Yellow booklet answers page 120 – 152 (last page of yellow booklet)
(Air, Water, The Haber Process, The Contact Process)

Air (page 120 – 131)
Pg 120
1. mixture, nitrogen, 79%
2. Noble gases, argon
3. glowing
4. B

Pg 121
5. A
6. B
7. B
8. B

Pg 122
9. C
10. B

Pg 123
1. fractional distillation, expansion, boiling points
2. carbon dioxide, soot, carbon monoxide
3. energy, water vapour, carbon dioxide
4. C
5. D

Pg 124
6. a) Incomplete combustion produces soot (carbon), carbon monoxide and water vapour;
carbon monoxide is poisonous
b) (i) respiration
(ii) glucose from foodstuff
c) (i) welding (using oxyacetylene flame)
(ii) carbon dioxide and water vapour
7. a) 79%, 20%
b) (i) presence of ice (from water vapour) will result in b.p. elevation of other liquefied gases; prevent blockage of the pipes by solid carbon dioxide and ice
(ii) nitrogen, argon, oxygen and krypton

Pg 125
1. carbon monoxide, unburnt hydrocarbons

Pg 126
2. oxides of nitrogen
3. incomplete
4. sulphur, sulphur dioxide, sulphurous acid (H2SO3)
5. ozone
6. nitrogen, carbon dioxide
7. desulphurization
8. D
9. A
10. A

Pg 127
11. a) methane
b) sulphur dioxide
c) ozone
d) unburnt hydrocarbons / carbon monoxide / nitrogen oxides
e) sulphur dioxide
f) nitrogen oxides

12. a) reacts with water vapour and oxygen in the atmosphere, forming acid rain, which corrodes buildings and destroys crops
b) (i) Mg(OH)2 + SO2 à MgSO3 + H2O
(ii) Neutralization
c) (i) MgSO3 à MgO + SO2
(ii) Manufacture of sulphuric acid in the Contact Process
(iii) Recycled / reused to absorb more sulphur dioxide

Pg 128
13. a) From secondhand smoke
b) Vol = 0.01% of 10 dm3 = 1 cm3
c) Incomplete combustion from the cigarette
d) Non-smoker
e) Forms carboxyhaemoglobin in blood, prevent transport of oxygen hence breathing difficulty.

Pg 129
carbon cycle
combustion, photosynthesis
carbon dioxide
a) CO + O3 à CO2 + O2
b) 2NO + 2CO à 2CO2 + N2
c) Catalytic converters

Pg 130
a) carbon dioxide, water vapour, energy
b) Respiration and combustion use up oxygen, carbon dioxide produced, photosynthesis uses up carbon dioxide, oxygen produced.
c) Melting of polar ice caps à flooding of coastal (low-lying) areas
Decrease in crop yields à desertification

Pg 131
a) (i) Incomplete combustion of fuel (petrol)
(ii) carbon dioxide 2CO + O2 à 2CO2
b) (i) 2NO2 à N2 + 2O2 or 2NO à N2 + O2
(ii) reacts with oxygen and water vapour in atmosphere, producing acid rain
c) (i) Substance that speeds up rate of reaction without forming products or used up (i.e. no chemically involved).
(ii) The purpose of the catalysts is different thus use of catalyst is different.
a) Ozone layer blocks harmful uv rays responsible for skin cancer. Ozone holes allow passage of uv rays.
b) Source: reaction of unburnt hydrocarbons with nitrogen dioxide in sunlight
Effect: breathing difficulties
c) (i) Try it out yourself. You should be able to draw the covalent molecule.
(ii) HFCs do not decompose, when exposed to sunlight, forming free radicals

Water (page 132 – 137)
Pg 132
anhydrous, white, blue
mineral salts
phosphates
eutrophication
D
D

Pg 133
a) (i) Atoms of same element with different mass numbers
(ii) H-1 : 1 proton, 0 neutron
H-2 : 1 proton, 1 neutron
b) (i) Helium does not react with oxygen / Mixture of H2 and O2 explodes with small sparks
(ii) Reaction of H2 and O2 very exothermic, great deal of heat produced to propel rocket / No reaction between helium and oxygen.

a) Compound: Formed from chemical reaction, 2 or more different substances chemically combined
Exothermic: Reaction in which (heat) energy is given out / produced
Elements: Substances that cannot be further decomposed into anything simpler
b) 2H2 + O2 à 2H2O
c) You should be able to draw the energy profile diagram on your own. It’s an exothermic reaction so the energy level of products is lower than the energy level of reactants.

Pg 134
Chlorine
activated carbon
desalination
a) filtration – to remove fine suspended solid particles
chlorination – to kill harmful bacteria

Pg 135
4. b) (i) Sea water
(ii) Nitrate
(iii) Distillation
c) (i) Salt
(ii) Desalination
d) Test 1: White anhydrous copper (II) sulphate à blue
Test 2: Blue cobalt (II) chloride paper à pink

Pg 136
5. a) (i) D
(ii) B
(iii) Na2SO4, NaNO3, Ca(NO3)2 but not CaSO4 (insoluble)
(iv) A. High concentration of sulphate ions and nitrate ions found in fertilizers.
b) 4Fe2+ (aq) + 4H+ (aq) + O2 (g) à 4Fe3+ (aq) + 2H2O (l)
How to do it???
1) Write out the reactants, ions, compounds, etc involved.
2) Balance the number of ions / atoms / etc on each side of the equation
3) Check to ensure that the overall charge on each side of the equation is the same. The charges do not necessary have to add up to 0 on both sides.

Pg 137 (Crossword puzzle)
1) Ammonia
2) Anhydrous
3) Sodium
4) Margarine
5) Extinguished
6) Drink
7) Kitchen
8) Neutral
9) Lighted
10) Decompose
11) Explosion
12) Natural
13) Liquid
14) Distillation
15) Non

The Haber Process (page 138 – 146)
Pg 138
alkaline, moist, blue
ammonium, alkali

Pg 139
Haber, 200, 450°C
reversible
A
B
D
D

Pg 140
a) Increase pressure, increases %NH3
b) (i) 27%
(ii) Advantage: Low temp makes reaction slow. Hence at 450°C, reaction proceeds faster than at 350°C.
Disadvantage: At same pressure, %NH3 at 450°C is lesser than %NH3 at 350°C.
c) Catalysts are not used up in the reaction and can be recycled.
d) Moist red litmus turns blue in ammonia.
Lighted splint extinguished with ‘pop’ in hydrogen.
Glowing splint rekindled in oxygen.

Pg 141
proteins
eutrophication
nitrogen

Pg 142
C
D
B
A
a) %N in NaNH2 = 35.9% (to 3 s.f.)
Mass required to produce 14 tonnes nitrogen = 39

%N in (NH2)2CO = 46.7% (to 3 s.f.)
Mass required to produce 14 tonnes nitrogen = 30

Thus urea (NH2)2CO provides more nitrogen per tonne of fertlizers.

Pg 143
8. b) High solubility of nitrate ions washed into nearby rivers (leaching); growth of algae in rivers encouraged; algae dies and decays, oxygen is used up; oxygen content depleted / decreased

c) (i) 2NH4NO3 + Ca(OH)2 à Ca(NO3)2 + 2H2O + 2NH3
(ii) Reduce acidity of soil
(iii) Calcium hydroxide reacts with ammonium nitrate, producing calcium nitrate which is a neutral salt, water and ammonia.
Nitrogen is displaced from fertilizers, and not used to increase nitrogenous content of the soil; thus wasted.

Pg 144
9. a) (i) 2850 kg (estimated from half of (2600 kg + 3100 kg))
(ii) From 20 kg of phosphorus added onward, very slight increase to potato yield per kg.
b) (i) Mr of Ca(H2PO4)2 = 234
(ii) %P in Ca(H2PO4)2 = 26.5% (to 3 s.f.)
Mass to be provided = 56.6 kg (to 3 s.f.)
(iii) Potassium nitrate, KNO3

Pg 145
10. a) Necessary for plant growth and repair of plant cells (synthesis of proteins)
b) 2NH3 + H2SO4 à (NH4)2SO4
c) %N in NH4NO3 = 35%
%N in (NH4)2SO4 = 21.2%
%N in urea = 46.7% (highest %N by mass)
d) You should be able to draw the covalent molecule of ammonia. If not, please check your textbook.

Pg 146 (Fun with Chemistry)
UREA
POTASSIUM
CHLOROPHYLL
AMMONIUM NITRATE
PROTEIN
BACTERIA
LIME
NITROGEN
TRACE ELEMENTS


The Contact Process (pg 147 – 152)
Pg 147
S8, low, yellow
sulphur dioxide, pungent, acid rain
preservative, bleach
D

Pg 148
SO2, vanadium (V) oxide, 450°C, 1 atm
water, sulphuric acid, oleum
fertilizers
C

Pg 149
C
E
D
B

Pg 150
a) Manufacture of fertilizers
b) Sulphuric acid with barium nitrate solution; white precipitate of barium sulphate produced
c) (not in graph) As an electrolyte in car batteries / making of detergents
d) Reaction: H2SO4 + MgCO3 à MgSO4 + CO2 + H2O
Observation: Effervescence / bubbles of gas produced
Products: magnesium sulphate, carbon dioxide and water

10. a) (i) Ammonium sulphate
(ii) Plants need other elements (like potassium and phosphorus) for healthy growth, thus other fertilizers needed to provide the K and P.

Pg 151
10. b) (i) 3H2SO4 + Fe2O3 à Fe2(SO4)3 + 3H2O
(ii) Acid will react with iron in steel sheets.
c) (i) 2SO2 + O2 2SO3
(ii) 450°C, 1 atm, with vanadium (V) oxide as catalyst
(iii) Sulphur dioxide gains oxygen, forming sulphur trioxide, thus oxidation (gain of oxygen) OR
Increase in oxidation state of sulphur from +4 to +6 thus oxidation.
d) (i) Use of sulphur dioxide: as a food preservative;
as a bleaching agent for wood pulp
(ii) Add / pass / bubble gaseous compound into
1. acidified potassium dichromate (VI) solution; turns from orange to green
2. acidified potassium manganate (VII) solution; turns from purple to colourless

Pg 152 (Fun with Chemistry)
1. sulphide
2. sulphurous
3. electrolyte
4. pickling
5. hydrogen
6. anhydride
7. trioxide
8. fertilizers (end of yellow bookle

Orgnic Chemistry

Organic Chemistry Class 401 / 404

Important terms you should know:
1. addition reaction (TB pg 425)
Reaction in which a molecule (element or compound) adds to an unsaturated compound to form a single new compound (referred only to alkenes).

2. cracking (TB pg 428)
The breaking down of long chain hydrocarbon molecules with heat and/or catalyst to produce smaller hydrocarbon molecules or hydrogen.

3. fermentation (TB pg 436)
The conversion of glucose (or simple sugars) by yeast into carbon dioxide and ethanol.

4. functional group (TB pg 416)
An atom or group of atoms that gives characteristic properties to an organic compound.

5. homologous series (TB pg 418)
Family of organic compounds with same general formula (same functional group), having similar chemical properties, showing slight gradation in the physical properties, and having each member differ from the next by a –CH2 unit.

6. hydrocarbons
Organic compounds made up of the elements hydrogen and carbon only.

7. polymerization (TB pg 449, polymers)
Chemical reaction in which simple molecules (called monomers) react with each other to form large molecules (called polymers).

8. saturated
Containing single covalent bonds in its carbon atoms only.

9. unsaturated
Containing one or more double covalent carbon-carbon bonds.
(polyunsaturated means containing more than one / many double carbon-carbon covalent bonds.)

10. esterification (TB pg 443, ester)
Chemical reaction between an alcohol and a carboxylic acid, using concentrated sulphuric acid as catalyst, to produce esters (sweet smelling liquids).


Alkanes
Alkenes
Alcohols
Carboxylic acids
Definition
(n : number of carbon atoms)
Saturated hydrocarbons having the general formula CnH2n+2.
Unsaturated hydrocarbons having the general formula CnH2n.

(functional group C=C)
Organic compounds containing the hydroxyl group, -OH, with general formula CnH2n+1OH.
Organic acids containing the carboxyl group, -COOH, with general formula, CnH2n+1COOH, where n starts from zero.
First five members
(names and chemical formula)
Methane, CH4
Ethane, C2H6
Propane, C3H8
Butane, C4H10
Pentane, C5H12
Ethene, C2H4
Propene, C3H6
Butene, C4H8
Pentene, C5H10
Hexene, C6H12
Methanol, CH3OH
Ethanol, C2H5OH
Propanol, C3H7OH
Butanol, C4H9OH
Pentanol, C5H11OH
Methanoic acid, HCOOH
Ethanoic acid, CH3COOH
Propanoic acid, C2H5COOH
Butanoic acid, C3H7COOH
Pentanoic acid, C4H9COOH
Physical properties
(Trends exhibited down the group)
1. Melting point and boiling point increases.
2. Viscosity and density increases.
3. Less flammable; smokier smoke produced.
1. Melting point and boiling point increases.
2. Viscosity and density increases.
3. Less flammable; smokier smoke produced than alkanes.
1. Melting point and boiling point increases (first 4 members are liquids at rtp).
2. Solubility decreases.

1. Melting point and boiling point increases.
2. Solubility decreases.



Alkanes
Alkenes
Alcohols
Carboxylic acids
Chemical properties
1. Complete combustion gives carbon dioxide and water vapour as only products.
2. Incomplete combustion produces carbon (soot) and/or carbon monoxide and water vapour.
3. Substitution reactions occur with halogens (F2, Cl2, Br2) in uv light.


Alkanes are generally unreactive due to their saturation.
1. Complete combustion gives carbon dioxide and water vapour as only products.
2. Incomplete combustion produces carbon (soot) and /or carbon monoxide and water vapour.
3. Undergo addition reactions with
Ÿ hydrogen (hydrogenation; making of margarine);
Ÿ bromine (bromination; test for unsaturation);
Ÿ steam (production of alcohols) and
Ÿ other alkenes (polymerization)
1. Complete combustion gives carbon dioxide and water vapour as only products.
2. Oxidation
Ÿ In lab using acidified K2Cr2O7 forming carboxylic acid.
Ÿ By exposure to air (oxygen), forming carboxylic acid, due to action of bacteria in air.
3. Esterification with carboxylic acid, producing esters and water.
1. Complete combustion gives carbon dioxide and water vapour as only products.
2. Weak acids, having same chemical reactions as inorganic acids with reactive metals, bases and carbonates.
3. Esterification with alcohols, producing esters and water.
Source
1. Crude oil / petroleum
2. Cracking of larger hydrocarbons
1. Crude oil / petroleum (minor source)
2. Cracking of larger hydrocarbons
1. Catalyzed addition of steam to alkenes
2. Fermentation of simple sugars (glucose)
1. Oxidation of alcohols by
Ÿ acidified K2Cr2O7
Ÿ bacteria in air


Alkanes
Alkenes
Alcohols
Carboxylic acids
Uses
1. As a fuel.
1. To form plastics through addition polymerization.
1. As a fuel.
2. As a solvent.
3. To make alcoholic beverages.
4. To form esters.
1. To form esters.
Website for reference: http://www.chemguide.co.uk/orgpropsmenu.html

Important chemical reactions
Brief description
Conditions
Products
Chemical equations / Observations (if any)
Alkanes
Substitution with halogens
(using methane to illustrate)
Presence of uv light;
F2 / Cl2 / Br2
(with chlorine)
Mixture of chloromethane (CH3Cl); dichloromethane (CH2Cl2); trichloromethane (CHCl3); tetrachloromethane (CCl4); and hydrogen chloride (HCl)
CH4 + Cl2 à CH3Cl + HCl
CH3Cl + Cl2 à CH2Cl2 + HCl
CH2Cl2 + Cl2 à CHCl3 + HCl
CHCl3 + Cl2 à CCl4 + HCl
Any or all of the above can occur at the same time.
Reaction stops when methane and/or chlorine are used up.
Alkenes
Addition reaction with hydrogen
(Hydrogenation of ethene)
Approx 200°C;
nickel catalyst;
hydrogen gas
Ethane
Generally, the corresponding alkane is obtained.
C2H4 + H2 à C2H6

Generally, CnH2n + H2 à CnH2n+2


Important chemical reactions
Brief description
Conditions
Products
Chemical equations / Observations (if any)
Alkenes
Addition reaction with bromine
(Bromination of ethene)
Bromine solution
Dibromoethane
C2H4 + Br2 à C2H4Br2
Reddish brown bromine solution is decolourised.
A colourless product is obtained.
This is also known as the test for unsaturation.
Alkenes
Addition reaction with steam
(using ethene to illustrate)
300°C; 65 atm;
phosphoric acid as catalyst
Ethanol
Generally, the corresponding alcohol is obtained.
C2H4 + H2O à C2H5OH

Generally, CnH2n + H2O à CnH2n+1OH
Alkenes
Addition polymerization
(using ethene to illustrate)
High pressure;
high temperature;
catalyst

(1000 atm; 200°C)
Poly(ethene)

Generally, name of polymer is obtained by putting the monomer in brackets and adding ‘poly’ in front of the brackets.
E.g. polymerization of ethene

n CH2 = CH2
ethene poly(ethene)
Catalytic cracking
(for both long-chained alkanes and alkenes)
High temperature; catalyst

(about 600°C; aluminium oxide or silicon (IV) oxide as catalyst - aluminosilicates)
Mixture of short-chained alkenes and mixture of short-chained alkanes or H2 (g)
E.g. hexane à butane and ethene
C6H14 à C4H10 + C2H4
Alternatively, hexane à ethene + hydrogen
C6H14 à 3C2H4 + H2
Products obtained depend on conditions imposed.

The total number of carbon atoms and hydrogen atoms must be the same before and after cracking.


Important chemical reactions
Brief description
Conditions
Products
Chemical equations / Observations (if any)
Alcohols
Oxidation to carboxylic acids
(using ethanol to illustrate)
Oxidizing agent such as acidified K2Cr2O7 or by exposure to air
Ethanoic acid and water

Generally the corresponding carboxylic acid will be obtained.
ethanol + oxygen from O.A. à ethanoic acid + water
C2H5OH + 2[O] à CH3COOH + H2O
Orange acidified potassium dichromate (VI) turns green.

ethanol + oxygen from air à ethanoic acid + water
C2H5OH + O2 à CH3COOH + H2O
A sour liquid is obtained.
Fermentation of simple sugars (glucose)
Enzymes in yeast;
37°C;
simple sugars;
absence of air
Ethanol and carbon dioxide
glucose solution à ethanol + carbon dioxide
C6H12O6 à 2C2H5OH + 2CO2
Carboxylic acids
Reaction with reactive metals
(using ethanoic acid to illustrate)
Reactive metals
(e.g. Na)

The reactivity series of metals applies.
Organic salt + hydrogen gas
(e.g. sodium ethanoate + hydrogen)
ethanoic acid + sodium à sodium ethanoate + hydrogen
2CH3COOH + 2Na à 2CH3COO-Na+ + H2

Effervescence; colourless gas produced, extinguished lighted splint with ‘pop’.
ethanoate ion = CH3COO-


Important chemical reactions
Brief description
Conditions
Products
Chemical equations / Observations (if any)
Carboxylic acids
Reaction with bases / alkalis
(using ethanoic acid to illustrate)
Bases or alkalis
(e.g. NaOH)
Organic salt + water
(e.g. sodium ethanoate + water)
ethanoic acid + sodium hydroxide
à sodium ethanoate + water
CH3COOH + NaOH à CH3COO-Na+ + H2O

This reaction is also called a neutralization reaction.
Carboxylic acids
Reaction with carbonates
(using ethanoic acid to illustrate)
Carbonates
(e.g. Na2CO3)
Organic salt + water + carbon dioxide gas
(e.g. sodium ethanoate + water + carbon dioxide)
ethanoic acid + sodium carbonate
à sodium ethanoate + water + carbon dioxide
CH3COOH + Na2CO3 à CH3COO-Na+ + H2O + CO2

Effervescence; colourless gas produced, forms white precipitate with limewater.
Esterification
(between carboxylic acids and alcohols)
(using ethanoic acid and ethanol to illustrate)
Ethanoic acid;
ethanol;
few drops of concentrated H2SO4 as catalyst;
heat
Ester + water
(e.g. ethyl ethanoate + water)

A molecule of water is always produced when a molecule of carboxylic acid reacts with a molecule of alcohol.
ethanoic acid + ethanol à ethyl ethanoate + water
CH3COOH + C2H5OH à CH3COOC2H5 + H2O

Generally, the –H is removed from the alcohol while the –OH is removed from the carboxylic acid to form the water of molecule produced during esterification.
First part of name of ester comes from the alcohol (from –ol change to –thyl) while second part of name of ester comes from the carboxylic acid (from –oic acid change to ­–ate).


Description
Reaction
Conditions
Products
Structure of product
Esterification
(Formation of ethyl ethanoate)
Heat and few drops of concentrated H2SO4 as catalyst
Ethanol and ethanoic acid
Ethyl ethanoate
(known as esters, which are generally sweet smelling liquids / oils)



Refer to TB pg 442 for structure of ethyl ethanoate
Condensation polymerization of esters
Heat and few drops of concentrated H2SO4 as catalyst
Monomers:
Alcohol and carboxylic acid
Polyesters
Synthetic polyester:
Terylene
Natural polyester:
Fats
Refer to TB pg 456 (Structure of terylene polymer)
Condensation polymerization of amides
Heat and a few drops of concentrated H2SO4 as catalyst
Monomers:
Alcohol and amine
Polyamides
Synthetic polyamide:
Nylon
Natural polyamide:
Proteins
Refer to TB pg 455 (Structure of nylon polymer)
Addition polymerization
of ethene
High pressure (1000 atm); High temperature (200°C);
Catalyst
Monomer:
Ethene
Poly(ethene)
(also called polythene)





Refer to TB pg 450 for structure of poly(ethene) polymer
Refer to TB pg 452 Table 28.2 for details of other common polymers
End of brief notes on Organic Chemistry
© Mrs Annie (XMS Science Dept 2007)

27062007

Since no one is updating, here I am with a dozen of photos!!

The first photo following this sentence.. Can you make out who he is? Does it look misleading? Haha... Just to commemorate today as St. John's day, haha.

Oh yah. Please do NOT crop off the words if you choose to rip the photos from here. Don't be so cheap- we have enough cheap things in the world already.

The next is Tey Siang, sabotaged at St. Margaret Secondary to represent our school. The man, by the way, is the duno-what-you-call-it people who deal with the terrorists.

The following were taken during the March holidays- can you guess what made her laugh that hard? It shouldn't be that hard..

And the following? It's funny how our AMaths lesson became a picture lesson.. Refer to whiteboard.

If you think our school's discipline pictures are funny..
..you haven't seen worse.

Another significant thing which took place?
INTERACTION..
...until she finds someone even better..? Kidding.
And you know what? Sometimes when we attend conferences, the most exhausted people are usually the ones who bring us there.

On a random note, spot an extremely far-fetched mistake in the following STomp post:

Next, our supposedly-interesting URA trip- the last we saw of Evelyn's long hair.
First stop: The superwoman does the talk..

..and the bird does it ALL.

Anyone knows how Jay Chou walks? Refer to below.

In URA- Funny Four acting cute.

Can you recognise them? LOL.

Now a better shot:
Class photo:

And the man in the limelight?

ALI.
Can you identify the three guys below?

How about the following three?

And the following? That was the last we saw of his hair.

Some exploration..

Some slack..
See how ALAF can entertain Joshua.

And the last photo taken before we left the gallery- sorry ah, Yie Sing was supposed to be captured in the shot on the other side of Mr sWong.

Can others update too? LOL.

REMEMBER TO BRING ODT TOMORROW.

16062007

HCL STUDENTS PLEASE TAKE NOTE:

Please be kind enough to inform others also, including those from other classes. And um. Feel free to post this notice anywhere- other class blogs, your own blogs, whatever.

Oh yah. I haven't had a chance to drink Whatever yet.. =((