3.4 - Atmosphere & acids Flashcards

1
Q

what four gases is air composed of

A

nitrogen
oxygen
argon
carbon dioxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

how much nitrogen is in air

A

78%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how much oxygen is in air

A

21%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how much argon is in air

A

0.96%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

how much carbon dioxide is in air

A

0.04%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

how do you measure the percentage of oxygen in air

A

by reacting it with another element - often a metal
the air gradually decreases in volume until all of the oxygen has been added to the metal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what element might you heat to measure the percentage of oxygen

A

copper to form copper oxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how do you calculate the percentage of O2 in air

A

decrease in volume / initial volume of air x 100 = (should be 21)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

why might the air in one of the percentage oxygen experiment not decrease by 21%

A
  • the metal wasn’t heated for long enough for all the oxygen to be reacted
  • there’s a leak in the apparatus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is element combustion

A

when an element reacts with oxygen to produce an oxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the word equation for element combustion

A

element + oxygen –> element oxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the oxide name of a metal

A

metal oxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what state is a metal oxide

A

solid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the oxide name of a non-metal

A

non-metal dioxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what state is a non-metal dioxide

A

gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what does magnesium combust to form

A

magnesium oxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the word equation for the combustion of magnesium

A

magnesium + oxygen –> magnesium oxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is the chemical equation for the combustion of magnesium

A

2Mg(s) + O2(g) –> 2MgO(s)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what are the observations of the combustion of magnesium

A

bright white light
white powder formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what does sulphur combust to form

A

sulphur dioxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is the word equation for the combustion of sulphur

A

sulphur + oxygen –> sulphur dioxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is the chemical equation for the combustion of sulphur

A

S(s) + O2(g) –> SO2(g)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is an observation of the combustion of sulphur

A

blue flame

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what does hydrogen combust to form

A

water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what is the word equation for the combustion of hydrogen

A

hydrogen + oxygen –> water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what is the chemical equation for the combustion of hydrogen

A

2H2(g) + O2(g) –> 2H2O(l)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what is an observation of the combustion of hydrogen

A

squeaky pop

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what is the ion formula of Iron(II)

A

Fe 2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what is the ion formula of Iron(III)

A

Fe 3+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what is the ion formula of Copper

A

Cu 2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what is the ion formula of Silver

A

Ag+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what is the ion formula of Zinc

A

Zn 2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

what is the ion formula of Lead

A

Pb 2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

what is the chemical test for oxygen

A

glowing splint - relights

because the oxygen allows the wood in the splint to combust more efficiently

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

what solutions do metal oxides form when dissolved in water

A

alkaline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

what solutions do non-metal dioxides form when dissolved in water

A

acidic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

how can you determine whether an unknown element is a metal or non-metal

A

1- combust it in oxygen
2- dissolve the oxide formed
3- check the pH of the solution with an indicator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

what is an acid

A

H+ donor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

what is a base

A

H+ acceptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

what is an alkali

A

OH- donor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

what does an acid, alkali or base describe

A

a solution in terms of ions

42
Q

what does acidic or alkaline describe

A

a solution in terms of pH

43
Q

what happens with acids in water

A

acids dissolve and then donates H+ ions into the water
this causes the solution to have a pH < 7 and for it to be acidic

44
Q

what happens with alkalis in water

A

alkalis dissolve and the donate OH- ions into the water
this causes the solution to have a pH > 7 and for it to be alkaline

45
Q

what happens to bases in water

A

bases dissolve and then accept H+ ions from the H2O molecules
but when a H2O molecule loses a H+ ion what’s leftover is an OH- ion
it’s the OH- ions that cause the solution to have a pH > 7 and for it to be alkaline

46
Q

what are important acids

A

hydrochloric acid
nitric acid
sulphuric acid
phosphoric acid
carbonic acid

47
Q

what is the formula of hydrochloric acid

A

HCl

48
Q

what is the formula of nitric acid

A

HNO3

49
Q

what is the formula of sulphuric acid

A

H2SO4

50
Q

what is the formula of phosphoric acid

A

H3PO4

51
Q

what is the formula of carbonic acid

A

H2CO3

52
Q

what are important alkalis

A

sodium hydroxide
potassium hydroxide
ammonium hydroxide
(all soluble metal ions)

53
Q

what is the formula of sodium hydroxide

A

NaOH

54
Q

what is the formula of potassium hydroxide

A

KOH

55
Q

what is the formula of ammonium hydroxide

A

NH4OH

56
Q

what are some important bases

A

ammonia
(all metal oxides)
(all metal hydroxides)

57
Q

what is the formula of ammonia

A

NH4

58
Q

what is a polyatomic ion

A

an ion that contains more than one atom

59
Q

what is the ion name of nitric acid

A

nitrate

60
Q

what is the ion formula of nitrate

A

NO3 -

61
Q

what is the ion name of sulphuric acid

A

sulphate

62
Q

what is the ion formula of sulphate

A

SO4 2-

63
Q

what is the ion name of phosphoric acid

A

phosphate

64
Q

what is the ion formula of phosphate

A

PO4 3-

65
Q

what is the ion name of carbonic acid

A

carbonate

66
Q

what is the ion formula of carbonate

A

CO3 2-

67
Q

what is the ion name of all alkalis

A

hydroxide

68
Q

what is the ion formula of all alkalis

A

OH -

69
Q

what is the ion name of ammonium hydroxide (alkali)

A

ammonium

70
Q

what is the ion formula for ammonium (alkali)

A

NH4 +

71
Q

what is it impotant to use when writing polyatomic ions in chemical formulae

A

brackets

72
Q

what would magnesium nitrate formula look like

A

Mg (NO3)2

73
Q

what do bases react with metals to form

A

salt and water

74
Q

what is the equation for acid and base reaction

A

acid + base –> salt + water

75
Q

what is the important observation in and acid + base reaction

A

the base disappears because it is used up in the reaction

if the salt is soluble, it dissolves into the water to form a salt solution

76
Q

what reaction is used to make salt crystals

A

acid + base reaction

77
Q

explain how to make salt crystals

A

1- add excess base into a hot acid (this makes the salt solution quickly and ensures all the acid is used up)
2- filter out excess base ( the salt solution is the filtrate and is collected in the evaporating basin)
3- heat the salt solution until crystals start to form around the edges (this saturates the solution so that crystals form more efficiently)
4- leave the salt solution to crystalise (evaporation of water allows crystals to form)

78
Q

soluble salt equation

A

acid(aq) + base(s)/ alkali(aq) –> salt (aq) + water(l)

79
Q

how do you make pure dry crystals of soluble salt

A

1- make the salt solution
a) insoluble base method
b) titration method

2- crystalise the salt

80
Q

when do you use the insoluble bases method

A

when making salts that do not contain Na+, K+ or NH4 + ions

81
Q

what is the acid usually in the insoluble base method

A

one of hydrochloric acid (HCl), sulfuric acid(H2SO4) or nitric acid (HNO3)

82
Q

what is a base usually in the insoluble base method

A

a solid metal oxide

83
Q

explain the insoluble base method

A

1- heat the acid (hot acid has more energy so it reacts faster with the base)
2- while stirring, add base until no more will dissolve (this guarantees the base is in excess so that we know all the acid has been used up)
3- filter out the excess base

84
Q

when do you use the titration method

A

Na+, K+ or NH4+ ions because their bases are all soluble so you wouldn’t be able to filter out the excess if you used the insoluble base method

85
Q

what is the acid usually in the titration method

A

one of hydrochloric acid (HCl), sulfuric acid (H2SO4) or nitric acid (HNO3)

86
Q

what is the alkali usually in the titration method

A

one of sodium hydroxide (NaOH), potassium hydroxide (KOH) or ammonium hydroxide (NH4OH)

87
Q

explain the titration method

A

1- perform a titration to measure the volumes of acid and alkali that neutralise each other
2- repeat the titration but
a) don’t put the indicator in
b) use the burette to add exactly the right volume for neutralisation

88
Q

what is crystalisation

A

once you’ve made a salt solution, you perform crystalisation to get pure, dry salt crystals
(done in the same way, regardless of which method you used to make the salt solution)

89
Q

explain crystalisation

A

1- heat the salt solution until crystals just start forming
(you can tell by looking at the edges, or by occasionally dipping in a glass rod - this causes the solution to become saturated)
2- allow the solution to cool in an evaporating basin for a few days - this lowers the solubility of the salt so that lots of salt crystals form
3- filter out the crystals - this removes them from excess salt solutions in the basin
4- dry the crystals by dabbing them with filter paper - this removes the last traces of the water from the crystals

90
Q

what do carbonates react with metals to form

A

a salt,water and carbon dioxide

91
Q

what is the acid and carbonate equation

A

acid + carbonate –> salt + water + carbon dioxide

92
Q

what are the two observations in an acid + carbonate reaction

A

the carbonate disappears - because it is used up in a reaction

there is fizzing - because a gas(carbon dioxide) is produced

93
Q

what is the chemical test for carbon dioxide

A

limewater turns cloudy

94
Q

what is a precipitate

A

an insoluble solid that forms inside a solution

95
Q

how does a precipitate form

A

the ions in the solution collide with each other, a precipitate forms and slowly sinks to the bottom

96
Q

how can you tell if a precipitate will form

A

by mixing the ions up and seeing if either of the resulting compounds is insoluble
if an insoluble compound is formed it will appear as a precipitate

97
Q

how do you make insoluble salts

A

by mixing solutions to make a precipitate
each solution should contain one of the ions needed to make it

98
Q

what are the ions called that aren’t involved in making the precipitate

A

spectator ions and they remain in the solution as leftovers

99
Q

what is an ionic equation

A

a simpler equation for the reaction just involving the precipitate

100
Q

explain how you separate the salt from the solution after it has been made by precipitation

A

1- filter out the salt precipitate - the residue is the salt we want to keep + the filtrate is the leftover solution
2- rinse the salt was water - this washed off traces of the leftover solution, it doesn’t dissolve the salt because it is insoluble
3- dry the salt by dabbing it with filter paper - this removes the last few traces of water, leaving us with a pure dry salt