Brainscape's Knowledge GenomeTM

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


See full index

Chemistry⚗️ > Unit2Topic3 - Different Types Of Chemical Reactions > Flashcards

Unit2Topic3 - Different Types Of Chemical Reactions Flashcards

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

Signs that a chemical reaction is taking place

A

(i) change in appearance (eg colour)
(ii) energy change (eg heat, light, sound, electricity)
(iii) formation of precipitate
(iv) production of gas

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

What is an exothermic reaction?

A

Gives out more energy than it takes in

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

What is an endothermic reaction?

A

Takes in more energy than it gives out

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

Types of exothermic reactions

A

Combustion of fuels
Neutralisation
Displacement

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

Combustion of fuels

A

Combustion is the reaction of a fuel with oxygen that produces at least one oxide and releases energy.

Burning is an example of combustion.

fuel + oxygen -> carbon dioxide + water + heat

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

Neutralisation

A

When an acid and an alkali react, the H+ and OH- ions form water. Water is neutral.

H+ (aq) + OH- (aq) -> H2O (l)

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

Displacement

A

A more reactive element will displace a less reactive element from its compound.

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

Types of endothermic reactions

A

Thermal decomposition
Cracking
Photosynthesis

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

Thermal decomposition

A

Thermal decomposition is the breaking down of a compound using heat.

Eg. CaCO3 (s) -> CaO (s) + CO2 (g)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Cracking

A

The reaction used to break large hydrocarbon molecules into smaller molecules.

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

Photosynthesis

A

Energy + carbon dioxide + water -> glucose + oxygen

Light + 6CO2 + 6H2O -> C6H12O6 + 6O2

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

Consider…
CH4 (g) + 2O2 (g) ->CO2 (g) + 2H2O (g)

fuel(methane) + oxygen -> carbon dioxide + water + energy

A

Burning methane is an exothermic reaction because the energy required to break the bonds of the reactants (methane and oxygen) is less than the energy released on forming the bonds of the products (carbon dioxide and water).

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

All chemical reactions involve bond breaking and bond forming processes:

A

Breaking bonds is an endothermic process.

Bond making is an exothermic process.

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

Metal carbonates thermally decompose to give …

A

A metal oxide and carbon dioxide

Eg. CuCO3 (s) -> CuO (s) + CO2 (g)

(CuCO3 is green, CuO is black, heat over arrow)

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

Thermal decomposition of limestone

A

When limestone (calcium carbonate) is heated strongly it breaks down to calcium oxide (quick lime) and carbon dioxide.

This can take place in a lime kiln.

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

Thermal decomposition of calcium carbonate equations

A

Calcium carbonate -> calcium oxide + carbon dioxide

(Two calcium things are white, oxide is basic)

CaCO3 (s) -> CaO (s) + CO2 (g)

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

Uses of limestone

A

Blast furnace

Neutralising acidic soil

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

Blast furnace

A

Limestone is added to blast furnace during extraction of iron from its ore.

The calcium carbonate thermally decomposes to form calcium oxide.

The calcium oxide combines with the acidic impurities, silicon dioxide (sand), thus removing them.

Calcium oxide + silicon dioxide -> calcium silicate (slag)

CaO + SiO2 -> CaSiO3

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

Uses of calcium oxide

A

Mixed with water to produce limewater
CaO + H2O -> Ca(OH)2

To make plaster

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

Advantages of limestone quarrying

A
  • provides jobs
  • boosts economy
  • provides raw material for use in blast furnace and neutralising soil
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Disadvantages of limestone quarrying

A
  • eye sore
  • ruins animals’ habitats
  • noise/dust pollution
  • increased traffic congestion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What has increased the concentration of CO2 and other greenhouse gases in our atmosphere?

A

Human activity such as burning fossil fuels

23
Q

Global warming

A

Many suggest these greenhouse gases form a blanket around the earth, trapping heat and causing the average temperature at the earth’s surface to rise.

24
Q

The effect of high concentrations of CO2 in the atmosphere

A

Current temperature of atmosphere = 14°C.

2.7 billion years ago temp = 70°C due to intense volcanic activity, releasing large quantities of CO2.

Over time CO2 levels decreased as bacteria and plants slowly turned CO2 into carbonates (CO32-), organic material and oxygen via photosynthesis.

During last 100 years the average temp has risen by 1°C.

This has been enough to cause flooding, drought and destruction of habitats.

25
Q

Wegener’s Theory

A

In 1912 Alfred Wegener proposed the theory of continental drift.

Originally, all our present continents were joined together in a single land mass. About 200 million years ago the land mass started to break up and form continents. These continents could move and drift apart.

Wegener couldn’t explain how or why they could move apart.

26
Q

Current theory of continental drift

A

Plate tectonics

Continents move due to convectional currents in the mantle.

27
Q

Where do earthquakes and volcanoes occur?

A

Around plate boundaries

28
Q

What causes an earth quake?

A

Caused by the stresses and strains when 2 continental plates slide past each other or one slides under another. As the plates slide past they might even bend. Forces are suddenly released which causes the ground to shake violently and breaks and cracks develop in the ground.

29
Q

What causes a volcano?

A

Caused by plates moving apart. This causes the earth’s crust to be stretched. In areas of weakness, the crust may crack and molten magma and gases can escape through the cracks, resulting in a volcano.

30
Q

What is the chemical formula for rust?

A

Iron (III) oxide

Fe2O3.xH2O

31
Q

How is rust formed?

A

Iron reacting with both oxygen and moisture at room temperature.

32
Q

How is rusting sped up?

A

By salt

33
Q

Methods used to prevent rusting

A 
Painting
Oiling
Plastic coating
Suitable metal coating/plating (including galvanising)
Sacrificial protection
34
Q

What is galvanising?

A

Galvanising is a process that bonds a layer of zinc metal onto the surface of steel.

35
Q

How does galvanising work?

A

Zinc reacts with air to form protective zinc oxide layer.

36
Q

What is the advantage of galvanising?

A

Even if the zinc coating gets scratched or damaged, the exposed steel still won’t rust as the zinc will react instead of the iron.

37
Q

What is sacrificial protection?

A

A more reactive metal, in good contact with a less reactive metal, will always react first, therefore protecting less reactive metal from corrosion.

38
Q

Example of sacrificial protection

A

Iron boats often have a lump of magnesium bolted to their hulls - the Mg turns to MgO rather than iron turning to rust.

39
Q

What is a redox reaction?

A

A reaction where oxidation and reduction take place together.

40
Q

Oxidation is…

A

(i) the addition of oxygen
(ii) the removal of hydrogen
(iii) the removal of electrons

…to/from a substance.

41
Q

Types of oxidation reactions

A

Combustion of fuels

Rusting

42
Q

Examples of oxidation reactions

A

Mg is a grey shiny metal. Burns with bright white light. Forms a white ash.

Sulfur is a yellow brittle solid. Burns with blue flame. Forms pungent gas sulfur dioxide.

43
Q

Reduction is…

A

(i) the removal of oxygen
(ii) gain of hydrogen
(iii) gain of electrons

44
Q

Copper oxide reduction example

A

Starts CuO is black, changes to pink/copper-coloured solid.
Condensation inside tube.

CuO (s) + H2 (g) -> Cu (s) + H2O (g)

H2 acts as a reducing agent.

Why is the excess hydrogen burned?
To prevent farmable H2 gas building up in the lab.

45
Q

What is a reducing agent?

A

A substance that will remove oxygen from a compound such as an oxide. It is oxidised.

46
Q

What is an oxidising agent?

A

A substance that will provide oxygen to a substance being oxidised. It is reduced.

47
Q

What happens to the magnesium atom as it forms the compound? 2Mg + O2 -> 2MgO

A

The magnesium atom loses to electrons and becomes a magnesium ion. Loss of electrons is oxidation.

Mg - 2e- -> Mg2+

48
Q

What happens to copper (II) ion as it forms the compound?

CuO + H2 -> Cu + H2O

A

The copper ion gains two electrons and becomes a copper atom. Gain of electrons is reduction.

Cu2+ + 2e- -> Cu

49
Q

Important oxidation and reduction reactions in industrial processes

A

(i) during the extraction of iron in the blast furnace
(ii) during extraction of aluminium by electrolysis
(iii) during production of ammonia in the Haber process

50
Q

Redox reactions: during the extraction of iron in the blast furnace

A

Iron(III) oxide + carbon monoxide -> iron + carbon dioxide
Fe2O3 (s) + 3CO (g) -> 2Fe (l) + 3CO2 (g)

The iron (III) ion has gained 3 electrons to become an iron atom. Gain of electrons is reduction. Fe3+ + 3e- -> Fe

51
Q

Redox reactions: during the extraction of aluminium by electrolysis

A 
Aluminium oxide (bauxite) -> aluminium + oxygen
2Al2O3 (s) -> 4Al (l) + 3O2 (g)

The aluminium ion has gained 3 electrons to become an aluminium atom. Gain of electrons is reduction. Al3+ + 3e- -> Al

52
Q

How is the oxide ion oxidised?

A

Two oxide ions gain 2 electrons each to become an oxygen molecule. The loss of electrons is oxidation.

53
Q

Redox reactions: during production of ammonia in Haber process

A

Nitrogen + hydrogen -> ammonia
N2 (g) + 3H2 (g) -> 2NH3 (g)

Reduction is gain of hydrogen.

Chemistry⚗️ (12 decks)

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