Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Chemistry > C4 Chemical Changes > Flashcards

C4 Chemical Changes Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Chemistry flashcards Periodic Table flashcards Chemistry 101 flashcards Organic Chemistry 101 flashcards
1
Q

Examples of pH’s

A 
pH 0-1 stomach acid
2 - vinegar or lemon juice 
4 acid rain 
6 normal rain 
8 washing up liquid 
10 pancreatic juice 
11 bleach
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is an indicator

A

Dye that changes colour depending on whether it’s above or below a certain pH
Wide range indicators have many dyes - gradually change

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

What is an acid

A

A substance that forms an aqueous solution with a pH less than 7

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

What’s a base

A

Substance with pH greater than 7

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

Chemical reaction for neutralisation

A

Acid + base -> salt + water

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

What happens when an acid neutralises a base

A

All products are neutral

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

What do acids produce in water

A

Produce protons - they ionise in aqueous solution and produce hydrogen ions
H+ ion is a proton

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

What’s a strong acid

A

Strong acids ionise completely in water - acid particles dissociate to release H+ ions (sulphuric, hydrochloric and nitric

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

What are weak acids

A 
Weak acids (ethnicm citric and carbonic) don’t fully ionise in water - only small proportion dissociates to form H+ ions 
Ionisation of a weak acid is a reversible reaction - equilibrium between undissociated and dissociated acid. As there’s only a few H+ ions, equilibrium lies left
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why are strong acids more reactive

A

As the concentration of H+ ions is higher, rate of reaction is quicker

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

What is pH a measure of

A

Measure of concentration of H+ ions
Every decrease of pH 1 - concentration of H+ ions increase by factor of 10
pH 4 has 10x concentration of H+ ions than pH 5
Decrease by 2 - H+ increase by factor of 100

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

What is acid strength

A

Tells you what proportion of acid molecules ionise in water

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

What does concentration measure of acid

A

How much acid there is in a certain volume of water

pH decreases with increasing concentration no matter the strength

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

What are metal oxides and hydroxides

A

They’re bases that sometimes dissolve in water and these soluble compounds are alkalis

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

Chemical Reaction for acids and metal oxides or acids and hydroxides

A

Acid + metal oxide -> salt + water

Acid + hydroxide -> salt + water

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

What does the salt produced depend on

A

Depends on acid and metal ion
E.g
Hydrochloric acid + copper oxide -> copper chloride + water

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

Acid and what produces CO2

A

Acid and metal carbonates produce CO2

Metal carbonates are also bases

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

Chemical reaction for acids and metal carbonates

A

Acid + metal carbonates -> salt + water + carbon dioxide
E.g
Sulphuric acid + calcium carbonate -> sulphuric carbonate + water + carbon dioxide

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

What can you make soluble salts with

A

Insoluble bases -> need to pick right acid and insoluble base - like insoluble metal oxide, hydroxide or carbonate
Warm dilute acid
Add insoluble base bit by bit until no more reacts - neutralised = solid sinks
Filter excess solid
Gently heat with water + let cool- salt crystals should form - filtered from solution and dried - crystallisation

20
Q

What is reactivity based off of

A

How easily an atom looses electrons and forms ions

Higher up in reactivity series = more easily they form positive ions

21
Q

List the reactivity series from most to least

A

Potassium, sodium , lithium, calcium, magnesium, carbon, zinc, iron, hydrogen, copper

22
Q

Metals also react with water - chemical reaction

A

Metal + water -> metal hydroxide + hydrogen

23
Q

Speed of reaction is indicated by rate at which…

A

Bubbles of hydrogen are given off

More reactive metal = faster reaction

24
Q

Lots of metals react with oxygen to form…

A

Oxides through oxidation.

25
Q

What are Oxides often

A

Often ores that metals need to be extracted from

26
Q

What’s a reduction reaction

A

Separate metal from oxide

27
Q

Formation of metal ore

A

Oxidation = gain of oxygen

28
Q

Extraction of metal

A

Reduction = loss of oxygen

29
Q

Some metals can be extracted by….

A

Reduction with carbon

Some metals extracted from ores chemically by reduction using carbon

30
Q

What happens during reduction using carbon

A

Ore is reduced as oxygen is removed from it, and carbon is oxidised
E.g Iron(III)Oxide + Carbon -> iron + carbon dioxide

31
Q

How can metals higher than carbon be extracted

A

Extracted with electrolysis

32
Q

How can metals below carbon be extracted

A

Reduction by carbon - as carbon can only take away oxygen from metals less reactive than itself > displacement

33
Q

Why is gold mined in its elemental form

A

Some metals are so unreactive so they are in earth as the metal itself

34
Q

What’s a redox reaction

A

If electrons are transferred, it’s a redox reaction

35
Q

What is OIL RIG

A

oxidation is loss (of electrons)
Reduction is gain (of electrons)

Oxidation and reduction also used in terms of oxygen

36
Q

REduction and OXidation Happen…

A

At the same time > RED-OX

37
Q

Displacement reactions are…

A

Redox reactions

38
Q

What do displacement reactions involve

A

Involve one metal kicking the other out - > more reactive metal will displace the less reactive metal from its compound

E.g iron + copper Sulfate -> iron Sulfate + copper
Iron looses 2 electrons - oxidised
Copper gains two to become Copper atom - reduced

39
Q

What are ionic equations

A

Show useful bits of reactions

40
Q

What’s in an ionic equation

A

Contains only the particles that react are shown

E.g the displacement but not the stuff that doesn’t change

41
Q

What is electrolysis

A

Splitting up of electricity

42
Q

What happens during electrolysis

A

An electric current is passed through an electrolyte
Ions move towards electrodes where they react and the compound decomposes
Positive ions in electrolyte will move toward the cathode (-ve electrode) and gain electrons
Negative ions will move toward anode (+ve electrode) and lose electrons
Creates flow of charge through electrolyte as ions travel to electrodes
As ions gain/lose electrons they form uncharged elements and are discharged from the electrolyte

43
Q

What’s an electrolyte

A

Liquid of solution which can conduct electricity

44
Q

What’s an electrode

A

Solid that conducts electricity and is submerged in electrolyte

45
Q

What does electrolysis of molten ionic solids form

A

Forms elements
An ionic solid can’t be electrolysed because ions in fixed positions and can’t move
Molten ionic compounds can be electrolysed as ions can move freely and conduct electricity
Molten ionic liquid e.g lead bromide are always broken up into their elements
Positive metal ions reduce to element at cathode
Negative non-metal ions oxidised to element at anode

46
Q

How can metals be extracted from ores with electrolysis

A

Method is very expensive as lots of energy required to melt ore and produce required current
1. Aluminium extracted from bauxite by electrolysis
2. Aluminium oxide has high melting point - mixed with cryolite to lower point
3. Molten mixture contains free ions - conductor
4. Positive Al3+ Ions attracted to negative electrode where they pick up 3 electrons and turn into neutral aluminium atoms - sink to bottom of tank
5. Negative O2- ions attracted to anode and loses 2 electrons -> neutral oxygen atoms combine to form O2 molecules
Aluminium -> Aluminium + oxygen oxide
At cathode Al3+ + 3e- —> Al
At anode 2O2- —> O2 + 4e-

47
Q

What happens during electrolysis of aqueous solutions

A

In aqueous solutions, there is H+ and OH- ions from water

At cathode if H+ ions present > hydrogen gas produced if the metal forms an elemental metal that is more reactive than hydrogen
If metal ions form elemental metal that is less reactive than hydrogen -> solid layer of pure metal produced

At anode if OH- and halide ions(Cl-, Br-, I-) present, molecules of chlorine, bromine or iodine are formed.
No halide ions - OH- ions discharged and oxygen formed
Examples on C4 loose sheet

Chemistry (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions