Topic 3 - Chemical Changes Flashcards

1
Q

Aqueous Solutions

A

Something that has been dissolved in water

( can either be acid, alkaline or neutral )

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2
Q

PH scale

A

Mesures how acidic or alkaline something is
0 - 6 = Acid
7 = Neutral
8 - 14 = Alkaline

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3
Q

Indicators

A

Substances that change color depending on the PH

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4
Q

What are 3 common Universal Indicators?

A

Litmus, Methyl Orange and Phenolphthalein

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5
Q

What is the color range of Litmus in PH ?

A

Alkaline = blue
neutral = purple
Acidic = Red

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6
Q

What is the color range of methyl orange in PH?

A

Alkaline / = Yellow
Acid = Red

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7
Q

What is the color range of phenolphthalein in PH

A

Alkaline = Pink
Acid / Neutral = Colorless

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8
Q

Ion

A

An atom that has a net charge through loosing or gaining electrons

( metals always make a + ion)

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9
Q

Polyatomic Ions

A

Groups of atoms held together by covalent bonds, has a net charge.

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10
Q

What do acids do when in water? How does this cause their Ph?

A

They dissociate/ ionise - they form H+ ions in water. As the concentration of H+ ions increases, the Ph decreases

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11
Q

What is the formula for hydrochloric acid?

A

HCl

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12
Q

What is the formula for sulfuric acid?

A

H2SO4

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13
Q

What is the formula for nitric acid?

A

HNO3

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14
Q

What is the formula for sodium hydroxide

A

NaOH

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15
Q

What is the formula for Potassium hydroxide

A

KOH

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16
Q

What is the formula for Calcium hydroxide?

A

Ca(OH)2

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17
Q

How does Hydrochloric acid dissociate when in water?

A

HCL –> H+1 + Cl-4

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18
Q

How does Sulfuric acid dissociate when in water?

A

H2SO4 —-> H+2 + SO-2

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19
Q

How does nitric adis dissociate when in water?

A

HNO3 –> H+ + NO3 -

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20
Q

What do acids produce when dissociating in water?

A

Hydrogen ions

H+

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21
Q

What do alkalis produce when dissociating in water?

A

Hydroxide ions

OH-

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22
Q

What is Ph a mesure of ?

A

How many hydrogen ions are in a solution.
More H+ = Higher concentration = lower PH = More acidic
More hydroxide = more alkaline
hydrigen ions are equal to hydroxide ions = neutral PH

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23
Q

What is the Equation for concentration?

A

Con (g/dm3) = Amount dissolved / Volume of solution

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24
Q

what is the unit for concentration?

A

Grams per decimetre cubed or g/dm3

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25
Q

What is a dm3

A

cm3 times 1000

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26
Q

What difference is there between different PH?

A

x 10 or / 10
PH 6 x 10 = PH 7

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27
Q

Bases

A

substances that reacts with (neutralises) acids to form a salt and water only

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28
Q

What is the equation or bases and salts?

A

Metal oxide + acid —-> salt + water

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29
Q

Neutralisation

A

The chemical reaction in which a base is mixed with and acid to form a water and salt

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30
Q

How does an acid become neutal in neutralisation?

A

During neutalisation, hydrogen ions in the acid combine with oxide ions to form water. this removes the hydrogen and so the ph increases

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31
Q

How is a solution more acidic?

A

That solution will have a higher concentration of hydrogen ions
( as the concentration of H+ increases, the PH decreases)

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32
Q

What is a common base?

A

Metal Oxides ( they are basic/ alkaline)

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33
Q

What does acid strength tell you?

A

what proportion of the acid molecules ionise in water
more ionise = higher concentration of Hydrogen ions = lower PH

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34
Q

What are some strong acids?

A

Nitric, sulfuric, hydrochloric

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35
Q

What are some weak acids?

A

Carbonic, ethonic, boric

36
Q

What do strong acids do in water?

A

They almost completeky ionise, a large proportion of the acid molecules dissociate to release h + ions
this cannot be reversed

37
Q

What do weak acids do in water?

A

they do not fully ionise in solution, only a small proportion of the acid molecules dissociate to release H + ions
These dissociations can be reversed

38
Q

What does concentration mesure?

A

How much acid there is in a litre of water ( how watered down your acid is)

39
Q

What is an acid with a larger number of acid molecules compared to the volume of water called?

A

concentrated acid

40
Q

what is the opposite of concentrate?

A

dilute

41
Q

Why is extra base always added when prepping soluble salts?

A

to make sure all the acid is used up

42
Q

Why is the extra reactant/ base always filtered out?

A

so you are left with just salt and water so you can have pure crystals

43
Q

Why is the filtered solution in a soluble salts experiment alwats just salt and water?

A

through the base added to the acid in exess, then filtered out, we can make the solution fully neutalised, leaving only salt and water

44
Q

what is effervesence?

A

Bubbles

45
Q

metal + acid =

A

salt + hydrogen

46
Q

metal oxide/ hydroxide + acid =

A

salt + water

47
Q

how are soluble salts produced?

A

the reaction between an acid and an insoluble metal OXIDE

48
Q

how are insoluble salts produced

A

the reaction between an acid and a metal HYDROXIDE

49
Q

what is the ionic equation for neutralisation?

A

H+ + OH- = H20

50
Q

How do you test for hydrogen

A

The squeaky pop text
take a lit splint and hold it over the test tube, if it pops, there is hydrogen

51
Q

How to test dor carbon dioxide

A

Bubble it through limewater, it will turn the water cloudy

52
Q

how to test for oxygen?

A

Glowing splint test
but a just burnt out match into the test tube, it is re lit if there is oxygen

53
Q

How to test for chlorine

A

it turns litmus papar white

54
Q

What are spectator ions?

A

the ions that dont change in the reaction

55
Q

What are the spectator ions in
metal + acid -> salt + hydrogen?

A

the non H+ ions in the acid
e.g. Cl, N, S,O

56
Q

WHat do half equations show?

A

what happens to the electrons

57
Q

What happens in an oxidiation reaction?

A

a loss of electrons

58
Q

What is reduction reaction?

A

a gain of electrons

59
Q

What happens in electrolysis

A

The breaking down of a substance using electricity. An electric current is passed through an electrolyte, causing it to decompose

Oxidation or Reduction

60
Q

What is an electrolyte

A

a molten or dissolved ionic compound

61
Q

Cations

A

Positive ions

62
Q

Anions

A

negative ions

63
Q

ELECTOLYSIS

which Stick do the cations (+) move to?

A

The cathode (-)

They Gain electrons

REDUCED

64
Q

ELECTROLYSIS

which Stick do the anions (-) move to?

A

The anode

They loose electrons

OXIDISED

65
Q

What happens to the ions as they reach the anode/cathode?

A

As they gain/loose electrons they form uncharged substances and are dicharged from the electrolyte

66
Q

Why cant an ionic solid be electrolysed?

A

The Ions are in fixed positions and cannot move, therefore cannot conduct electricity

67
Q

What are metal ions?

+ or -

A

+

68
Q

What do positive metal ions do in electrolysis?

A

They are reduced to metal atoms at the cathode

69
Q

What do negative ions do in electrolysis?

A

Oxidised to atom or molecules at the anode

70
Q

What forms at the cathode when the electolysis is in SALT WATER

or aqueous solution

A

If there is gold, silver or copper that will be produced. IF not hydrogen

71
Q

What forms at the anode when the electolysis is in SALT WATER

or aqueous solution

A

if a halide is present the halogen will be produced
If not then its oxygen

72
Q

What metals are less reactive than hydrogen?

A

gold, copper, platinum, silver

73
Q

in order, what metals are more reactive than carbon?

A

K
Na
Ca
Mg
Al
C

74
Q

What metals are more reacitve than H but less reactive than C? in order.

A

Zn
Fe
H

75
Q

Metal carbonate + Acid ->

A

→ Salt + carbon dioxide + water

76
Q

What is an alkalai?

A

A base that is soluble in water
Ph of more than 7 as they form OH- ions in water

77
Q

WHat is the reaction between an acid and a base called?

A

Neutralisation

78
Q

Acid + Base =

A

Salt + Water

79
Q

What does the ionic equation for Neutralisation in Aqueous solution?

A

H+ + OH- = H20

80
Q

What do strong acids do in water?

A

They Ionise completely in water- A large proportion of the acid molecules dissociate to release H+ ions.

e.g Sulfuric, Hydrochloric, nitric

Ph 0-2

81
Q

what do weak acids do in water?

A

They dont fully ionise in solution - A small proportion of the acid molecules dissociate to release H+ ions.

e.g Ethanoic, citric, carbonic

Ph 2-6

82
Q

How do the reactions of Strong and weak acids differ in reversibility?

A

Ionisation of weak acids is reversible -Sets up an equilibrium, lies well to the leftnsince only a few of the cid releases H+ ions

83
Q

Acid + Metal oxide/Hydroxide =

A

Salt + Water

84
Q

Acid + Metal =

A

Salt + Hydrogen

85
Q

Acid + Metal Carbonate =

A

Salt + water + Carbon Dioxide

86
Q
A