Ammonia

Uses

The Properties of Ammonia

Haber Process
Ammonia is commercially produced by the Haber Process. This is a flow chart to show the stages in the manufacture of ammonia, starting with the raw materials.

Ammonium Fertilisers
examples of ammonium fertilisers:

• Ammonium phosphate
• Ammonium nitrate
• Ammonium sulphate

The Effectiveness of Ammonium Fertilisers

It could be measured through determining its percentage of nitrogen content.  Plants needs nitrogens to grow.  Usually nitrogen is absorbed by plants in soluble nitrate ions from soils. Ammonium fertilisers consist of ammonium ions. Bacteria in the soils convert ammonium ions into nitrate ions which absorbed by plants together with water.  fFertiliser with higher percentage of nitrogen content is more effective.

To determine nitrogen content in ammonium fertilizer,

Comparison of Common Fertilizers

Fertiliser	Ammonium Sulphate, (NH4)2SO4	Ammonium Nitrate, NH4NO3
Molar mass	(14+(1)4)2+32+(16)4=132	14+(1)4+14+(16)3=80
Percentage of nitrogen in 1 mol	16/132 x 100% = 12.121%	28/80 x 100% = 35%

You should calculate the percentage of nitrogen content in each fertiliser and compare which one has higher percentage of nitrogen content. You'll know which fertiliser from the list is more effective.
From this example, ammonium nitrate is more effective.

Preparation of Ammonium Nitrate
Aim: To prepare ammonium nitrate
Material: 1 mol dm^-3 ammonia solution, NH3

Material : 1 mol dm^-3 ammonia solution, NH₃(aq), 1 mol dm^-3 nitric acid, NO₃, red litmus paper.

Apparatus : 250 cm³ beaker, glass rod, tripod stand, Bunsen burner, wire gauze, filter funnel, filter                                  paper, measuring cylinder, dropper, asbestos tile.

Procedure :

1.     Measure 50 cm³ of 1 mol dm^-3 nitric acid, HNO₃, with a measuring cylinder and pour into a 250 cm³ beaker.

2.     Add 1 mol dm^-3 ammonia solution, NH₃ (aq), drop by drop from a dropper into the nitric acid, HNO₃, while stirring until an excess amount is used (when ammonia is smelt).

3.     Pour the mixture into an evaporating dish.

4.     Boil the mixture until it evaporates to form a saturated solution.

5.     Cool the saturated solution to room temperature until crystal salts form.

6.     Filter and rinse the crystals with a little cold distilled water.

7.     Dry the salt crystals on a filter paper.

Analysis : Neutralisation occurs between nitric acid, HNO₃, and ammonia solution, NH₃(aq), and can                          be represented by the chemical equation below:

2NH₃(aq)   +   HNO₃   -->   NH₄NO₃

Conclusion : Ammonium nitrate, NH₄NO₃, salt can be prepared from the reaction between nitric acid,                               HNO₃, and ammonia solution, NH₃(aq).

Discussion :

1.     The mixture formed in the beaker can be tested from time to time with red litmus paper. The adding of ammonia solution, NH₃(aq), drops are stopped when the red litmus paper turns blue.

2.     The chemical equation of the reaction between ammonia aqueous solution and nitric acid, HNO₃, can be written as below:

HNO₃(aq)   +   2NH₄OH(aq)   -->   NH₄NO₃(aq)   +   2H₂O(l)

However, only about 2% of the dissolved ammonia forms ammonium and hydroxide ions.

References

-Longman Essential Chemistry SPM

Sulphuric Acid

Its Uses

Contact Process
Sulphuric Acid is manufactured through the contact process. This is a flow chart to show the steps in the production of sulphuric acid by the Contact Process, starting from the raw materials until you finally get the sulphuric acid.

Sulphur Dioxide
This is one of the by-products of the Contact Process. It causes environment pollution. But before that, let us see the  main sources of sulphur dioxide.



Now that we know the sources of sulphur dioxide, let us see the effects of sulphur dioxide towards human health.

• Severe airways obstruction, 
• Hypoxemia (insufficient oxygenation of the blood), 
• Pulmonary edema (a life threatening accumulation of fluid in the lungs)
• Skin irritation
• Eye irritation
• Smarting of the eyes and lachrymation (tears)
• Permanent pulmonary impairment (prolonged exposure)
• may cause Cancers such as lung cancer, stomach cancer or brain tumours

Acid Rain

Acid rain has a pH below 5.6 due mainly to the reaction of water vapour with sulfur dioxide and the oxides of nitrogen.

• Sulfur dioxide reacts with water to form sulfurous acid (H₂SO₃):SO₂(g) + H₂O(l)  H₂SO₃(aq)
• Sulfur dioxide (SO₂) can be oxidised gradually to sulfur trioxide (SO₃):2SO₂(g) + O₂(g) -----> 2SO₃(g)
  
• Sulfur trioxide (SO₃) reacts with water to form sulfuric acid (H₂SO₄):
SO₃(g) + H₂O(l) -----> H₂SO₄(aq)

source: http://www.nzdl.org

Effects of Acid Rain

References

-Longman Essential Chemistry SPM -http://www.nzdl.org

Composite Materials

Definition

Composite materials are produced from the combination of two or more different compounds such as alloys, metals, glass, polymers and ceramic.

Uses

Composite Materials	Composition	Properties	Uses
Reinforcement Concrete	• Cement • Gravel • Sand • Water • Iron or Steel	∆ Strong ∆ High textile strength ∆ Cheap	- Construction materials
Superconductor	• Niobium • Germanium	∆ Zero resistance ∆ Functions only under extremely low temperatures	- Transportation -Telecommunications - Astronomy industry - Medical field
Fibre Glass	• Silica • Sodium carbonate • Calcium carbonate	∆ Good insulator of heat and electricity	- Protective apparel for astronauts and firefighters
Fibre Optics	• Glass • Copper • Aluminium	∆ Enables information to be transmitted in light form at light speed	- Electrical cables - observe internal organs without surgery
Photochromic Glass	• Molten silica • Silver cloride	∆ Dark in colour when exposed to light and bright when in the dark	- Optical lenses - Glass windows
Ceramic Glass	• Produced by exposing glass that contains certain amounts of metal to ultraviolet rays and heating it at high temperatures		- Cooking materials - Rocket heads
Plastic strengthened with glass fibres	• Plastic • Glass	∆ Very strong ∆ Light ∆ Easily formed ∆ Withstands corrosion	- Helmets - Body of cars and aeroplanes - rods

Fibre Glass

Glass fibre is formed when thin strands of silica based or other formulation glass is extruded into fibres with small diameters suitable for textile processing.

Glass is unlike other polymers in that it has little crystalline structure and can be considered a substance frozen in its amorphous stage. The properties of the structure of glass in its softened stage are very much like its properties when spun into fibre.

Advantages of Photochromic Glass as Spectacles


The main advantage is that they will darken into a sunglass when exposed to U.V. light, thus obviating the need to carry a separate pair of sunglasses for protection against harmful U.V. rays from the sun.
Secondly, they provide a better visual health through UV protection than traditional prescription sunglasses.


References
-Longman Essential Chemistry SPM
-http://en.wikipedia.org/wiki/Photochromic_lens
-http://www.eyewearcanada.com/eyeglasses/advantages-and-disadvantages-about-photochromic-sunglasses/
-http://www.madabout-kitcars.com/kitcar/kb.php?aid=106

Glass and Ceramics

Main Components

Glass = silica @ silicon dioxide = obtained from sand

Ceramics = silicate = obtained from clay heated at high temp.

Comparison

Similarities

brittle

hard

electrical insulator

chemically inert

Difference

Glass	Ceramics
Transparent Recyclable	Not transparent Not recyclable

Uses of Glass

Uses of Ceramic

Chemical Composition, Properties, Uses of Glass

Type Of Glasses
Fused Glass	Soda Glass	Borosilicate Glass	Lead Glass
Composition
∆ Silica @ Silicon dioxide	∆ Sodium silicate & Calcium silicate	∆ Silica & Boron oxide	∆ Silica, Lead(||) oxide & Sodium oxide
Properties
• Very high melting point. • Not easy to change its shape. • Does not easily expand or shrink with changes of temperature. • Transparent to ultraviolet ray.	• Transparent. • Low melting point. • Easily broken • Cannot withstand heat and chemical reactions.	• Withstands heat and chemical reactions. • High melting point • Transparent to light and infrared ray but not to ultraviolet ray. • Expands and shrinks very little and only when temperature changes.	• Very transparent. • Shiny. • High reflective index. • High density.
Uses
∞ Lenses ∞ Spectacles ∞ Laboratory glassware ∞ Ultraviolet column	∞ Bottles ∞ Glass container ∞ Mirrors ∞ Electrical bulbs ∞ Glass Windows	∞ Bowls ∞ Plates ∞ Saucers ∞ Pots ∞ Cookware	∞ Lenses ∞ Prisms ∞ Glasses ∞ Ornamental items ∞ Crystals

References

-Longman Essential Chemistry SPM

Polymers

Definition
Polymers are long chains of molecules made from combination of many small molecules called monomers. Polymerisation is a process of combining monomers to form a long chain of molecules.

source: http://hsc.csu.edu.au/senior_science/options/polymers/2973/SS951.html

Naturally Occurring Polymers

Are polymers that occur naturally, like...:

1. Rubber
2. Cellulose
3. Starch
4. Protein
5. Fat
6. Nucleic acid

Synthetic Polymer

Synthetic polymers are often referred to as "plastics", such as the well-known polyethylene and nylon.

Uses of some General Synthetic Polymers with their Names and Monomer Units are as Follows:-

Name(s)	Formula	Monomer	Uses
Polyethylene low density (LDPE)	–(CH2-CH2)n–	ethylene CH2=CH2	Used in film wrap, plastic bags
Polyethylene high density (HDPE)	–(CH2-CH2)n–	ethylene CH2=CH2	Used in electrical insulation bottles, toys
Poly(vinyl chloride) (PVC)	–(CH2-CHCl)n–	vinyl chloride CH2=CHCl	Used in pipes, siding, flooring.etc.
Poly(vinylidene chloride) (Saran A)	–(CH2-CCl2)n–	vinylidene chloride CH2=CCl2	Used in seat covers, films etc.
Polystyrene (PS)	–[CH2-CH(C6H5)]n–	styrene CH2=CHC6H5	Used in toys, cabinets packaging etc.
Polyacrylonitrile (PAN, Orlon, Acrilan)	–(CH2-CHCN)n–	acrylonitrile CH2=CHCN	Used in rugs, blankets clothing etc.
Polytetrafluoroethylene (PTFE, Teflon)	–(CF2-CF2)n–	tetrafluoroethylene CF2=CF2	Used in non-stick surfaces, electrical insulation
Poly(vinyl acetate) (PVAc)	–(CH2-CHOCOCH3)n–	vinyl acetate CH2=CHOCOCH3	Used in latex paints, adhesives etc.
cis-Polyisoprene natural rubber	–[CH2-CH=C(CH3)-CH2]n–	isoprene CH2=CH-C(CH3)=CH2	Requires vulcanization for practical use and vulcanized rubber is used in tyres etc.
Polychloroprene (cis + trans) (Neoprene)	–[CH2-CH=CCl-CH2]n–	chloroprene CH2=CH-CCl=CH2	It is a synthetic rubber and is oil resistant so used in mats etc.

source: http://www.tutorvista.com/chemistry/synthetic-polymers-and-their-uses

Properties of Synthetic Polymers

Synthetic polymers are not biodegradable (not decomposed by microorganism). The careless disposal of items made from synthetic polymers such as plastic causes environmental pollution. The effects of burning and careless disposal of items made from synthetic polymers on the environments are as follow;

    (a) Burning of synthetic polymers

        ∆ Releases pollutants that endanger health such as smoke, gasses that are smelly, poisonous and corrosive such                          a          as sulphur dioxide, pollutants that cause acid rain and the green house effect.

    (b) Careless disposal of synthetic polymers

        ∆ Spoils the beauty of the environment.

        ∆ Causes flash floods during heavy rainfall.

        ∆ Endangers marine lifelike turtles that accidentally eat polymers such as plastics as food

The best way to manage used items made from synthetic polymers is to recycle them. Plastics that are biodegradable can be used instead to reduce environmental pollution.


References


-Longman Essential Chemistry Spm

Alloys

Pure Metals Atom Arrangement

Pure metal is soft and not very strong. Atoms of pure metals have similar sizes and shapes and are arranged closely but there is still space between the atoms. These spaces allow the atoms to slide along one another easily when force is applied. This property causes pure metal to be ductile, that is, ability to be stretched into a wire.

When knocked or hammered, the metal atoms slide along one another to fill the spaces between them. This property makes pure metal to be malleable, that is, can be shaped into various shapes.

Definition

An alloy is a compound formed from a mixture of metals and other elements. The foreign atom, which is an impurity atom, may be atoms of other metals or non-metal such as carbon. The process of forming an alloy is called alloying.

Purposes

There are a few reasons why alloys are made and they are to;

• make the metal harder and stronger
• prevent corrosion of the metal
• improve the appearance of the metal so it looks more attractive

These are a few examples;

99% Iron + 1% Carbon = Steel

74% Iron + 18% Chromium + 8% Carbon = Stainless Steel

90% Copper + 10% Tin = Bronze

70% Copper + 30% Zinc = Brass

75% Copper + 25% Nickel = Copper Nickel

97% Tin +2% Copper + 1% Antimony = Pewter

93% Aluminium + 3% Copper + 3% Magnesium + 1% Manganese = Duralumin

Alloy's Properties

Impurity atoms which are mixed may be larger or smaller than atoms of pure metals. These fill the empty spaces between the pure metal atoms. Impurity atoms can prevent the layers of metal atoms from sliding along another easily. Due to this, an alloy is harder and stronger than pure metals.

source: www.zimbio.com/CarbonMonoxideAla...m/Metals

Comparing The Hardness

Aim : To study the hardness and strength of an alloy as compared to a pure metal.

Problem Statement : Is brass (copper alloy) harder then copper?

Hypothesis : Diameter of depression on brass is smaller than diameter of depression on pure copper.

Variables : Manipulated:Type of metal block

                Responding :Diameter of depression

                Constant     :Height of metal ball

Material : Copper block, brass block, metal block, metal ball (steel), cellophane tape, thread.

Apparatus : Metre rule, 1 kg weight, retort stand.

Apparatus to study the hardness and strength of an alloy
source: Longman Essential Chemistry SPM

Procedure :

1. A steel ball is stuck to a brass block using cellophane tape.
2. A weight of 1 kg is hung at a height of 50 cm from the top of the brass block.
3. The weight is released so that it falls on the metal ball.
4. The diameter of depression formed on top of the brass block is measured using a metre ruler and the measurement is recorded in Table 9.5
5. Steps 1 to 4 are repeated twice on different spots on the brass block to obtain an average of the diameter
6. The experiment is repeated using a pure copper block.

Results :

Block	Diameter of depression
	1	2	3	Average diameter (mm)
Brass
Copper

Analysis : 

1. The depression made on the brass block is smaller than the depression made on the pure copper block.
2. Alloy can be  defined operationally as a material which is harder because the depresssion produced is smaller.

Conclusion :

1. Alloys are harder than pure metals.
2. The hypothesis made is accepted.

Comparing The Rate Of Rusting

Aim : To study the rate of rusting of an alloy as compared to pure metals.

Problem Statement : Does pure iron rust faster than stainless steel nail.

Hypothesis : Iron rusts faster than stainless steel.

Variables : Manipulated:Type of nail

                Responding :Intensity and amount of blue colour

                Constant     :Duration of rusting

Materials : Iron nails, stainless steel nails, agar, potassium hexacyanoferrate(|||) solution.

Apparatus : Test tube, test tube rack.

Apparatus to study the rates of corrosion of iron and stainless steel nails
source: Longman Essential Chemistry SPM

Procedure :

1. Hot agar solution is prepared and poured into two test tubes.
2. A little potassium hexacyanoferrate(|||) solution is added.
3. Iron nails are placed in one test tube and stainless steel nails in the other.
4. The apparatus is left for several days.
5. A change in colour is observed in the test tubes.

Observation :

Experiment	Observation
Iron nails	Dark blue spots form
Stainless steel nails	No dark blue spots

Analysis :

1. If iron corrodes (rust), iron(||) ions form. Potassium hexacyanoferrate(|||) solution can detect the presence of iron(||) by forming a dark blue colour.
2. If the nails corrode (rust), dark blue spots form in the agar.
3. Dark blue spots form only in the test tube containing the iron nails, so we can conclude that iron corrodes but not stainless steel.
4. Alloy can be defined operationally as a material which is resistant to corrosion becauseno dark blue spots are produced.

Conclusion :

1. Iron corrodes (rust) faster than steel.
2. The hypothesis made is accepted.

Uses of Alloys

Steel

use = To make bridges, vehicles, building skeleton and train tracks.

Properties = Strong, hard, withstand corrosion.

Stainless Steel

Use = To make kitchen utensils such as spoons, fork pots, pans and knives.

Properties = Strong, withstands corrosion, shiny.

Bronze

Use = To make medals, statues and bells.

Properties = Strong, hard, withstands corrosion.

Brass

Use = To make keys, musical instruments and ornaments.

Properties = Strong, shiny.

Pewter

Use = To make ornamental items such as picture frames and trophies.

Properties = Withstands corrosion, smooth and shiny surface.

Duralumin

Use = To make the body of aeroplanes and racing bicycles.

Properties = Strong, light, withstands corrosion.

Copper Nickel

Use = To make coins.

Properties = Strong, shiny silver colour.

References

-Longman Essential Chemistry SPM