Topic 1 Planet Earth2

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CCllaassss:: ____________

TTooppiicc II –– PPllaanneett EEaarrtthh NNSSSS CChheemmiissttrryy 1111--1122

1. The atmosphere

2. The Ocean

3. Rocks and Minerals

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Topic I – Planet Earth by Ricky Tsui

www.hksciblog.edublogs.org

Teaching content (from Curriculum and Assessment Guide, S4-6 Chemistry)

(1) Compulsory Part

Topic Suggested teaching hours

I. Planet earth 8 hours (4.0%)

II. Microscopic world I 24 hours (12.1%)

III. Metals 22 hours (11.1%)

IV. Acids and bases 27 hours (13.6%)

V. Fossil fuels and carbon compounds 20 hours (10.1%)

VI. Microscopic world II 8 hours (4.0%)

VII. Redox reactions, chemical cells and electrolysis 26 hours (13.1%)

VIII. Chemical reactions and energy 9 hours (4.5%)

IX. Rate of reaction 9 hours (4.5%)

X. Chemical equilibrium 10 hours (5.1%)

XI. Chemistry of carbon compounds 27 hours (13.6%)

XII. Patterns in the chemical world 8 hours (4.0%)

Total: 198 hours

(2) Elective Part (Select any 2 out of 3)

Topic Suggested teaching hours

XIII. Industrial chemistry 26 hours

XIV. Materials chemistry 26 hours

XV. Analytical chemistry 26 hours

Total: 52 hours

(3) Investigative Study (for taking 2014 examination and thereafter only)

XVI. Investigative study in chemistry 20 hours

Total: 20 hours

Assessment (from Curriculum and Assessment Guide, S4-6 Chemistry)

Component Outline Weighting Duration

Public examination

Paper 1 Compulsory Part 60% 2½ hours

Paper 2 Elective Part (a choice of two out

of three elective topics) 20% 1 hour

School-based assessment

(SBA)

Practical related tasks and non-practical

related tasks 20% N/A



(Extracted from Curriculum and Assessment Guide, S4-6 Chemistry)



1. The Atmosphere



1. The Atmosphere

Composition of air

Air is a m of gases making up the atmosphere.

The approximate composition of air (by volume):

Composition Percentage by volume

Nitrogen

Oxygen

Noble gases

Carbon dioxide

Water vapour variable

Separation of oxygen and nitrogen

Oxygen and nitrogen can be separated from air by f d

of liquid air because they have different b p .

Noble gases can also be obtained by fractional distillation of liquid air.

(from Curriculum and Assessment Guide, S4-6 Chemistry)

How to separate O2 and N2 from the air? Base on what difference?



Steps of fractional distillation of liquid air:

i) Air is purified to remove dusts, carbon dioxide and etc.

ii) Purified air is cooled to about -200 °C. The air changes to liquid at this

temperature.

iii) The liquid air is warmed up slowly.

iv) Nitrogen (b.p. = -196 °C) boils and is separated from the mixture first.

v) Oxygen (b.p. = -183 °C) boils and is separated from the mixture at a

_____________ temperature.

[10CE/MC]

[05CE/MC]

3. The table below gives some information about certain components in a sample of liquefied air.

Component Boiling point/oC

argon -186

nitrogen -196

oxygen -183

In what order are these components distilled out when the sample undergoes fractional distillation?

A. nitrogen, oxygen, argon

B. nitrogen, argon, oxygen

C. oxygen, argon, nitrogen

D. oxygen, nitrogen, argon



Test for oxygen

Oxygen r a g s .

Note: Oxygen is not tested by burning splint.

_____________ splint is used to test hydrogen.

A ‘______’ sound will e given out.

[10CE/4(a)/ 1 mark]

Suggest a test for O2 Remember: “how” + “result”



2. The Ocean



2. The Ocean

Composition of sea water

Sea water is a mixture of salts,

dissolved gases, water, etc.

The approximate composition of sea water

(by mass):

Composition Percentage by mass

Water 96.5

Sodium chloride 2.4

Magnesium chloride 0.5

Sodium sulphate 0.4

Calcium chloride 0.1

_____________________ (common salt) and ___________

are two important components of sea water.

Extraction of common salt from sea water

To extract sodium chloride (common salt) from sea water,

1. f____________,

2. e_____________

3. and c_______________ are employed.

Filtration is a method for separating _______________ solid from a liquid.




We can separate mud from sea water by f________________:

set-up for filtration

R____________: Solid remains in the filter paper.

F____________: The liquid that passes through the filter paper.

After filtration, sodium chloride is obtained from the sea water (filtrate) by

evaporation or crystallization.

Evaporation is a method for separating ______________ solid from a solution.

When sea water is evaporated to dryness, sodium chloride is left.

!?

Draw a labeled diagram for filtration set-up.



Note:

The sodium chloride obtained is in powder form.

The sodium chloride obtained may contain some impurities, e.g. other minerals in

sea water.

C__________________ is a method used to obtain pure dissolved solid (solute)

from a solution.

Pure sodium chloride crystals can be obtained from a saturated solution of sea

water:

i) Warm the filtrated sea water in an evaporating dish until a saturated solution is

obtained.

ii) Cool the solution slowly. Large sodium chloride crystals are obtained.

iii) Filter off the crystals. Wash them with small amount of cold water and dry them

with filter paper.

growing sodium chloride crystals



A s______________ solution is a solution containing the m_____________

amount of solute (sodium chloride) at a certain t_______________ .

Small crystals are obtained if the solution is cooled quickly.

Filtration can be employed to separate a solute from a solution.

[10CE/MC]

[09CE/7(a)/2 marks]



Isolation of pure water from sea water

Simple distillation is a method for separating pure liquid from a solution.

Pure water can be obtained by simple distillation of sea water using simple

apparatus or 'Quickfit' apparatus.

Distillation using simple apparatus:

Thermometer is used to measure the temperature of the vapour (steam)

actually distilled over. Hence the thermometer bulb should be placed at the

opening of the delivery tube.

Anti-bumping granules are added to ensure smooth boiling.

The end of the delivery tube should be placed above the distillate. Otherwise,

sucking back of cold distillate into the hot boiling tube will occur if the heat source

is removed. This may crack the hot boiling tube.

Condenser is used to condense the steam.

How to prevent sucking back?



fractional distillation set-up using “Quickfit” apparatus A box-set of “Quickfit” apparatus

Drawing distillation set-up



Test for substances in sea water

Test for sodium

Flame test is used to show the presence of metals in some compounds.

Different metals give different flame colours.

Procedures of the flame test for sodium:

i) A clean platinum wire is dipped into concentrated hydrochloric acid.

ii) It is then dipped into powdered sodium chloride.

iii) The wire is heated in Bunsen flame.

Flame colours for compounds containing metals:

Compounds containing Flame colour

Sodium

Potassium

Calcium

Copper

[05CE/MC]

5. When a flame test is performed on copper(II) chloride, what is the colour of the flame observed ?

A. golden yellow

B. pale purple

C. brick-red

D. bluish-green

How to carry out flame test? Color of different flames?



Test for chloride

Procedures for showing the presence of chloride in a solution:

i. Excess dilute nitric acid is added to the solution

ii. Silver nitrate solution is then added to the solution.

test for chloride ions

(We can also mix excess dilute nitric acid and silver nitrate solution first to give

acidified silver nitrate solution.)

In the presence of chloride, white precipitate is formed.

Ag+(aq) + Cl-(aq) AgCl(s)

colourless colourless white precipitate

Excess dilute nitric acid prevents formation of other white insoluble

compounds (e.g. silver carbonate and silver sulphite) which may mislead

the result.

How to test the presence of Cl-(aq)

Equation for ppt. formation



Test for water

Water turns dry cobalt(II) chloride paper from blue to pink.

Water can also turn anhydrous copper(II) sulphate from white to blue.

The colour change of dry cobalt(II) chloride paper or anhydrous copper(II)

sulphate only shows the presence of water in a sample. It does not show

that the sample is pure water.

[10CE/2(b)(ii)/2 marks]

How to test the presence of water?




Rocks

The substances which make up rocks

are called minerals.

A mineral is a naturally occurring substance

(element or compound) with definite chemical composition.

Most rocks are mixtures of minerals.

Extraction of metals from their ores

An ore is a rock containing the mineral from which a particular m_______ can be

obtained.

Examples of some common ores:

Ore Metal in the ore

Haematite

Bauxite Aluminum

Copper pyrite

different kinds of metal ores




The main steps involved in getting a metal from its ore:

i) M__________ of the ore (digging the ore from the ground)

ii) Separation of the useful mineral from waste

iii) E___________ of the metal from the mineral, e.g.

Physical separation such as p___________ for gold

H__________________________

Heating the ore with c__________ (carbon reduction)

E_____________ of molten ore

iv) Purification of the impure metal

gold panning iron-making blast furnace electrolysis of molten lead (II) bromide

Name of method for extracting metal from its ores



Limestone, chalk and marble

L_____________(石灰石), c________(白堊) and m_________(大理石) are three

common materials in the Earth's crust.

They are different forms of c__________ c_____________.

limestone chalk marble

Chalk is the softest whereas marble is the hardest.

Uses of limestone, chalk and marble:

Forms of calcium carbonate Uses

Limestone

Cement Glass Materials for construction

Bauxite Materials for construction

Copper pyrite Making floor

[06CE/MC]

25. Which of the following substances contain calcium carbonate as the main chemical constituent?

(1) limestone

(2) chalk

(3) marble

A. (1) and (2) only

B. (1) and (3) only

C. (2) and (3) only

D. (1), (2) and (3)



[10CE/MC]

Action of water, acid and heat on calcium carbonate

Action of water

Calcium carbonate is i________________ in water.

Action of acid

Calcium carbonate reacts with dilute hydrochloric acid to give calcium

chloride, water and carbon dioxide:

CaCO3(s) + 2HCl(aq) ___________________________________

Word equation: ______________________________________________

Observation:

Calcium carbonate dissolves to give a c______________ solution.

E_________________ (bubbles of carbon dioxide are evolved) occurs.

Action of heat

Calcium carbonate decomposes on heating to give c_________ o_________

(quicklime or lime) and carbon dioxide:

CaCO3(s) _______________________ [Q___________ (生石灰)]

Chemistry of calcium carbonate: 1. + water 2. + acid 3. heating

Writing word equation or chemical equation



Word equation: ______________________________________________

When calcium oxide is added to water,

heat is released and c___________ h____________ (slaked lime) is formed:

CaO(s) + H2O(l) ___________________ [S_________ l_______ (熟石灰)]

Word equation: ______________________________________________

Calcium hydroxide is slightly soluble in water. The saturated calcium

hydroxide solution formed is called limewater.

water + Ca(OH)2(s) ____________________ (l_______ w________)

Word equation: ______________________________________________

quicklime slaked lime

Tests for calcium and carbonate in calcium carbonate

Calcium compounds give a b_______ r______ f_______ in the flame test.

Carbonate can be tested by adding dilute hydrochloric acid to the calcium

carbonate. The gas evolved (carbon dioxide) turns limewater milky due to

formation of insoluble calcium carbonate:

Ca(OH)2(aq) + CO2(g) ________________________

(Milky)



.

[08CE/MC]

42. Calcium carbonate can be obtained from quicklime through two processes as shown below.

quicklime limewater calcium carbonate

Process 1 Process 2

Which of the following combinations is correct?

Process 1 Process 2

A. adding water adding Na2CO3(aq)

B. adding Na2CO3(aq) adding water

C. adding water heating

D. heating adding water

[04CE/MC]

11. A white solid is found around the mouth of a reagent bottle containing lime water. The white solid is

likely to be

A. calcium oxide.

B. calcium sulphate.

C. calcium carbonate.

D. calcium hydrogencarbonate.

Test for carbonate salt Set-up for limewater test



[10CE/6(a)(b)(c)/5 marks]



[09CE/1/5 marks]



[05CE/1(a)(Ii)/2 marks]

1. (a) Calcium is an element in Group II of the Periodic Table.

(ii) Suggest a test to show that marble is a calcium-containing substance.

Topic 1 Planet Earth2

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Transcript of Topic 1 Planet Earth2