CHEMY.4M2.7FUEL

FUEL

Is the form of matter that is used to produce energy or power by burning

e.g.

Fuels of wood,

natural gas .

These fuels are used as source of energy or power in homes, industries and in transportation in ruining automobiles, rails and airplane

SOURCE OF FUEL

The materials used as fuels are generally grouped as

1.    BIOMASS fuel

2.    fossils fuel

BIOMASS FUELS

Are fuels which originate from recent materials of plant and animals

 example are

 dry wood,

dry weed,

agricultural wastes

 biogas.

FOSSIL FUELS

Are fuels which are preserved in the earth crust as remains of plants and animals example

 coal,

 petroleum,

natural gas

HOW FOSSIL FUEL OCCURS

It is believed that millions of years ago animals and vegetable matters were burried beneath the earth due to certain natural calamities such as flood, earthquakes cyclones, and storms

Under high temperature and pressure inside the earth these materials were subjected to decomposition in absence of air to from coal, petroleum and natural gas.

COAL

Is a natural occurring black material. It consists of large percentage of carbon mixed with some other minerals.

Coal is the most abundant commercial energy resources in Tanzania, the coal mines in southern part of Tanzania: Lindi, songwe, and kiwira. Products of coal are: coal tar, coke, ammonial liquor

USES OF COAL PRODUCT

1.Coal tar is used to make other chemicals like benzene, toluene, phenol and naphthalene

2. Coal gas is used as fuel.

3. Used as reducing agents in extraction of metals e.g. Extraction iron metal

3. Used as reducing agents in extraction of metals e.g. Extraction iron metal

4.Ammonial liquor is used in manufacture of fertilizer.

PETROLEUM (CRUDE OIL)

Is a complex mixture of more than hundred hydrocarbons and is highly viscous liquid and it has characteristic bad smell.

Origin of petroleum Petroleum has been produced in millions years by the bacteria decomposition, animals and plants which were buried underground in the earth crust due to earthquake, cyclone, and storm.

DRILLING OF OIL WELLS

Petroleum Is obtained by drilling holes in the earth crust at the place where the presence of oil is indicated by surveyors Also can be obtained by drilling under the sea (what a called shore wells)

PETROLEUM REFINING

Is the mixture of different materials, it must be separated into useful products. The process used to separate is called refining of petroleum.

The method used to refine petroleum is known as fraction distillation

Products of petroleum

The product of petroleum are

                                      I.        Kerosene,

                                    II.        Gasoline,

                                   III.        Gas oil,

                                  IV.        Diesel,

                                   V.        Lubricating oil,

                                  VI.        Grease,

                                 VII.        Vaseline

                               VIII.        paraffin wax.

NATURAL GAS

Is obtained by drilling deep holes which is known as oil wells, the gas obtained is transported in cylinders and pipelines.

Natural gas consists of methane (CHA) and small amount (proportion of Ethane CHo in Tanzania natural gas is obtained from songosongo)

Production of wood charcoal in rural area

Wood charcoal are made by burning wood in insufficient supply of air (destructive distillation of wood)

              I.        The trees are cut down into small pieces

            II.        The pieces are arranged in a pit closed contact with each other.

           III.        Then they are covered by soil material which limits air supply.

          IV.        Therefore the fire is set to burn pieces of woods.

           V.        After 3 or 4 days the pit is uncovered to get the charcoal. The charcoal obtained is a black light porous substance which absorb gas readily

Uses of wood charcoal

1. Used in gas masks to absorb any poisonous gases present in a particular area

2. Is the main domestic fuel in rural areas

Characteristic of good fuel

1. They should have high heat content i.e they must produce a lot of energy.

2. They must be cheap

3. They should have little or no product like ash and smoke

4. They must not give off dangerous by products like poisonous fumes

5. They should be easily stored and transported

6. The should be easily controlled

Categories of fuel

(1) Solid fuel

e.g. charcoal,

fire wood.

(11)Liquid fuel

 e.g. Kerosene,

 petrol.

(111)Gaseous fuel

e.g. Water gas

producer gas

SOLID FUELS.

Are obtained from trees and plants either directly as wood or as fossil remains of vegetable matter that were buried deep underground in post geological ages

Advantages

1. Are cheap

2.Are easily to obtain e.g. fire wood

Disadvantages

1. Require much space for storage

2.Leave smoke and ash on burning

 e.g.. fire wood

3.Low heat content.

LIQUID FUELS

Are obtained from petroleum

 e.g. Kerosene,

 diesel,

gasoline.

Advantages

1. They have no solid residue when they burnt

2. They require less storage space than solid fuels.

3. High heat content compared to solid

Disadvantages

      I.        Are more expensive than solid fuel.

II.     Are dangerous if not used in care.

GASES FUEL

These includes

 biogas,

coal gas,

 water gas,

 liquefied petroleum (LPG)

These fuel can flow through pipes.

Advantages

                      I.        Do not leave reduce on burning

                    II.        They have high heat content

Disadvantages

                      I.        Very expensive

                    II.        They are so dangerous if not used with care

Classification of fuel according to their efficiency

The efficient of a fuel explained in the form of the heat energy that can be produced when that fuel is completed. An efficient fuel is one which produce a lot of heat energy when a small amount of it is used and does not produce a lot of gaseous wastes into the environment Gaseous fuels are more sufficient followed by liquid fuel lastly solid fuel.

1^stGaseous fuel

e.g. Natural gases

2^nd Liquid fuel

e.g. kerosene

3^rd Solid fuel

e.g. Charcoal

CALORIFIC VALUE OF FUEL

Is the heat liberated on burning with mass of fuel.

 The calorific value is measured in colorimetric .

SI unit is kilojoules per kilogram (KJ/Kg) or kilojoules per grams.

A sample of fuel is weighed and burnt, the liberated heat used to heat a known mass of water and the rise in temperature of water gives an estimate of calorific value of fuel

Comparison of calorific value of some fuel

Experiment

Aim:

To determine the energy value of ethanol (alcohols). The experiment involves burning of mass of an alcohol. The heat produced when alcohol is burning known as mass of water.

The rise in temperature of water is recorded and the heat produced is calculated.

Materials:

 ethanol,

 water thermometer,

 small bottle,

 lamp,

trough.

PROCEDURES

1. Measure 250cm (250g) of water in measuring cylinder and pour it to thin metal can

2.Pour ethanol into small bottle fixed with cork and wick and find the mass of the simple lamp so formed (ie bottle+cork+wick)

3. Record temperature of the water.

4. Light the lamp and let it heat the water directly (do not use gauze) until the temperature rises about 30Ëšc.

5. Use a shield to protect the flame from drought.

6. Extinguish the flame and record the highest temperature of water

7. Find the mass of the lamp when it is cold (i.e Reweigh the lamp)

8. Stir the water during the heating

Report the following

Temperature of cold water=t₁

 Temperature of hot water = t₂

Mass of lamp at the begging =w₂(g)

Mass of the lamp at the end =w(g)

Specific heat capacity of water = 42

The heat gained by the water = specific heat capacity x mass x rise in term of premature

This is the energy value of ethanol. The results are much lower than an accurate value because some of the heat produced warm the can and the air so does not pass into the water.

Example

Calculate the heat obtained by burning ethanol using the information given:

USES OF FUEL

Fuels are used in different ways in daily life

              I.        To run machines in industries and motor vehicles e.g. petrol, diesel and coke

            II.        For cooking ,boiling and provision of warmth at home e.g. fire wood, kerosene, coal and coke

           III.        For drying for example tobacco leaves are dried in kilns by burning woods.

          IV.        For light at home especially rural areas where electricity is not available for example kerosene

THE ENVIRONMENT EFFECT ON USING CHARCOAL AND FIREWOOD AS SOURCE OF FUELS

Extensive harvest of plants /trees for fire wood and charcoal production would lead to environmenta effects such as deserts

Disadvantage of deforestation duel to fuel production

1. Leave the land bare to agents of erosion like moving water, animals and winds.

2. Affect the normal circulation of water that means effect water cycle.

3. Destruction of the home for wildlife and this destructs the ecosystem

CONTRIBUTION OF VEGETATION IN BALANCING ATMOSPHERIC GASES

1. Forests and other vegetation form a very important habitat for various kinds of wild animals and micro-species

2. They are also source of food and wood.

3. They attract the rain and help in balancing atmospheric gases.

4. The well conserved vegetation helps at keeping the balance of gases in the atmosphere and environmental pollution caused by gases.

NB;

In order to keep the balance gases recycling of the gases show be disrupted.

Example

Carbornidioxide is added to the atmosphere through respiration However, photosynthesis in plants remove the gas from the atmosphere as a result carbondioxide percentage the air stayed approximately constant, in this way gaseous pollution from motor vehicles, casual burning of substance and industry process is minimized.

ALTERNATIVE TO FIREWOOD AND CHARCOAL AS SOURCES OF FUEL

To avoid environmental hazard due to deforestation on alternative source of fuels must be encouraged

Renewable energy source:

 Are energy source that can be replaced by natural process; Are fuel source that cannot be replaced with time

Examples of renewable energy source are ;

              I.        Solar energy -energy from the sun

            II.        Geothermal - energy source that is deep inside the earth

           III.        Renewable energy source; Are energy source that can be replaced by natural process: Are fuel source that cannot be replaced with time

          IV.        Examples of renewable energy source are ;

           V.        Solar energy-energy from the sun

          VI.        Geothermal - energy source that is deep inside the earth

         VII.        Wind – is the energy of moving air

       VIII.        Ocean waves

          IX.        Tidal waves - is the energy of rising and falling tides

           X.        Biomass

          XI.        Hydroelectric energy

CONSERVATION OF ENERGY

- Energy

Is ability or capacity of doing work

- There are two kinds of the energy

(1)Potential energy

(11) Kinetic energy

POTENTIAL ENERGY;

Is the energy in matter due to its position (rest) or state Potential energy is stored in different forms eg.

 coal petroleum,

 natural gas,

elastic energy

 gravitation energy

Such energy does not do work as it is stored It is capable of doing work while when its changed to other form of energy e.g. heat light, e.t.c

KINETIC ENERGY:

Is the energy possessed by the body due to its motion.