from the metal oxide gets reduced to the pure metal

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6
Q

how are metals more reactive than carbon extracted

A

by electrolysis

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7
Q

oxidation and reduction in terms of electrons?

A

oxidation - loss of electron
reduction - gain of electron

Oxidation
Is
Loss
Reduction
Is
Gain

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8
Q

equation for metal and acid?

A

metal + acid –> salt + hydrogen

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9
Q

equation for metal oxide and acid

A

metal oxide + acid –> salt + water

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10
Q

equation for metal oxide and acid

A

metal oxide + acid –> salt + water

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11
Q

equation for metal hydroxide and acid

A

metal hydroxide + acid –> salt + water

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12
Q

equation for metal hydroxide and acid

A

metal hydroxide + acid –> salt + water

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13
Q

equation for metal carbonate and acid

A

metal carbonate + acid –> salt + water + carbon dioxide

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14
Q

equation for metal carbonate and acid

A

metal carbonate + acid –> salt + water + carbon dioxide

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15
Q

which metals in the reactivity series will react with acid?

A

those above hydrogen

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16
Q

general equation for neutralisation

A

base + acid –> salt + water

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17
Q

redox equation?

A

both oxidation and reduction occurs

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18
Q

base?

A

any substance that reacts with an acid to form a salt and water only.
compounds that neutralise acids

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19
Q

explain in terms of gain or loss of electrons which species have been oxidised and which species has been reduced when magnesium reacts with hydrochloric acid

A

magnesium has lost electrons and thus has been oxidised (Mg to Mg2+)
hydrogen in HCl has gained electrons and thus have been reduced (H+ to H2)

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20
Q

explain in terms of gain or loss of electrons which species have been oxidised and which species has been reduced when magnesium reacts with hydrochloric acid

A

magnesium has lost electrons and thus has been oxidised (Mg to Mg2+)
hydrogen in HCl has gained electrons and thus have been reduced (H+ to H2)

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21
Q

how is a soluble salt formed?

A

react to the excess acid with some insoluble chemical (e.g metal oxide)
filter off the leftovers
crystallise the product

22
Q

what do acids and alkalis produce in aqueous solution?

A

acid produces hydrogen ions
alkalis produce hydroxide ions

23
Q

what are acids?

A

produce hydrogen ions in aqueous solution

24
Q

what are alkalis?

A

soluble bases produce hydroxide ions in aqueous solution

25
Q

what is the pH scale?

A

the measure of acidity

26
Q

what does pH level of 7?

A

neutral solution

27
Q

state the general equation for neutralisation reaction in a short , ionic form

A

H+ + OH- —> H20

28
Q

strong acid?

A

completely ionised in aqueous solution

29
Q

weak acid?

A

partially ionised in aqueous solution

30
Q

what happens to PH level as concentration of H+ increases?

A

ph decreases

31
Q

what is concentrated acid? and what is a diluted solution? is this the same as a strong and weak acid?

A
  • has more moles of acid per unit volume than dilute (dilute refers to solutions of low concentrations)
  • it is not the same - concentration is not the strength of an acid.
  • strength refers to whether the acid is completely ionised in water (strong) or only partially ( weak)
32
Q

as the pH is decreased by one unit what change is seen in the hydrogen ion concentration?

A

increases by a factor of 10

33
Q

name the following salts? LiNO3 , K2CO3 , MgBr2 , BaSo4

A

lithium nitrate , potassium carbonate , magnesium bromide , barium sulfate

34
Q

electrolysis?

A

decomposition of an electrolyte by an electric current.

35
Q

electrolyte?

A

liquid/solution which conducts electricity

36
Q

cathode?

A

negative electrode

37
Q

anode?

A

positive electrode

38
Q

what occurs at the cathode and what occurs at the anode during electrolysis ?

A

reduction = cathode
oxidation = anode

39
Q

in aqueous electrolysis , which element is discharged at the cathode ? oxygen is produced at the anode unless what?

A

less reactive element discharges at the cathode. hydrogen is produced unless there is a less reactive metal , in which case the said metal is produced . oxygen is produced at the anode unless the solution contains halide ions in which case halogen molecules are produced

40
Q

how is aluminium manafactured?

A

made through electrolysis of aluminium oxide and cryoilte.

lots of energy is needed to produce the current in electrolysis which makes this process expensive

41
Q

half equation for the extraction of aluminium?

A

al3+ + 3e- –> Al ( cathode)
2 O2- –> O2 + 4e- (anode)

oxygen needs to react with C of the anode producing CO2

42
Q

why is cryolite used in manufacturing of aluminium?

A

lowers melting point = reduces energy costs

43
Q

half equation in electrolysis of the aqueous Na2SO4?

A

2H+ + 2e- –> H2 (cathode)
4OH- –> 2H2O + O2 + 4e- (anode)

44
Q

half equation in electrolysis of the molten and aqueous KCl?

A

K+ + e- –> K (cathode)
2Cl- —> Cl2 + 2e- (anode)

2H+ + 2e- –> H2 (cathode)
2Cl- —> Cl2 + 2e- (anode) respectively

45
Q

half equations in electrolysis of the aqueous CuBr2?

A

Cu2+ + 2e- –> Cu (cathode)
2Br- —> Br2 + 2e- (anode)

46
Q

REQUIRED PRACTICAL: how could you prepare a sample of pure , dry copper sulfate crystals from a sample of insoluble copper sulfate?

A

react sulfuric acid with excess copper oxide.
filter to remove the excess copper oxide
heat the solution to evaporate
turn off the heat and leave until all the water has evaporated
left with copper sulfate crystals.

47
Q

REQUIRED PRACTICAL: chemical equation for the reaction between CuO and H2SO4

A

CuO + H2SO4 —> CuSO4 + H2O

48
Q

REQUIRED PRACTICAL: safety precautions need to be considered when preparing a pure dry salt from insoluble compound

A

bunsen burner should not be turned off or put on the safety flame when not in use.
sulfuric acid corrosive so eye wear protection

49
Q

REQUIRED PRACTICAL: separate an insoluble product from a solution?

A

filtration:
filter paper placed in a funnel over a conical flask
pour mixture through the funnel.
insoluble product left on the filter paper

50
Q

REQUIRED PRACTICAL: separate soluble from solutions?

A

place the mixture in an evaporating dish
slowly heat the solution
the solvent evaporates and the solution becomes more concentrated so crystals will start to form.
keep heating the evaporating dish until you have dry crystals

51
Q

REQUIRED PRACTICAL: separate solid from a solution of the solid decomposes when heated?

A

crystallisation:
pour the solution into an evaporating dish and heat gently.
when the crystals form , remove the dish from the heat and leave to cool.
once cold, filter the crystals out of the solution and leave them in a warm place to dry.

GCSE AQA COMBINED SCIENCE CHEM P1 (5 decks)

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