04 Practical Revised Exploring Materials[1]

7/31/2019 04 Practical Revised Exploring Materials[1]

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PRACTICAL 1: FUEL

Aim: Investigating the fractional distillation of Petroleum

Materials/apparatus : Petroleum, anti-bumping granules (porcelain chips), filter paper, retort stand,thermometer (-10 360 C), distillation flask, Liebig condenser, conical flask, wire gauze, tripod

stand, evaporating dish and Bunsen burner.

Procedure:

A. Fractional distillation of Petroleum

1. Set up the apparatus as shown in Figure 1.

2. Heat slowly the petroleum in the distillation flask.

3. Collect the first fraction of petroleum at 30 80 C.

4. Continue the heating and collect the distillation in separate conical flasks at differentranges of temperature at 80 120 C, 120 160 C and 160 200 C.

B. Characteristics of the various fractions

5. Observe the colour of each fraction.6. Observe the viscosity of the fractions by tilting the conical flask.

7. For each of the fractions, pour some of it is into an evaporating dish and heat it. Observe the

colour of the flame and soot produced.

8. Record the observations.

Results:

Fraction Temperature

Range

Colour Viscosity Flammability

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Questions:

1. Discuss the flammability of the fractions of petroleum.

2. Discuss the relationship between the boiling point of the fractions with the:

a. colour of the fractionsb. viscosity of the fractions

c. the amount of soot produced by the fractions.

3. Fraction X has a formula of C6H14. Predict its colour, viscosity and the amount of soot producedby X.

4. Write a balanced chemical equation to represent the combustion of gasoline (C 8H18).

5. The incomplete combustion of gasoline results in emission of poisonous gasses such as carbon

monoxide and nitric oxide. Write a balanced chemical equation to represent the incompletecombustion of gasoline (C8H18).

6. What is biodiesel?

7. What are the advantages of using biodiesel compared to petroleum fuel?

Thermometer

Water out

Water in

Liebig

condenser

Petroleum

Porcelain chips

Distillationflask

Distillate

Figure 1: Set-up of Fractional distillation

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Combustion of alkanes- Alkanes do not react with air at room temperature but if heated, they burn

readily to give carbon dioxide and water in an exothermic reaction.

3

e.g CH4 + 2 O2 CO2 + 2 H2O

C4H10(g)+ 6O2(g) 4CO2(g) + 5H2O(g)

mplete combustion forming carbon monoxide

h less O2:

H4 + 3 O2 2 CO + 4 H2O

h even less O2:

4 + O2 C + 2 H2O


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PRACTICAL 2: ALLOY

Aim: To compare the rate of rusting of iron, steel and stainless steel

Materials/apparatus : Iron nail, steel nail, stainless steel nail, jelly solution, potasium hexacyanoferrate(III)

solution, water, sand paper, test tube, test tube rack.

Procedure:

1. Rub the nails using sand paper to remove the rust from the surface of the nails.

2. Place the iron nail in test tube A, the steel nail in test tube B and the stainless steel nail

in test tube C.

3. Prepare a 5% jelly solution by adding 5g of jelly into 100 cm

3

of boiling water.Then, add a fewdrops of potasium hexacyanoferrate(III) solution the jelly solution (Figure 1).

4. Pour the hot jelly solution into the three test tubes until all the nails are fully immersed.5. Place the test tube in a test tube rack and leave aside for five days. Observe the intensity of the

blue colour.

6. Record all observation in the table below.

Results:

Test tube Intensity of blue colour Inference

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Figure 1: Comparing the rate of rusting of iron, steel and stainless steel

Questions:

1. Explain the function of potasium hexacyanoferrate (III) solution.2. What is the relationship between the intensity of blue colour and the rate of rusting?3. Explain how the use of solidified jelly solution can improve the observation of the experiment.

4. Name the constituents of steel and stainless steel.

5. Based on the inference of investigation results, compare the rate of rusting of iron, steel andstainless steel and explain the inference.

6. How is the arrangement of atoms in a metal associated to its ductility and malleability?

7. Explain the difference between substitution alloy and interstitial alloy.

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To compare the rate of rusting of iron, steel and stainless steel

You have learnt that steel is an alloy of ____________. Steel is harder than _____________. Bothiron and steel can rust when exposed to _________and___________. Do they rust at the same rate?

Problem statement

How does the rate of rusting between iron, steel and stainless steel differ?

Hypothesis

______________________________________________________________________________

______________________________________________________________________________

Variables:

1. Manipulated variable (independent variables) : ___________________________________

(Which thing will you change?)

2. Responding variable (dependant variables): ______________________________________

(What will you measure?)

3. Fixed variable (control variables):______________________________________________(What things should you keep the same?)

Operational definition for rusting

____________________________________________________________________________

____________________________________________________________________________

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PRACTICAL 3: ALCOHOL, ETHER AND AMINES

Aim: To prepare samples of ethanol and to investigate the chemical properties of ethanol

Materials/apparatus : Glucose, cooked potatoes, mashed pineapple, rice, tapioca, mashed banana, yeast,Lime water, distilled water, tap water, potassium dichromate (VI) solution, concentrated sulphuric acid,

filter paper, conical flask, beaker, measuring cylinder, distillation flask, stopper with delivery tube, stopper

with one hole, thermometer, Liebig condenser, fractioning column, retort stands and clamps, tripod stand,

wire gauze, Bunsen burner, rubber tubing, filter funnel, boiling tube, blue litmus paper, evaporating dish,test tube holder, dropper, forceps.

Procedure:

A. To prepare samples of ethanol

1. Dissolve approximately about 20 g of glucose in 150 cm3 of distilled water in a

clean conical flask.

2. Add approximately about 10 g of yeast to the mixture and shake the mixture well.3. Close the conical flask with a stopper connected to a delivery tube. Dip the other end of the

delivery tube into lime water in a boiling tube as shown in Figure1(a) .

4. Leave the apparatus in a warm place (35 C) for about 4-5 days.

5. For time to time, observe any changes taking place.6. After about 4-5 days, filter the contents of the conical flask. Pour the filtrate into a

distillation flask.

7. Set up the apparatus for distillation as shown in Figure 1(b).8. Heat the filtrate in water bath and collect the ethanol that boils over at 78 to 80 C.

9. Examine the colour and the smell of the distillate collected.

10. Repeat steps 1 to 9 using cooked potatoes, mashed pineapple, rice, tapioca or mashedbanana to replace glucose.

B. To investigate the chemical properties of ethanol

B-1 To investigate the combustion of ethanol

Procedure:

1. Pour about 2 cm3 of the prepared ethanol into an evaporating dish.

2. Use a lighted wooden splinter to ignite the ethanol (Figure 2).

3. Note the combustibility of ethanol.

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Results:

B-1Test Observation

Combustibility

Colour of flame

Sootiness of flame

B-2 To investigate the oxidation of ethanol

1. Pour about 10 cm3 of potassium permanganate solution into a boiling tube.2. Add about 10 drops of concentrated sulphuric acid into the boiling tube using a dropper.

3. Add about 3 cm3 of ethanol to the mixture.

4. Set up apparatus as shown in Figure 3.5. Heat carefully the boiling tube with a gentle flame until the mixture boils.

6. Smell the product.

Questions:

1. Name the enzyme present in yeast that decomposes glucose into ethanol.

2. Write a balanced chemical equation to represent the decomposition of glucose into ethanol.3. Explain the use of fractional distillation in this experiment.

4. Write a balanced chemical equation to represent the combustion of ethanol.

5. What is the function of potassium permanganate solution in this experiment?

6. Write a balanced chemical equation to represent the oxidation of ethanol.7. Predict your observation when apparatus set-up in Figure 1 is left for more than a week.

Explain your answer.8. Can ethanol be used as vehicle fuel? Explain your answer.

Glucose + yeast

Lime water

Boi l ing tube

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Fermentationproduct

Cool water

Water bath

Figure 1(a): Preparation of ethanol Figure 1(b): Set-up for distillation of ethanol

Lighted wooden splinter

EthanolEvaporating dish

Figure 2: Combustion of ethanol

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Figure 3: Oxidation of ethanol

PRACTICAL 4: CARBOXYLIC ACIDS, ESTERS AND AMIDES

Aim: To prepare a sample of ester and to investigate the physical properties of ester.

Materials/apparatus : absolute ethanol, glacial ethanoic acid, concentrated sulphuric acid, 5% aqueoussodium bicarbonate solution, oil, water, sodium chloride solution, beaker, distillation flask, tap funnel,

round bottomed flask, conical flask, measuring cylinder, thermometer, Liebig condenser, Bunsen burner,

retort stands and clamps, tripod stand, stopper with two holes, wooden block.

Procedure:

A. To investigate the physical properties of ester

1. About 2 cm3 of ethyl ethanoate is poured into a test tube. The smell of the ester is noted.

2. About 5 cm3 of distilled water is added to the ester and the mixture is shaken well. The solubility of

the ester in water is noted.

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Acidified

potassium

permanganate

+ ethanol water bath


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3. Steps 1 to 2 are repeated using acetone and methylated spirits consecutively to replace distilled water.

Results:

Solvent ObservationWater

Acetone

Methylated spirits

B. To prepare a sample of ester

1. Mix about 50 cm3 of absolute ethanol with 50 cm3 of glacial ethanoic acid flask into a 250 ml

round-bottomed flask.2. Add carefully 10 cm3 of concentrated sulphuric acid to the content of the flask while swirling.

Add several boiling chips to the mixture.

3. Set up the apparatus as shown in Figure 1.

4. Heat the mixture under reflux for 1 hour.5. Remove the heating source and allow the mixture to cool to room temperature.

6. Pour the cooled mixture into a separatory funnel and add 25 cm3 cold water. Shake the separatory

funnel.7. Separate the lower aqueous layer from the upper organic layer. Discard the aqueous layer.

8. Add 25 cm3 5% aqueous sodium bicarbonate solution and shake the separatory funnel and discard the

lower layer.

9. Repeat procedure 8.10. Add 25 cm3 ofwater and shake the separatory funnel. Discard the aqueous layer

11. Add 5 cm3 of saturated aqueous calcium chloride. Stir the mixture gently and discard the aqueouslayer.

12. Observe the organic layer and smell it.

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oil bath

Ethanol + Ethanoic acid

+ Sulphuric acid

Figure 1: Preparation of ester

Questions:

1. Explain the meaning of esterification reaction.

2. Write a balanced chemical equation to represent the reaction between ethanoic acid and ethanol.

3. What is the function of concentrated sulphuric acid in this experiment?4. Explain another method of preparing ethyl ethanoat.

5. What is the function of 5% aqueous sodium bicarbonate solution in this experiment?

6. Explain the use of calcium chloride solution in this experiment.7. Compare the solubility of ethyl ethanoate in water, acetone and methylated spirits. Explain your

observation.

8. Name the ester produced from an esterification reaction between butanoic acid and ethanol.

9. Write a balanced chemical equation to represent the reaction above.

PRACTICAL 5: AMMONIA, SULPHURIC ACID AND NITRIC ACID

Aim: To prepare ammonium salt fertilizer.

Materials/apparatus : Ammonia solution (2M), dilute sulphuric acid (1M), beaker, glass rod, Bunsen

burner, tripod stand, wire gauze, filter funnel and filter.

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water bath

Water in

Water out


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Procedure:

1. Pour 30 cm3 of dilute sulphuric acid into a beaker.2. Add the ammonia solution little by little into the beaker while stirring the solution.

3. Do not add any ammonia solution when the solution smells amniotic.

4. Heat the solution until it becomes 1/3 of the original volume.5. Cool the solution is cooled in a mixture of ice and water. Filter the salt crystals produced using

the filter funnel and filter paper.

Questions:

1. Write a balance equation to represent the formation of ammonium sulphate in this

experiment.2. How does the addition of ammonium sulphate affects the pH of the soil?

3. Besides fertilizers, ammonium sulphate is also used as an agriculture spray adjuvant

for water soluble pesticides. Explain the function of ammonium sulphate in this area.

4. Name three examples of natural fertilizers which are used in farming.5. Name three examples of synthetic fertilizers which are used in agriculture.

6. Write chemical equations to represent the formation of:a. ammonium phosphate

b. ammonium nitrate

c. urea7. Calculate the percentage of nitrogen in 1 mole of the above fertilizers.

[ Relative atomic mass: H, 1; C,12; N,14; O, 16; P, 31; S, 32 ]

8. Which of the above fertilizer is the most suitable for the growth of plants? Explain

your answer.

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Figure: Preparation of ammonium salt fertilizer

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SOAPS AND DETERGENTS

The soap can prepared in the lab using the saponification process.

It is really soap but is different from the soap that you buy in shops. Why it different?

Saponification of fats and oils is the most widely used soap-making.

Soap is prepared by heating a mixture of a vegetable oil with concentrated sodium hydroxide

solution. The oils are first hydrolyzed to form glycerol and fatty acids.

The fatty acids then react with sodium hydroxide solution to produce soap.

The soap formed can be precipitated by adding sodium chloride.

The soaps are then rinsed with water to remove the glycerol and excess sodium hydroxide

The soap and detergent would be justified base on the following criteria:

i. biodegradable

ii. raw materials that are easily available

iii. additives that are environment friendly

iv. washing properties/ effective cleansing actionv. basicity

vi. other special features such as fragrance. Colour, etc

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PRACTICAL 6: SOAPS AND DETERGENTS

Aim: To prepare soap using the saponification process.

Materials/apparatus : Palm oil, sodium hydroxide solution, sodium chloride powder, filter paper, distilled

water, beaker, measuring cylinder, spatula, glass rod, filter funnel, wire gauze, tripod stand, Bunsen burner,

test tube

Procedure:

1. Pour 10 cm3 of palm oil into a beaker.

2. Add 50 cm3 of 5 mol dm-3 sodium hydroxide solution to the palm oil.3. Heat the mixture until it boils.

4. Stir the mixture with a glass rod.

5. Allow the mixture to boil for 10 minutes.

6. Remove the beaker from the heat. 50 cm

3

of distilled water and add three spatulaful of sodiumchloride to the mixture.

7. Boil the mixture for another 5 minutes.8. Allow the mixture to cool.

9. Filter out the soap. Wash the soap with a little distilled water.

10. Press the soap between a piece of filter paper to dry it.11. Feel the soap with your fingers. Place a small amount of the soap in a test tube. Add tap water

into the test tube. Shake the mixture.

12. Record the observations.

Questions:

1. Describe the properties of soap produced.

2. What is the function of sodium chloride in this experiment?

3. Write a word equation for the saponification process involved in this experiment.4. Predict your observation if tap water is replaced by distilled water in procedure 11.

Explain

your answer.

5. Can soap be produced by hydrolyzing fats or oils under acidic conditions? Explain youranswer.

6. Name two different techniques used in making soap.

7. What are the disadvantages of commercial soap?8. What are the materials used in the industry to manufacture detergent?

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04 Practical Revised Exploring Materials[1]