Three elements of group 1 in the Periodic Table

(1)

1 PERIODIC TABLE OF ELEMENTS

1. Using the suitable apparatus and materials, you are required to design a laboratory experiment to investigate / determine the reactivity of above mentioned elements when

they react with water. Statement of problem:

How does the reactivity of lithium, sodium and potassium/group 1 elements change when they react with water?

Variables:

Manipulated variable : Different types of alkali metals // Lithium, sodium, potassium Responding variable : Reactivity of alkali metals with water

Constant variable : Size of alkali metals, water

Hypothesis:

When going down Group 1, the reactivity of the metals with water increases.

Lists of substances and apparatus

Lithium, sodium, potassium, water, small knife, forcep, basin, filter paper

Apparatus and material Procedure:

1. Fill a basin / trough with water

2. Cut a small piece of lithium using a knife and forceps 3. Dry the oil on the surface of the lithium with filter paper 4. Place the lithium slowly onto water surface in a basin / trough 5. Record your observations

6. Repeat steps 1 – 5 using sodium and potassium to replace lithium one by one

Tabulation of data:

Alkali Metals Observations Lithium

Sodium Potassium

Three elements of group 1 in the Periodic Table Lithium Sodium Potassium

(2)

2

2. Chlorine and bromine show similar chemical properties but differ the reactivity. By using a suitable reaction, plan an experiment to compare the reactivity of these elements.

Problem statement:

How does the reactivity of chlorine and bromine differ when they react with hot iron wool?

Variable:

Manipulated: Type of halogens // chlorine and bromine Responding: reactivity of reaction (towards hot iron wool) Fixed: iron wool

Hypothesis:

Chlorine is more reactive than bromine towards hot iron.

Apparatus and substances:

boiling tube, delivery tubes, Bunsen burner, retort stand and clamp, stoppers Chlorine gas, liquid bromine, iron wool, soda lime

Procedure:

1. Clamp combustion tube horizontally to the retort stand. 2. Place iron wool in the middle of the combustion tube. 3. Heat the iron wool in the combustion tube strongly.

4. Pass through chlorine gas over the hot iron wool until no further change occur. 5. The excess chlorine gas is absorbed by soda lime.

6. Record the observation.

7. Repeat the experiment by using bromine.

Tabulation of data

Halogens Observation

Chlorine gas Liquid bromine

(3)

3

3. Oxides can be classified into basic oxide, acidic oxide and amphoteric oxide. An oxide that dissolves in acid only is a basic oxide. An oxide that dissolves in alkali only is an acid oxide. An oxide that dissolves in both acid and alkali is an amphoteric oxide.

Plan a laboratory experiment to study the properties // acid-base properties of oxides of elements in Period 3.

How does the acid-base properties // pH values of oxides of elements change across Period 3?

Hypothesis:

An acidic property of the oxides of elements increases where as basic properties of the oxides of elements decrease across period 3 // The oxides change from basic to amphoteric then to acidic across Period 3

Variables :

Manipulated : oxides of element of Period 3

Responding variables: pH values in water // solubility in acid or alkali

Fixed : water // universal indicator // pH meter // nictric acid // sodium hydroxide solution

Apparatus :

Test tube, test tube rack, gas jar, gas jar cover, 100 cm3 measuring cylinder.

Material:

Sodium oxide, magnesium oxide, aluminium oxide, silicon (IV) oxide, phosphorus

pentoxide, sulphur dioxide gas, 1.0 mol dm-3 nictric acid and 1.0 mol dm-3 sodium hydroxide solution and universal indicator.

Procedure:

1. A small piece of sodium oxide is put into a test tube half filled with distilled water. 2. The mixture is shaken.

3. Three drop of universal indicator are added to the mixture using dropper // pH meter is dipped into the mixture.

4. The colour of the mixture is observed and the pH value is recorded. 5. The procedure is repeated for the other oxides.

(4)

4 (a) Procedure:

1. A little / 0.5 g // half spatula R2O3 powder is put into two separate test tubes. 2. 5 cm3 of 1.0 mol dm-3 sodium hydroxide solution is added into the first test tube. 3. 5 cm3 of 1.0 mol dm-3 nitric acid is added into the second test tube.

4. Both test tubes are heated slowly. 5. Repeat step 1-4 for MO and TO2. 6. Record the observations.

(b) Variables:

manipulated: oxide R2O3, MO and TO2 Responding : acid-base properties

Fixed : sodium hydroxide solution, nitric acid (c) R2O3 – amphoteric oxide

MO – basic oxide TO2 – Acidic oxide (d) M, R, T

(5)

5

ELECTROCHEMISTRY

4. The displacement reaction is a chemical change which takes place when a metal placed higher in the electrochemical series displaces a metal below it from its salt solution.

Iron displaces copper from its salt solution because it is placed higher than copper in the electrochemical series. Based on this principle, plan a laboratory to construct the

electrochemical series.

How to construct the electrochemical series of metals based on the displacement of metals?

Hypothesis:

The greater the number of metals that can be displaced by a metal from their solutions, the higher is its position in the electrochemical series.

Variables :

Manipulated : pair of metal and salts solution used

Responding : the number of displacement reactions occurred fixed : concentration and volume of solution.

Apparatus: test tube, test tube rack

Materials: 1 mol dm-3 of magnesium nitrate, zinc nitrate, lead(II)nitrate, copper(II)nitrate solution. Magnesium, zinc, lead, and copper strip.

Procedure:

1. Pour 5 cm3 1 mol dm-3 of magnesium nitrate, zinc nitrate, lead(II)nitrate, copper(II)nitrate solution solutions into four separate test tubes.

2. Place a strip of magnesium ribbon into each test tube. 3. Record the observation.

4. Repeat step 1-3 using zinc, lead and copper to replace the magnesium strip. For each repetition, use a fresh salt solution.

5. Record all observations.

Tabulation Data: solution salt Metal Magnesium nitrate

Zinc nitrate Lead(II) nitrate Copper(II) nitrate

Mg Zn Pb Cu

(6)

6

5. The concentration of the electrolyte will affect the products formed at the electrodes

during electrolysis.

By using different concentration of sodium chloride solution, design an experiment to investigate the above statement.

How does the concentration of the electrolyte (sodium chloride solution) will affect the products formed at the anode electrode during electrolysis?

Variable:

Manipulated: concentration of the electrolyte (sodium chloride solution) Responding: products formed at the anode

Fixed: carbon electrodes, sodium chloride solution, blue litmus paper Hypothesis:

When concentrated sodium chloride solution is used, greenish yellow gas released at the anode, when diluted sodium chloride solution is used, colourless gas released at the anode.

Apparatus and Substances:

Carbon rods, electrolytic cell, battery, ammeter, connecting wires, test tubes

1.0 mol dm-3 sodium chloride solution, 0.0001 mol dm-3 sodium chloride solution, litmus paper

Procedure:

1. Half filled the electrolytic cell/beaker with 1.0 mol dm-3 sodium chloride solution. 2. A test tube filled with 1.0 mol dm-3 sodium chloride solution is inverted over the

anode carbon electrode.

3. Both electrodes are connected to the batteries using connecting wires//Complete the circuit

4. Record the observations at the anode.

5. Repeat step 1-4 by using 0.0001 mol dm-3 sodium chloride solution. (f) Tabulation of data:

Concentration electrolyte / sodium chloride solution

Observation at anode // Product at anode 1.0 mol dm-3

(7)

7

SALTS

Garden snail

6. The soft body of the garden snail is protected by its cone-shaped shell. What kind of chemical compound found in the shell to give it its hardness and waterproof nature? Actually the above mentioned shell consists of calcium carbonate, CaCO3. It is an insoluble salt. Referring to the situation above, plan a laboratory experiment to compare the solubility of

nitrate, sulphate, carbonate and chloride salt in water. Sample answer:

How does solubility of nitrate, sulphate, carbonate and chloride salt in water? // Does all nitrate, sulphate, carbonate and chloride salt soluble in water?

Variables:

Manipulated: nitrate, sulphate, carbonate and chloride salt // Type of salts Responding: solubility of salt

Fixed: volume and temperature of water // quantity of salt powder

Hypothesis:

Some of salts soluble in water but other salts insoluble in water // Some of salts soluble in water, while some are not.

Material:

Any suitable nitrate, sulpahte, chloride and carbonate salts soluble and insoluble in water distilled water.

Apparatus:

Test tube, test tube rack and spatula.

Procedure:

1. Half spatula of zinc nitrate powder is put into a test tube. 2. Pour 5 cm3 of distilled water into the test tube.

3. Stir the mixture / shake the test tube 4. Observe and record the solubility of salt.

5. Repeat step 1 to 4 by using various salt powder.

Salt Solubility in water / observation Zinc nitrate Calcium sulphate Potassium carbonate Lead(II)chloride Magnesium chloride Copper(II) carbonate Copper (II)sulphate

(8)

8

CARBON COMPOUNDS

7.

Aim : To compare / investigate the strength of vulcanised and unvulcanised rubber Problem statement:

How does the strength of vulcanised rubber differ from unvulcanised rubber?

Hypothesis:

Vulcanised rubber is stronger than unvulcanised rubber.

Variable:

Manipulated : vulcanised rubber and unvulcanised rubber

Responding : change in length of the rubber strip

Fixed : mass of weight, size of rubber strips

Material and apparatus:

Retort stand with clamp, bulldog clip, meter ruler, weight (20-50 g), vulcanised and unvulcanised rubber strips.

Procedure:

1. Hang a strip of vulcanised rubber to the retort stand with clip / bulldog clip. 2. Measure and record the initial length of the rubber strip with meter ruler. 3. Hang 50 g weight to the bottom end of the rubber strip using clip / bulldog clip. 4. Measure and record the length of the rubber strips.

5. Repeat step 1-4 replacing vulcanised rubber with unvulcanised rubber.

Result / Data

Type of rubber Initial length , cm Final length , cm vulcanised

(9)

9

8. Diagram shows two reagent bottles containing two colourless liquid of carbon compounds P and Q respectively.

P Q These two liquid are hexene and ethanioc acid.

Using suitable reagent, plan a laboratory experiment to identify the colourless liquid.

How to determine and identify hexane and ethanoic acid (liquid P and liquid Q?

Variables:

Manipulated variable: Hexene and ethanoic acid // Liquid P and Q Responding variable: Colour change of reagent // gas bubbles release

Constant variable: Volume of hexene and ethanoic acid // acidified potassium manganate(VII) // magnesium ribbon// zinc powder // calcium carbonate

Hypothesis

If liquid P decolourised purple colour of acidified potassium manganate(VII), so liquid P is hexene // Acid will produce gas bubbles with Magnesium (Calcium carbonate)

Apparatus

Test tube, dropper, and stopper

Materials

Liquid P, Liquid Q, acidified potassium manganate(VII) solution / Magnesium ribbon, zinc power or calcium carbonate chips)

Procedure:

1. 2 cm3 liquid P and liquid Q are poured into two different test tubes.

2. Three d r o p s o f a c i d i f i e d p o t a s s i u m m a n g a n a t e (VII) are added into the test tubes // a piece of magnesium ribbon are dipped into the test tubes. 3. The test tubes are closed with stoppers.

4. The mixtures are shaken. 5. The observations are recorded.

Liquid Observation P

(10)

10

RATE OF REACTION

Referring to the situation above, plan a laboratory experiment to investigate the effect of

concentration or catalyst on the rate of reaction between a named acid and a named metal.

9.

(i) Problem statement:

Does the higher the concentration of acid , the higher the rate of reaction?

Variables:

Manipulated variable : Concentration of acid Responding variable : Rate of reaction

Constant variable : Volume of acid //mass of metal Hypothesis:

The higher the concentration of acid, the higher the rate of reaction.

Materials

Zinc, (hydrochloric acid) [0.5 – 2.0] mol dm-3 , distilled water

Apparatus

Conical flask, measuring cylinder, stopper, delivery tube, basin, retort stand, burette, and stopwatch.

Procedure:

1. A burette is filled with water and inverted into a basin of water. The initial burette reading is recorded

2. (50-100) cm3 of acid [0.5 – 2.0] mol dm-3 acid is measured and poured into a conical flask.

3. 2 g of zinc powder is added into conical flask 4. The conical flask is closed immediately. 5. At the same time, the stopwatch is started.

6. The burette readings at intervals of 30 seconds are recorded until reaction stops. 7. The experiment is repeated using the same volume of acid with different

concentration.

Time(s) 0 30 60 90 120 150 180 210 240 270 300 Burette

Reading(cm3)

(11)

11

10.

(ii) Problem statement:

Does the presence of catalyst, copper(II) sulphate, increase the rate of reaction?

Variable:

Manipulated variable : Catalyst // copper(II) sulphate Responding variable : Rate of reaction

Constant variable : Volume and concentration of acid // mass of metal Hypothesis:

The presence of catalyst, copper(II) sulphate , increase the rate of reaction.

Materials

Zinc powder, copper(II)sulphate solution, water, hydrochloric acid [0.5 – 1.0] mol dm-3

Apparatus

Conical flask cm3, measuring cylinder, stopper with delivery tube, basin, retort stand, burette, stopwatch.

Procedure

1. A burette is filled with water and inverted into a basin of water. The initial burette reading is recorded

2. (50-100) cm3 of acid [0.5 – 1.0] mol dm-3 acid is measured and poured into a conical flask.

3. 5 cm3 of acid 0.5 mol dm-3 copper(II)sulphate solution is added into conical flask 4. 2 g of zinc powder is added into conical flask

5. The conical flask is closed immediately. 6. At the same time, the stopwatch is started..

7. The burette readings at intervals of 30 seconds are recorded until reaction stops. 8. The experiment is repeated without adding copper(II) sulphate solution

Time(s) 0 30 60 90 120 150 180 210 240 270 300 Burette

Reading(cm3) Volume of gas(cm3)

(12)

12

Neutralization in our daily lives

Agriculture Powdered lime (CaO) , limestone (CaCO3), ashes of burnt wood Used to treat acidic soil.

Industries 1. Powdered lime (CaO)

Used to treat acidic effluent from factories, acidic gas SO2 emitted by power station and industries.

2.Ammonia prevent the coagulation of latex by neutralizing the acid produced by bacteria in the latex.

Health 1. Anti-acids contain bases such as aluminium hydroxide and magnesium hydroxide to neutralize the excess acid in the stomach.

2. Vinegar (citric acid) is used to cure wasp stings that are alkaline in nature. 3. Baking powder (NaHCO3) is used to cure bee stings and ant bites that are acidic in nature.

4. Toothpaste contains bases that neutralize the acid produces by bacteria in our mouth.

(13)

13

(14)

14

Aim:

To investigate the reactivity of magnesium, copper, zinc and lead with oxygen

Variable:

manipulated: magnesium, copper, zinc and lead responding: reactivity with oxygen

Fixed : solid potassium manganate(VII)

Hypothesis:

The higher the position of metal in reactivity series, the higher the reactivity of metal with oxygen.

Apparatus:

Boiling tube, retort stand and clamp, Bunsen burner, spatula and forceps

Material:

Magnesium, copper, zinc and lead powder, solid potassium manganate(VII), asbestos paper.

Procedure:

1. Put one spatula of potassium manganate(VII), KMnO4 , into a boiling tube. 2. Push some glass wool into the boiling tube and clamp horizontally.

3. Place one spatula magnesium powder on a piece of asbestos paper and put into the boiling tube.

4. Heat magnesium powder strongly and then heat the solid KMnO4.

5. Observe and record how vigorous the reaction and colour of the residue when it is hot and when it is cold.

6. Repeat step 1 to 5 using copper, lead and zinc powder

Metal Vigour of reaction

Magnesium Copper Lead Zinc

(15)

15