Physical Science 4ever: TEXT BOOK ACTIVITIES

ACTIVITY - 1

Aim: To find whether the given solutions are acidic or basic in nature

Materials Required: Hydrochloric acid (HCI), sulphuric acid (H₂SO₄), nitric acid (HNO₃), acetic acid (CH₃COOH), sodium hydroxide (NaOH), calcium hydroxide [Ca(OH)₂], potassium hydroxide (KOH), magnesium hydroxide [Mg(OH)₂], and ammonium hydroxide (NH₄OH).

Procedure:

· Collect the following samples from the science laboratory – hydrochloric acid (HCI) sulphuric acid (H₂SO₄), nitric acid (HNO₃), acetic acid (CH₃COOH), sodium hydroxide (NaOH), calcium hydroxide [Ca(OH)₂], potassium hydroxide (KOH), magnesium hydroxide [Mg(OH)₂], and ammonium hydroxide (NH₄OH).

· Put a drop of each of the above solutions on a watch glass and test with a drop of the following indicators as shown in the table.

Observations: After performing the activity we can observe the colour changes

	Sample solution	Red litmus paper	Blue litmus paper	Phenolphthalein Solution	Methyl Orange Solution
1.	HCl	Unchanged	Turns to red	Colourless	Changes to red
2.	H₂SO₄	Unchanged	Turns to red	Colourless	Changes to red
3.	HNO₃	Unchanged	Turns to red	Colourless	Changes to red
4.	CH₃COOH	Unchanged	Turns to red	Colourless	Changes to red
5.	NaOH	Turns to blue	Unchanged	Changes to pink	Changes to yellow
6.	KOH	Turns to blue	Unchanged	Changes to pink	Changes to yellow
7.	Mg(OH)₂	Turns to blue	Unchanged	Changes to pink	Changes to yellow
8.	NH₄OH	Turns to blue	Unchanged	Changes to pink	Changes to yellow
9.	Ca(OH)₂	Turns to blue	Unchanged	Changes to pink	Changes to yellow

Conclusion: These indicators tell us whether a substance is acidic or basic by change in colour.

ACTIVITY - 2

Aim: To test the given samples of acids and bases with the help of olfactory indicators.

Materials Required: Dilute hydrochloric acid, sodium hydroxide solution, onion juice, clove oil, dilute vanilla essence and test tubes.

Procedure:

· Take some finely chopped onions in a plastic bag along with some strips of clean cloth. Tie up the bag tightly and leave it overnight in the fridge. The cloth strips can now be used to test for acids and bases.

· Take two of these cloth strips and check their odour.

· Keep them on a clean surface and put a few drops of dilute HCI solution on one strip and few drops of dilute NaOH solution on the other.

· Rinse both cloth strips with water and again check their odour.

· Note your observations.

· Now take some dilute vanilla essence and clove oil and check their odour.

· Take some dilute HCI solution in one test tube and dilute HCI and dilute NaOH solutions and record your observation.

Observations:

In the above activity the following observations have been observed-

· Onion: Onion has a peculiar smell due to the presence of Sulphurous allium. The smell of onion diminishes in a base because it reacts like acid and remains as it is in acid.

· Vanilla essence: Vanilla is a weak acid so the odour of vanilla essence disappears when it is added to a base. The odour of vanilla essence persists when it is added to an acid.

· Clove Oil: In bases, its characteristic smell cannot be detected.

Conclusion: The olfactory indicators change the odour in acidic and basic mediums.

ACTIVITY - 3

Aim: To study the reaction of acids or bases with active metals.

Materials Required: Zinc granules, sulphuric acid, hydrochloric acid, acetic acid, sodium hydroxide, calcium hydroxide, test tube, test tube stand, delivery tube, soap, water, trough, cork and candle.

Procedure:

· Set the apparatus as shown in fig.

· Take about 2 ml of dilute sulphuric acid in a test tube and add a few pieces of zinc granules to it.

· Pass the gas being evolved through the soap solution.

· Take a burning candle near a gas-filled bubble.

· Repeat this activity with some more acids like HCI, HNO₃, and CH₃COOH.

Observation: When we bring a burning candle near a gas-filled bubble the gas burns with a popping sound.

Conclusion: Zinc metal displaces hydrogen from sulphuric acid.

Zn+ H₂SO₄ → ZnSO₄ +H₂↑

Bubbles come out vigorously with strong acids. Zinc also reacts with weak acids like acetic acid, but gas is formed slowly.

ACTIVITY - 4

Aim: To know the reaction between base and metal

Materials Required: A test tube, pieces of Zinc metal, sodium hydroxide solution, burner.

Procedure:

· Place a few pieces of granulated zinc metal in a test tube.

· Add 2 ml of sodium hydroxide solution and warm the contents of the test tube.

· Repeat the rest of the steps as in activity 2.3 and record your observation.

Observations:

1. Burning candle put off with pop sound and the evolved gas burns with blue flame. So, the evolved gas is Hydrogen (H₂). The gas burns with a blue flame and creates a popping sound.

2. Bases react with metals and give or liberate or evolve Hydrogen (H₂) gas.

Chemical reaction of the above activity:

2NaOH(aq) + Zn(s) → Na₂ZnO₂(aq) + H₂(g)

(Sodium zincate)

ACTIVITY - 5

Aim: To study the reaction of metal carbonates and bicarbonates with acids.

Materials Required: Two test tubes, 0.5 g of sodium carbonate (Na₂CO₃), 0.5 g of sodium hydrogen carbonate (NaHCO₃), Delivery tube, hydrochloric acid (HCl), lime water.

Procedure:

· Take two test tubes, and label them as A and B.

· Take about 0.5 g of sodium carbonate (Na₂CO₃) in test A and about 0.5 g of sodium hydrogen carbonate (NaHCO₃) in test tube B.

· Add about 2 ml of dilute HCI to both the test tubes.

· Pass the gas produced in each case through lime water (calcium hydroxide solution) as shown in figure and record your observations.

Observations:

Test Tube A- Na₂CO₃ + 2HCl →2NaCl + H₂O +CO₂

Test Tube B- NaHCO₃ + HCl → NaCl + H₂O +CO₂

On passing CO₂ gas through lime water it turns milky because insoluble white precipitate of CaCO₃ is formed as shown below:

Ca(OH)₂(aq) + CO₂(g) → CaCO₃(s) + H₂O(l)

On passing excess gas through lime water, it becomes colourless.

CaCO₃(s) + CO₂(g) → H₂O(I) → Ca(HCO₃)₂(aq)

Conclusion: All acids decompose metal carbonates and metal hydrogen carbonates with the liberation of CO₂ gas, water, and corresponding salt.

ACTIVITY - 6

Aim: To study the neutralisation reaction of an acid and a base.

Materials Required: Dilute sodium hydroxide solution, dilute hydrochloric acid, phenolphthalein, test tube, test tube stand and dropper.

Procedure:

1) Take some sodium hydroxide solution in a test tube and add a few (one or two) drops of phenolphthalein.

2) Observe the colour.

3) Now add hydrochloric acid drop by drop with the help of a dropper and observe the change.

Observation: When phenolphthalein is added to NaOH solution, the solution turns pink but colour disappears on adding a few drops of HCI to it.

NaOH + HCl → NaCl + H₂O

Conclusion: This experiment shows that the addition of HCI solution destroys the alkaline nature of NaOH. On the other hand, the addition of NaOH solution destroys the acidic nature of HCI, i.e., both NaOH and HCI appear to cancel the effect of each other.

ACTIVITY - 7

Aim: To study the reaction of metallic oxide with an acid.

Materials Required: Copper oxide, dilute hydrochloric acid, beaker and stirrer.

Procedure:

1) Take 1g of copper oxide in a beaker.

2) Now, add dilute acid such as dil. HCl to it with constant stirring.

3) Observe the change in the reaction mixture.

Observation: The colour of the solution becomes blue-green and the copper oxide dissolves.

Explanation & Conclusion:

· The blue-green colour of the solution is due to the formation of copper(II)chloride.

· Metal oxide ( here - CuO) reacts with an acid to produce salt and water, this is a neutralisation reaction.

· So metal oxides are basic in nature.

2HCI + CuO →CuCI₂ + H₂O

ACTIVITY - 8

Aim: To differentiate between the nature of ionic and covalent compounds on the basis of electrical conductivity.

Materials Required: Glucose, ethanol (ethyl alcohol), hydrochloric acid, sulphuric acid, beakers, wires, metal strips/nails (iron), rubber cork, one bulb, a 6 V battery and switch.

Procedure:

· Fix two nails on a cork and place the cork in a 100 ml beaker.

· Connect the nails to the two terminals of a 6-volt battery through a bulb and a switch, as shown in Figure.

· Now pour some dilute HCl in the beaker and switch on the current.

· As current flows through the solution, observe the bulb and record the observations.

· Repeat the same experiment using glucose, H₂SO₄ and ethyl alcohol solution.

Observation:

Solutions	Glucose solution	Ethanol	HCl solution	H₂SO₄ solution
Observation	Bulb does not glow	Bulb does not glow	Bulb glows	Bulb glows

Conclusion: Whether a solution will conduct electricity or not depends on the presence or absence of ions in it. As glucose and ethanol are covalent compounds, they do not conduct electricity but ionic compounds such as HCl and H₂SO₄ conduct electricity.

ACTIVITY - 9

Aim: To study the effect of dry and wet blue litmus paper on (i) dry HCl gas (ii) HCl solution. (OR) Experiment to prove acid produces (H⁺) ion in water.

Materials Required: Test tubes, NaCl salt, conc. H₂SO₄, dry and wet litmus paper strips, delivery tube and one cork.

Procedure:

1) Take about 1g solid NaCl in a clean and dry test tube.

2) Add a small amount of conc. H₂SO₄ to the test tube.

3) A gas is evolved. Test it with dry and wet litmus papers.

4) Record the observations.

Note: If the climate is very humid, the students should pass the gas produced through a guard tube (drying tube) containing calcium chloride to dry the gas.

Observation:

(i) Dry HCl gas

· Only the colour of wet (moist) blue litmus paper turns to red.

No change occurs in dry blue litmus paper.

(ii) HCl solution

· The colour of both wet and dry blue litmus papers turns to red.

Conclusion:

This experiment suggests that hydrogen ion in HCl are produced in the presence of water. The separation of H⁺ ion from HCl molecules cannot occur in the absence of water. As only colour of wet (moist) blue litmus paper changed to red, no change in colour occurs in dry litmus paper.

ACTIVITY - 10

Aim: To study the reaction of dissolution of concentrated sulphuric acid (or any other) with water.

Materials Required: Water, conc. H₂SO₄, beaker, thermometer, stand, test tube and glass rod.

Procedure:

1) Take water in a beaker.

2) Note the initial temperature with the help of a thermometer.

3) Take a small amount of conc. H₂SO₄ in a test tube and pour it drop by drop in the beaker (very slowly) along its sides.

4) Continue to stir the mixture with the help of a glass rod. Again note down the temperature.

Note: As the reaction is too vigorous, safety tips must be taken.

Observation: The temperature of the beaker rises in both cases.

Conclusion: Dissolution of conc. H₂SO₄in water is an exothermic reaction, as heat is evolved in the reaction.

ACTIVITY - 11

Aim: To determine the pH values of the given solutions with the help of pH paper.

Materials Required: Lemon juice, tomato juice, saliva, carrot juice, soda water, coffee, tea, tap water, 1 M NaOH solution, 1 M HCl solution and pH paper.

Procedure:

1) Take different solutions in different test tubes.

2) Now, place one or two drops of lemon juice on a pH paper strip.

3) Note the colour obtained.

Repeat the same procedure with each given solution using a new pH paper strip and note the colours obtained.

OObservations:

S. No	Solution	Colour of pH paper	Approximate pH value	Nature of substance
1	Saliva (before meal)	Light green	7.4	Base
2	Saliva (after meal)	Pale yellow	5.8	Acid
3	Lemon juice	Pink red	2.5	Acid
4	Colourless aerated drink	Pale yellow	6	Acid
5	Carrot juice	Light orange	4	Acid
6	Coffee	Orange yellow	5	Acid
7	Tomato juice	Dark orange	4.1	Acid
8	Tap water	Green	7	Neutral
9	1M NaOH	Dark blue, violet	13-14	Base
10	1M HCl	Red	1	Acid

Conclusion: Solutions having pH value less than 7 are acidic while those having pH value greater than 7 are basic in nature. As pH value of water is 7, therefore it is considered neither acidic nor basic but neutral.

ACTIVITY - 12

Aim: To test the soil pH for knowing the best soil for plants growth.

Materials Required: A test tube, water, soil

Procedure:

· Put about 2 g soil in a test tube and add 5 mL water to it.

· Shake the contents of the test tube.

· Filter the contents and collect the filtrate in a test tube.

· Check the pH of this filtrate with the help of universal indicator paper.

Observation:

pH of soil	Nature of soil	Effect on plant
7	Neutral	Grow well
<7	Acidic	Affected
>7	Basic	Affected

Conclusion: The best pH value range for soil is approximately 6 to 7 as this is the range in which most nutrients can be readily available.

ACTIVITY - 13

Aim: To write the formulae of the given salts and to identify the acids and bases from which the given salts may be obtained.

Materials Required: Potassium sulphate, sodium sulphate, calcium sulphate, magnesium sulphate, copper sulphate, sodium chloride, sodium nitrate, sodium carbonate and ammonium chloride.

Procedure:

· Write the formulae of the salts given below.

· Potassium sulphate, sodium sulphate, calcium sulphate, magnesium sulphate, copper sulphate, sodium chloride, sodium nitrate, sodium carbonate and ammonium chloride.

· Write the formulae of the given salts

· Identify the acids and bases from which the above salts may be obtained.

Observation & Conclusion:

S. No.	Salts	Formula	Family	Acid and Base
1.	Potassium sulphate	K₂SO₄	Potassium salts	H₂SO₄and KOH
2.	Sodium sulphate	Na₂SO₄	Sodium salts	H₂SO₄and NaOH
3.	Calcium sulphate	CaSO₄	Calcium salts	H₂SO₄and Ca(OH)₂
4.	Magnesium sulphate	MgSO₄	Magnesium salts	H₂SO₄and Mg(OH)₂
5.	Copper sulphate	CuSO₄	Copper salts	H₂SO₄and Cu(OH)₂
6.	Sodium chloride	NaCl	Chloride salts	HCl and NaOH
7.	Sodium nitrate	NaNO₃	Nitrate salts	HNO₃ and NaOH
8.	Sodium carbonate	Na₂Co₃	Carbonate salts	H₂CO₃ and NaOH
9.	Ammonium chloride	NH₄Cl	Chloride salts	HCl and NH₄OH

Aim: To determine (a) the pH value and nature (b) solubility of the given samples of salts.

Materials Required: Sodium chloride, potassium nitrate, aluminium chloride, zinc sulphate, copper sulphate, sodium acetate, sodium carbonate, sodium hydrogen carbonate, water, test tubes and pH paper.

Procedure:

Collect the following salt samples – sodium chloride, potassium nitrate, aluminium chloride, zinc suplhate, copper sulphate, sodium acetate, sodium carbonate and sodium hydrogen carbonate (some other salts available can also be taken).

(i) Make the solutions of the given salts in different test tubes by dissolving them in water.

(ii) Check their solubility in water (use distilled water only).

(iii) Check the action of these solutions on litmus paper and find the pH using a pH paper.

(iv) Note down, whether the salt is soluble or not; and if soluble, then up to what extent.

(v) Now, test all the solutions with the help of pH paper as in the activity 8 and record the observations.

Observations:

Sl. No	Salt	Formula	Solubility in water	Action on litmus	pH	Acid used	Base used
1	Sodium chloride	NaCI	soluble	no action	7	HCI	NaOH
2	Potassium nitrate	KNO₃	soluble	no action	7	HNO₃	KOH
3	Aluminium chloride	AICI₃	soluble	no action	<7	HCI	AI(OH)₃
4	Zinc sulphate	ZnSO₄	soluble	no action	<7	H₂SO₄	ZnO
5	Copper sulphate	CuSO₄	soluble	no action	<7	H₂SO₄	CuO
6	Sodium acetate	CH₃COONa	soluble	no action	>7	CH₃COOH	NaOH
7	Sodium carbonate	Na₂CO₃	soluble	no action	>7	H₂CO₃	NaOH
8	Sodium hydrogen	NaHCO₃	soluble	no action	>7	H₂CO₃	NaOH

Conclusion: This activity shows that nature of salt depends on its origin.

It means that salts have four categories:

(i) Salt of strong acid and strong base = Neutral (pH = 7).

(ii) Salt of weak acid and strong base = Basic (pH > 7).

(iii) Salt of strong acid and weak base = Acidic (pH < 7).

(iv ) Salt of weak acid and weak base = Neutral (pH = 7).

Aim: To observe water of crystallisation in copper sulphate crystals.

Materials Required:Boiling tube, test tube holder, copper sulphate crystals and Bunsen burner.

Procedure:

· Take about 2 g crystals of copper sulphate salt in a dry boiling tube and note the colour of crystals.

· Heat the boiling tube containing copper sulphate crystals and observe the changes occur.

· Some water droplets are formed in the boiling tube.

· Put off the burner after few minutes of heating. And add 2-3 drops of water in same sample.

· Observe the colour change after addition of 2-3 drops of water.

Observation:

· On heating blue crystals of copper sulphate, it becomes colourless or white and few drops of water are seen on test tube due to condensation of water of crystallisation.

· On adding few drops of water to heated anhydrous copper sulphate, the blue colour of copper sulphate reappears.

Conclusion: The blue colour of copper sulphate is due to the presence of water of crystallisation, which can be removed by heating.