Intensive Class Chemistry SPM

Intensive Class Chemistry SPM

What you need? • Module • Spot Questions • Intensive Class

9/12/2014

Prepared By Sir HONG BOON LIANG

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Sodium chloride, NaCl is an ionic compound while tetrachloromethane, CCl4 is a covalent compound. These compounds have different physical properties. Compare and explain the differences between the two compounds based on: • Melting point • Electrical conductivity [8 marks]

Module page 22 number 8 - The melting point of sodium chloride is high because the electrostatic forces between ions are strong. 1m + 1m - The melting point of tetrachloromethane is low because the Van Der Waals forces between molecules are weak. 1m + 1m - Sodium chloride can conduct electricity in molten state or aqueous solution because it has free moving ions. 1m + 1m - Tetrachloromethane cannot conduct electricity because it has molecules. 1m + 1m

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Carbon reacts with chlorine to form a covalent compound, tetrachloromethane. Describe how the bonds between carbon atom and chlorine atoms are formed. Proton number of C = 6, Cl = 17. [7 marks]

Module pages 21, 22 number 7 - The electron arrangement of carbon atom is 2.4. 1m - Carbon atom contributes 4 valence electrons for sharing to achieve an octet electron arrangement. 1m - The electron arrangement of chlorine atom is 2.8.7. 1m - Chlorine atom contributes 1 valence electron for sharing to achieve an octet electron arrangement. 1m - One carbon atom shares electrons with four chlorine atoms. 1m - Four single covalent bonds are formed. 1m - Drawing 1m

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Magnesium reacts with chlorine to form an ionic compound, magnesium chloride. Describe the formation of the compound. Proton number of Mg = 12, Cl = 17. [7 marks]

Module page 21 number 6 - The electron arrangement of magnesium atom is 2.8.2. 1m - Magnesium atom releases 2 valence electrons to form magnesium Ion. Magnesium ion achieves an octet electron arrangement. 1m - The electron arrangement of chlorine atom is 2.8.7. 1m - Chlorine atom receives 1 electron to form chloride ion. Chloride ion achieves an octet electron arrangement. 1m - One magnesium atom releases two valence electrons to two chlorine atoms. 1m - Strong electrostatic force pulls the magnesium ion and chloride ions together. 1m - Drawing 1m 4

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Explain the industrial preparation of sulphuric acid.

[10 marks]

Module pages 49, 50 spot questions number 13 - Sulphuric acid produced from contact process. 1m - Sulphur is burnt in air to produce sulphur dioxide. 1m - S + O2  SO2 1m - Sulphur dioxide is burnt in excess oxygen to produce sulphur trioxide with the presence of vanadium(V) oxide, 450 – 550 °C and pressure 1 atm. 1m + 1m - 2SO2 + O2  2SO3 1m - Sulphur trioxide is dissolved in concentrated sulphuric acid to produce oleum. 1m - SO3 + H2SO4  H2S2O7 1m - Oleum is dissolved in water to produce sulphuric acid. 1m - H2S2O7 + H2O  2H2SO4 1m 5

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Describe one laboratory experiment to study the effect of concentration on the rate of reaction. Your answer should include the following: • List of materials and apparatus • Procedure of the experiment • Sketch a graph to show the relationship between concentration and rate of reaction [12 marks]

• Materials - Sodium thiosulphate solution 0.5 mol dm-3 1m - Sulphuric acid 1.0 mol dm-3 1m • Apparatus - 100 cm3 measuring cylinder, 10 cm3 measuring cylinder, 250 cm3 conical flask, stopwatch, paper 1m • Procedure 1. Measure 50 cm3 of sodium thiosulphate solution using 100 cm3 measuring cylinder and poured into a conical flask. 1m 2. Place the conical flask on a piece of paper marked with ‘X’. 1m 3. Measure 5 cm3 of sulphuric acid using 10 cm3 measuring cylinder and add into the conical flask. 1m 4. Start the stopwatch quickly. 1m 6

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Describe one laboratory experiment to study the effect of concentration on the rate of reaction. Your answer should include the following: • List of materials and apparatus • Procedure of the experiment • Sketch a graph to show the relationship between concentration and rate of reaction [12 marks]

5. Stop the stopwatch when the ‘X’ mark disappear from sight. 6. Record the time taken. 7. Repeat steps 1 to 6 using different concentration of sodium thiosulphate solution. Chemical equation of the reaction Na2S2O3 + H2SO4  Na2SO4 + S + SO2 + H2O Concentration of Na2S2O3, mol dm-3

1 / time, s-1 1m

1m 1m 1m Max 5m

1m + 1m

1m + 7

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Neutralization reaction between acid and alkali can be used to produce soluble salt. By using a suitable acid and alkali, describe how you can prepare a pure sample of soluble salt by using neutralization reaction. [12 marks] Module pages 39, 40 number 9 - NaOH + HCl  NaCl + H2O 1m - 50 cm3 of 1.0 mol dm-3 sodium hydroxide solution is measured and poured into a conical flask. 1m - Add 3 drops of phenolphthalein indicator into the conical flask. 1m - Filled a burette with 1.0 mol dm-3 hydrochloric acid and record the initial reading of burette. 1m - Add the hydrochloric acid slowly into the conical flask until pink colour solution turns colourless and record the final reading of burette. 1m + 1m

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Neutralization reaction between acid and alkali can be used to produce soluble salt. By using a suitable acid and alkali, describe how you can prepare a pure sample of soluble salt by using neutralization reaction. [12 marks] - Repeat the experiment by adding the same volume of sodium hydroxide solution and hydrochloric acid without using phenolphthalein indicator to get pure salt. 1m + 1m - The mixture is then heated in a evaporating dish until saturated. 1m - The saturated solution is cooled to room temperature. 1m - White salt crystals, sodium chloride are filtered. 1m - White salt crystals are dried between filter papers. 1m

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You are given a sample of solid copper(II) nitrate salt. Describe a chemical test that can be used to verify the presence of copper(II) ions and nitrate ions in copper(II) nitrate salt. [8 marks]

Module pages 43, 44 • Test for copper(II) ion, Cu2+ - Solid of copper(II) nitrate salt is dissolved in water. 2 cm3 of copper(II) nitrate solution is poured into a test tube. 1m - Add a few drops of sodium hydroxide solution until excess into a test tube. 1m - Blue precipitate is formed. 1m - Blue precipitate insoluble in excess sodium hydroxide solution. 1m

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You are given a sample of solid copper(II) nitrate salt. Describe a chemical test that can be used to verify the presence of copper(II) ions and nitrate ions in copper(II) nitrate salt. [8 marks]

• Test for nitrate ion, NO3- 2 cm3 of copper(II) nitrate solution is poured into a test tube. Add 2 cm3 of dilute sulphuric acid into a test tube. 1m - Add 2 cm3 of iron(II) sulphate solution to the mixture. 1m - Add slowly concentrated sulphuric acid through the wall of the test tube. 1m - Brown ring is formed. 1m

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Describe the cleansing action of soap on the stained cloth.

[10 marks]

Module pages 88, 89 number 7 - Soap molecules dissolve in water and decrease the surface tension of water. 1m - Soap molecules increase the wetting ability of water. 1m - Soap molecules consist of hydrophilic and hydrophobic parts. 1m - Hydrophilic parts dissolve in water. 1m - Hydrophobic parts dissolve in grease. 1m - Scrubbing breaks the grease into small droplets. 1m - Droplets suspended in water to form an emulsion. 1m - Rinsing washes away the droplets. 1m 1m + 1m 12

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Describe two methods to verify the solution is an acid. In your answer, include example of an acid and chemical equation for the reactions involved. [10 marks]

Module page 10 number 9 (a) (d) Module page 34 number 11 • Acid reacts with reactive metal to produce salt and hydrogen gas.1m - 10 cm3 of 1.0 mol dm-3 hydrochloric acid is poured into a test tube. Add 2 g of zinc powder into a test tube. 1m - Place a lighted wooden splinter at the mouth of the test tube and ‘pop’ sound produced. 1m Chemical equation of the reaction Zn + 2HCl  ZnCl2 + H2 1m

1m +

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Describe two methods to verify the solution is an acid. In your answer, include example of an acid and chemical equation for the reactions involved. [10 marks]

• Acid reacts with metal carbonate to produce salt, carbon dioxide gas and water. 1m - 10 cm3 of 1.0 mol dm-3 hydrochloric acid is poured into another test tube. Add 2 g of calcium carbonate powder into a test tube. 1m - Pass through the gas released into lime water and lime water turns cloudy. 1m Chemical equation of the reaction CaCO3 + 2HCl  CaCl2 + CO2 + H2O 1m

1m +

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When going down group 1 in the Periodic Table, the reactivity of the metal increases from lithium to potassium. Explain. [4 marks]

Module page 16 number 12 (b) - The size of atom increases because the number of shell filled with electrons increase. 1m - Distance between nucleus and valence electron increases. 1m - Attractive forces between nucleus and valence electron become weaker. 1m - The tendency to release a valence electron to achieve the octet electron arrangement will be increases. 1m

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Explain why chlorine exists as diatomic molecule at room temperature. [4 marks]

Module pages 21, 22 number 7 - The electron arrangement of a chlorine atom is 2.8.7. 1m - A chlorine atom is unstable atom. 1m - The valence shell of a chlorine atom needs one electron to achieve an octet electron arrangement. 1m - Two chlorine atoms share one pair of electrons to form one single covalent bond. 1m

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Ammonia is manufactured in industry through Haber Process. Describe briefly Haber Process. [5 marks]

Module pages 49, 50 spot questions number 13 - Nitrogen gas and hydrogen gas are heated together according to the ratio one mole nitrogen gas to three moles hydrogen gas. 1m - The reaction at temperature of 450 °C and pressure of 200 atm. 1m - The reaction uses iron as catalyst. 1m Chemical equation of the reaction N2 + 3H2  2NH3

1m + 1m

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Metals react with oxygen gas to form a metal oxide. Plan one laboratory experiment to compare the reactivity of two named different metals when react with oxygen gas. Your answer should include the following: • Procedure of the experiment • Observations • A labelled diagram showing the apparatus set-up [12 marks]

• Procedure 1. Put one spatula of solid potassium manganate(VII) in a boiling tube. 1m 2. Put some glass wool into the boiling tube. 1m 3. Clamp the boiling tube horizontally. 1m 4. Place one spatula of magnesium powder on a piece of asbestos paper and put into the boiling tube. 1m 5. Heat the magnesium powder strongly. 1m 6. Then heat the solid potassium manganate(VII). 1m 7. Repeat the experiment using copper powder. 1m

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Metals react with oxygen gas to form a metal oxide. Plan one laboratory experiment to compare the reactivity of two named different metals when react with oxygen gas. Your answer should include the following: • Procedure of the experiment • Observations • A labelled diagram showing the apparatus set-up [12 marks]

• Observations - Magnesium powder burns brightly with a white flame. The white solid is formed. 1m - Copper powder glows dimly. The black solid is formed. 1m - Magnesium is more reactive than copper. 1m • Diagram 1m + 1m

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Describe a laboratory experiment to prepare an ester by using named alcohol and named carboxylic acid. Your answer should include the following: • A list of materials • Procedure of the experiment • Observation and chemical equation • Name of the ester produced [10 marks]

Module page 66 number 18 • Materials - Ethanol, ethanoic acid, concentrated sulphuric acid • Procedure 1. Pour 5 cm3 ethanol into a boiling tube and add 5 cm3 of ethanoic acid. 2. Add 3 drops of concentrated sulphuric acid into a boiling tube. 3. Heat the mixture carefully using a small flame. 4. Boil the mixture slowly about 3 minutes under reflux. 5. Pour the contents of the boiling tube into the beaker containing water and smell the contents of the beaker.

1m

1m 1m 1m 1m

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1m

Describe a laboratory experiment to prepare an ester by using named alcohol and named carboxylic acid. Your answer should include the following: • A list of materials • Procedure of the experiment • Observation and chemical equation • Name of the ester produced [10 marks]

• Observation - Fruity smell substance produced. Chemical equation of the reaction C2H5OH + CH3COOH  CH3COOC2H5 + H2O • Name of the ester Ethyl ethanoate

1m

1m + 1m

1m

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By using potassium iodide solution and a suitable oxidizing agent, describe a laboratory experiment of a redox reaction in U-tube. Your answer should include the following: • Half equations involved • Procedure of the experiment • Observations • A labelled diagram [10 marks]

Module page 77 number 15 • Half equations Electrode in potassium iodide solution / Anode 2I-  I2 + 2e 1m Electrode in bromine water / Cathode Br2 + 2e  2Br1m Overall ionic equation 2I- + Br2  I2 + 2Br1m • Procedure 1. Filled the U-tube with dilute sulphuric acid until 5 cm from the mouth of each arm. 1m 2. Add potassium iodide solution carefully to one arm and bromine 22 water to another http://www.facebook.com/Sir arm until 3 cm height. 1m HONG Chemistry Group

By using potassium iodide solution and a suitable oxidizing agent, describe a laboratory experiment of a redox reaction in U-tube. Your answer should include the following: • Half equations involved • Procedure of the experiment • Observations • A labelled diagram [10 marks]

3. Immersed the carbon electrodes to each arm and connect to the galvanometer using connecting wire. 1m 4. Record the observations. • Observations Electrode in potassium iodide solution / Anode - Colourless potassium iodide solution changes to purple. Electrode in bromine water / Cathode - Brown colour of bromine water changes to colourless. 1m

1m

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By using potassium iodide solution and a suitable oxidizing agent, describe a laboratory experiment of a redox reaction in U-tube. Your answer should include the following: • Half equations involved • Procedure of the experiment • Observations • A labelled diagram [10 marks]

• Diagram

1m + 1m

Carbon electrode

Potassium iodide solution

Carbon electrode

Bromine water

Dilute sulphuric acid

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Explain the observations at anode for the electrolysis of 1.0 mol dm-3 sodium chloride solution and 0.001 mol dm-3 sodium chloride solution using carbon electrodes. [8 marks]

Module page 27 number 12 (b) • 1.0 mol dm-3 sodium chloride solution - Chloride ions selected to discharge at anode. 1m - Concentration of chloride ions is higher than hydroxide ions. 1m - Greenish-yellow gas bubbles are released. 1m - The product is chlorine gas. 1m • 0.001 mol dm-3 sodium chloride solution - Hydroxide ions selected to discharge at anode. 1m - Hydroxide ions is lower than chloride ions in electrochemical series. 1m - Colourless gas bubbles are released. 1m - The product is oxygen gas. 1m 25

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Explain the observations at anode for the electrolysis of 1.0 mol dm-3 silver nitrate solution using two carbon electrodes and two silver plates. [8 marks] Module page 27 number 12 (c) • Carbon electrodes - Hydroxide ions selected to discharge at anode. 1m - Hydroxide ions is lower than nitrate ions in electrochemical series. 1m - Colourless gas bubbles are released. 1m - The product is oxygen gas. 1m • Silver plates - Silver plate dissolves in silver nitrate solution at anode. 1m - Silver plates are active electrodes which take part in chemical reaction. 1m - Silver plate at anode becomes thinner. 1m - The product is silver ion. 1m 26

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Describe an experiment that you can carry out in your school laboratory to determine the heat of combustion of ethanol. Your description should include precautionary steps and the steps involved in the calculation. [12 marks] Module pages 83, 84 number 12 (a) • Procedure and precautionary steps 1. Measure 200 cm3 of water and pour it into the copper can. 1m 2. Measure and record the initial temperature of the water. 1m 3. Fill the small lamp with ethanol then weigh it and record the initial mass. 1m 4. Light the wick of the lamp. 1m 5. Place the lamp as near as possible to the copper can. 1m 6. The apparatus is protected by a wind shield. 1m 7. Stir the water continuously. 1m 8. Blow out the flame when the temperature rises 10 °C to 30 °C and record the highest temperature of the water. 1m 27

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Describe an experiment that you can carry out in your school laboratory to determine the heat of combustion of ethanol. Your description should include precautionary steps and the steps involved in the calculation. [12 marks] 9. Weigh the lamp as quickly as possible and record the final mass. 1m Max 5m • Result Initial temperature of the water / °C = T1 Highest temperature of the water / °C = T2 Temperature rise of water / °C = T2 – T1 1m Initial mass of lamp + ethanol / g Final mass of lamp + ethanol / g Mass of ethanol that was burnt / g

= = =

m1 m2 m1 – m2

1m 28

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Describe an experiment that you can carry out in your school laboratory to determine the heat of combustion of ethanol. Your description should include precautionary steps and the steps involved in the calculation. [12 marks] • Calculation Heat released, Q 1m Number of moles of ethanol Heat of combustion, ΔH 1m • Diagram

= 200 g × 4.2 J g-1 °C-1 × (T2 – T1) °C = (m1 – m2) g / 46 g mol-1 1m = 200 g × 4.2 J g-1 °C-1 × (T2 – T1) °C (m1 – m2) g / 46 g mol-1 1m + 1m

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GOOD LUCK !!! A+ Chemistry Thank You

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