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Chemistry > Topic 4: chemical changes > Flashcards

Topic 4: chemical changes Flashcards

1
Q

what is oxidation

A

what a substance gains oxygen

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2
Q

what is reduction

A

when a substance loses oxygen

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3
Q

describe the reactivity series of metals

A

the series shows the metals in order of their reactivity

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4
Q

list the reactivity series

A

potassium
sodium
lithium
calcium
magnesium
aluminium
carbon
zinc
iron
lead
hydrogen
copper
silver
gold

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5
Q

what is a displacement reaction

A

a reaction where a more reactive metal displaces a less reactive metal from a compound

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6
Q

how are unreactive metals found in earth

A

in their natural state

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7
Q

how can metals less reactive than carbon be exerted

A

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

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8
Q

how metals more reactive than carbon be extracted

A

by electrolysis

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9
Q

how is oxidation defined in terms of electron transfer

A

loss of electrons

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10
Q

how is reduction defined in terms of electron transfer

A

gain of electrons

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11
Q

general equation for a reaction between metals and acids

A

metal + acid = salt + hydrogen

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12
Q

which metals in the reactivity series will react with acid

A

those above hydrogen

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13
Q

general equation for neutralisation reaction

A

base + acid = salt + water

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14
Q

general equation for the reaction between metal carbonate and acid

A

metal carbonate + acid = salt + water + carbon dioxide

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15
Q

general equation for the reaction between metal oxides and acids

A

metal oxide + acid - a salt + water

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16
Q

what is a redox reaction

A

a reaction where both oxidation and reduction occurs

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17
Q

how is a soluble salt formed

A

react the excess with some insoluble chemical
filter off leftovers
crystallise the product

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18
Q

what acids and alkalis produce in aqueous solutions

A

acids produce hydrogen ions
alkalis produce hydroxide ions

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19
Q

what are bases

A

bases are compounds that neutralise acids

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20
Q

what do acids produce in aqueous solutions

A

acids produce hydrogen ions in aqueous solutions

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21
Q

what do alkalis produce in aqueous solutions

A

alkalis are soluble bases, producing hydroxide ions in aqueous solutions

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22
Q

what is a PH scale

A

the measure of acidity or alkalinity of a solution

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23
Q

what does PH 7 show

A

a neutral solution

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24
Q

what are strong acids on the ph scale

A

0,1,2,3

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25
Q

what are weaker acids on the ph scale

A

4,5,6

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26
Q

what is weaker alkalis on the ph scale

A

8,9,10

27
Q

what are strong alkaline of the ph scale

A

11,12,13,14

28
Q

what is a strong acid definition

A

strong acid is completely ionised in aqueous solution

29
Q

what is a weak acid

A

weak acid is only partially ionised in aqueous solutions

30
Q

what happens to ph as concentration of hydrogen atoms increase

A

the ph decreases

31
Q

what is a the difference between concentrated acids and diluted acids

A

concentrated acid has more moles of acid per unit volume than dilute

32
Q

is concentrated and dilute acids the same as strong and weak acids

A

no
concentration is not the same thing as strength

33
Q

what does it mean when someone refers to the strength off an acid

A

strength refers to whether the acid is completely ionised in water or only partially

34
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

35
Q

what is electrolysis

A

the passing of an electric current through ionic substances that are molten or in solution to break them down into elements; ions are discharged at electrodes to produce these

36
Q

what is an electrolyte

A

the liquid/solution which conducts electricity

37
Q

what is a cathode

A

a negative electrode

38
Q

what is an anode

A

a postive electrode

39
Q

what occurs at the cathode during electrolysis

A

reduction occurs

40
Q

what occurs at the anode during electrolysis

A

oxidation occurs

41
Q

in aqueous electrolysis, which element is discharged at the cathode

A

the less reactive element discharges at the cathode. hydrogen is produced unless there is a less reactive metals in which the metal is produced.

42
Q

oxygen is produced at the anode, unless what happens…

A

unless the solution contains halide ions in which case halogen molecules are produced

43
Q

how is aluminium manufactured?

A

aluminium is made through the electrolysis of aluminium oxide and cryolite

44
Q

why is producing aluminium so expensive

A

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

45
Q

why is cryolite used in the manufacturing of aluminium

A

it lowers the the melting point of aluminium oxide, reducing energy costs

46
Q

which metals do not react with acids

A

copper
silver
gold

47
Q

how can you identify an acid ad metal from a salt

A

the metal is the same as the metal in the salt, and the acid name matches the non-metal part of the salt

48
Q

name the acid used to make sodium chloride

A

hydrochloric acid

49
Q

name the acid used to make iron nitrate

A

nitric acid

50
Q

name the acid used to make iron nitrate

A

nitric acid

51
Q

name the acid used to make copper sulphate

A

sulphuric acid

52
Q

name the acid used to calcium carbonate

A

carbonic acid

53
Q

what was the chemical formula of hydrochorlic acid

A

HCL

54
Q

what is the chemical formula of nitric acid

A

HNO3

55
Q

what is the chemical formula of sulphuric acid

A

H2SO4

56
Q

what is the chemical formula of carbonic acid

A

H2CO3

57
Q

what are the three key steps in preparing a salt from an acid and a metal

A

add excess metal to acid until it stops fizzing. filter off unreacted metal. evaporate off some of the water and leave to cool and crystallise

58
Q

how can prepared salt be dried

A

by patting dry with filter paper

59
Q

how should a salt solution be heated

A

gently with a water bath

60
Q

when describing the preparation of a salt, how can you be specific to the exam question

A

by naming the acid and metal needed to make the salt

61
Q

when adding metal to acid in preparation of a salt, what is used to contain the reaction

A

a beaker

62
Q

what 3 other substances can be used to prepare a soluble salt other than a metal

A

metal oxide
metal hydroxide
metal carbonate

63
Q
A

Chemistry (10 decks)

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