SCIENCE (52) CHEMISTRY SCIENCE Paper - 2 CLASS X 2. Chemical Bonding Electrovalent, covalent and co-ordinate bonding, structures of various compounds, Electron dot structure. (a) Electrovalent bonding: • Electron dot structure of Electrovalent compounds NaCl, MgCl2, CaO. • Characteristic properties of electrovalent compounds – state of existence, melting and boiling points, conductivity (heat and electricity), dissociation in solution and in molten state to be linked with electrolysis. (b) Covalent Bonding: • Electron dot structure of non-polar covalent molecules on the basis of duplet and octet of electrons (example: hydrogen, chlorine, oxygen, nitrogen, carbon tetrachloride and methane. • Polar Covalent compounds – based on difference in electronegativity: Examples – HCl, NH3 and H2O including electron dot structures. • Characteristic properties of Covalent compounds – state of existence, melting and boiling points, conductivity (heat and electricity), ionisation in solution. Comparison of Electrovalent and Covalent compounds. (c) Coordinate Bonding: • Definition • The lone pair effect of the oxygen atom of the water molecule and the nitrogen atom of the ammonia molecule to explain the formation of H3O+ and OHions in water and NH4+ ion. The meaning of lone pair; the formation of hydronium ion and ammonium ion must be explained with help of electron dot diagrams.

There will be one paper of two hours duration of 80 marks and Internal Assessment of practical work carrying 20 marks. The paper will be divided into two sections, Section I (40 marks) and Section II (40 marks). Section I (compulsory) will contain short answer questions on the entire syllabus. Section II will contain six questions. Candidates will be required to answer any four of these six questions. Note: All chemical process/reactions should be studied with reference to the reactants, products, conditions, observation, the (balanced) equations and diagrams. 1. Periodic Properties Properties

and

variations

of

(i) Periodic properties and their variations in groups and periods. Definitions and trends of the following periodic properties in groups and periods should be studied: • atomic size • metallic character • non-metallic character • ionisation potential • electron affinity • electronegativity (ii) Periodicity on the basis of atomic number for elements. •

The study of modern periodic table up to period 4 and Group 2 [IIA] (students to be exposed to the complete modern periodic table but no questions will be asked on elements beyond period 4 – Calcium)

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Periodicity and other related properties to be explained on the basis of nuclear charge and shells (not orbitals).

3. Study of Acids, Bases and Salts

(Special reference to the alkali metals, alkaline earth metals, halogen groups and inert gases).

(i) Simple definitions in terms of the molecules, their classification and characteristic properties. 1

(ii) Action of caustic alkalis (NaOH, KOH) on aluminium their oxides and hydroxides. Self explanatory.

(ii) Ions present in mineral acids, alkalis and salts and their solutions; use of common acid - base indicators and universal indicator, pH paper to test for acidity and alkalinity. • Examples with equation for the ionisation/dissociation of ions of acids, bases and salts. • Acids form hydronium ions (only positive ions) and alkalis form hydroxyl ions (only negative ions) with water and their effect on indicators. • Definitions - Salts are formed by partial or complete replacement of the hydrogen ion of an acid by a metal or Ionic definition of salt (To be explained with suitable examples). • Introduction to pH scale to test for acidity, neutrality and alkalinity by using pH paper or Universal indicator. • Types of salts: normal salts, acid salt, basic salt, definition and examples.

5. Mole Concept and Stoichiometry Vapour Density and its relation to relative molecular mass: • Molecular mass = 2×vapour density (formal proof not required) • Deduction of simple (empirical) and molecular formula from: (a) the percentage composition of a compound. (b) the masses of combining elements. 6. Electrolysis (i) Electrolytes and non-electrolytes. Definitions and examples. (ii) Substances containing molecules only, ions only, both molecules and ions. • Substances containing molecules only ions only, both molecules and ions.

4. Analytical Chemistry (i) Action of Ammonium Hydroxide and Sodium Hydroxide on solution of salts: colour of salt and its solution; formation and colour of hydroxide precipitated from salt solutions of Ca, Fe, Cu, Zn and Pb; special action of ammonium hydroxide on solutions of copper salt and sodium hydroxide on ammonium salts.

Examples; relating their composition with their behaviour as strong and weak electrolytes as well as non-electrolytes. (iii) Definition and explanation of electrolysis, electrolyte, electrode, anode, cathode, anion, cation, oxidation and reduction (on the basis of loss and gain of electrons). (iv) An elementary study of the migration of ions, with reference to the factors influencing selective discharge of ions (reference should be made to the activity series as indicating the tendency of metals, e.g. Na, Mg, Fe, Cu, to form ions) illustrated by the electrolysis of: •

On solution of salts: • Colour of salt and its solution. •

Action on addition of Sodium Hydroxide to solution of Ca, Fe, Cu, Zn, and Pb salts drop by drop in excess. Formation and colour of hydroxide precipitated to be highlighted with the help of equations.

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Action on addition of Ammonium Hydroxide to solution of Ca, Fe, Cu, Zn, and Pb salts drop by drop in excess. Formation and colour of hydroxide precipitated to be highlighted with the help of equations.

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Special action of Ammonium Hydroxide on solutions of copper salts and sodium hydroxide on ammonium salts.

• Molten lead bromide • acidified water with platinum electrodes • Aqueous copper (II) sulphate with active and inert electrodes; electron transfer at the electrodes. The above electrolytic processes can be studied in terms of electrolyte used, electrodes used, ionization reaction, anode reaction, cathode reaction, use of selective discharge theory, wherever applicable. (v) Applications of electrolysis. • Electroplating with nickel and silver, choice of electrolyte for electroplating. • Electro refining of copper. 2

Reasons and conditions for electroplating; names of the electrolytes and the electrodes used should be given. Equations for the reactions at the electrodes should be given for electroplating, refining of copper.

mechanism by which the back suction is avoided should be learnt. •

Reaction with ammonia

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Acidic properties of its solution reaction with metals, their oxides, hydroxides and carbonates to give their chlorides; decomposition of carbonates, hydrogen carbonates, sulphides, sulphites.

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Precipitation reactions with silver nitrate solution and lead nitrate solution.

7. Metallurgy (i) Occurrence of metals in nature: Mineral and ore - Meaning only. Common ores of iron, aluminium and zinc. (ii) Extraction of Aluminium. • •

(a) Chemical method for purifying bauxite by using NaOH – Baeyer’s Process.

B.

Ammonia Ammonia: its laboratory preparation from ammonium chloride and collection; ammonium salts. Manufacture by Haber’s Process; density and solubility of ammonia (fountain experiment); aqueous solution of ammonia; its reactions with hydrogen chloride and with hot copper (II) oxide; lead monoxide (PbO) and chlorine; the burning of ammonia in oxygen; uses of ammonia.

(b) Electrolytic extraction – Hall Heroult’s process: Structure of electrolytic cell the various components as part of the electrolyte, electrodes and electrode reactions. Description of the changes occurring, purpose of the substances used and the main reactions with their equations.

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(iii) Alloys Definition, alloys of Aluminium (only constituent elements), properties and uses. 8. Study of Compounds A. Hydrogen Chloride Hydrogen chloride: preparation of hydrogen chloride from sodium chloride; refer to the density and solubility of hydrogen chloride (fountain experiment); reaction with ammonia; acidic properties of its solution.

Laboratory preparation from ammonium chloride and collection; (the preparation to be studied in terms of, setting of the apparatus and diagram, procedure, observation, collection and identification (Tests). Ammonia from ammonium salts using alkalies.

The reactions to be studied in terms of reactants, products, conditions and equations. •

Manufacture by Haber’s Process.

Preparation of hydrogen chloride from sodium chloride; the laboratory method of preparation can be learnt in terms of reactants, product, condition, equation, diagram or setting of the apparatus, procedure, observation, precaution, collection of the gas and identification (Tests). Simple experiment to show the density of the gas (Hydrogen Chloride) – heavier than air.

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Density and solubility of ammonia (fountain experiment).

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The burning of ammonia in oxygen.

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The catalytic oxidation of ammonia (with conditions and reaction)

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Solubility of hydrogen chloride (fountain experiment); setting of the apparatus, procedure, observation, inference.

Its reactions with hydrogen chloride and with hot copper (II) oxide, lead monoxide (PbO) and chlorine (both chlorine in excess and ammonia in excess).

All these reactions may be studied in terms of reactants, products, conditions, equations and observations.

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Method of preparation of hydrochloric acid by dissolving the gas in water- the special arrangement and the

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Aqueous solution of ammonia - reaction with sulphuric acid, nitric acid, hydrochloric acid and solutions of iron(III) chloride, iron(II) sulphate,

9. Organic Chemistry (i) Introduction to Organic compounds. • Unique nature of Carbon atom – tetra valency, catenation. • Formation of single, double and triple bonds, straight chain, branched chain, cyclic compounds (only benzene).

lead nitrate, zinc nitrate and copper sulphate. C. Nitric Acid Nitric Acid: one laboratory method of preparation of nitric acid from potassium nitrate or sodium nitrate. Large scale preparation. Nitric acid as an oxidizing agent. •

(ii) Structure and Isomerism.

Laboratory preparation of nitric acid from potassium nitrate or sodium nitrate; the laboratory method to be studied in terms of reactants, products, conditions, equations, setting up of apparatus, diagram, precautions, collection and identification. (Tests)

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Manufacture of Nitric acid by Ostwald’s process (Only equations with conditions where applicable).

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As an oxidising agent: its reaction with copper, carbon, sulphur.

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(iii) Homologous series – characteristics with examples. Alkane, alkene, alkyne series and their gradation in properties and the relationship with the molecular mass or molecular formula.

D. Sulphuric Acid

(iv) Simple nomenclature. Simple nomenclature of the hydrocarbons with simple functional groups – (double bond, triple bond, alcoholic, aldehydic, carboxylic group) longest chain rule and smallest number for functional groups rule – trivial and IUPAC names (compounds with only one functional group).

Large scale preparation, its behaviour as an acid when dilute, as an oxidizing agent when concentrated - oxidation of carbon and sulphur; as a dehydrating agent dehydration of sugar and copper (II) sulphate crystals; its non-volatile nature. • Manufacture by Contact Process Equations with conditions where applicable). •

(v) Hydrocarbons: alkanes, alkenes, alkynes. • Alkanes - general formula; methane (greenhouse gas). Complete combustion of methane and ethane, reaction of methane and ethane with chlorine through substitution.

Its behaviour as an acid when dilute reaction with metal, metal oxide, metal hydroxide, metal carbonate, metal bicarbonate, metal sulphite, metal sulphide.

• Concentrated sulphuric acid as an oxidizing agent - the oxidation of carbon and sulphur. •

Structure of compounds with single, double and triple bonds. Structural formulae of hydrocarbons. Structural formula must be given for: alkanes, alkenes, alkynes up to 5 carbon atoms. Isomerism – structural (chain, position)

Concentrated sulphuric acid as a dehydrating agent- (a) the dehydration of sugar (b) Copper (II) sulphate crystals.

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Alkenes – (unsaturated hydrocarbons with a double bond); ethene as an example.

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Alkynes - (unsaturated hydrocarbons with a triple bond); ethyne as an example of alkyne.

Only main properties, particularly addition products with hydrogen and halogen namely Cl2, Br2 and I2 pertaining to alkenes and alkynes.

• Non-volatile nature of sulphuric acid reaction with sodium or potassium chloride and sodium or potassium nitrate. • Identification and Tests for both dilute and concentrated sulphuric acid.

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INTERNAL ASSESSMENT OF PRACTICAL WORK

hydroxide solution, make observations and give your deduction. Warming the mixture may be needed. Choose from substances containing Ca2+, Cu2+, Fe2+, Fe3+, Pb2+, Zn2+, NH4+. 3. Supply a solution of a dilute acid and alkali. Determine which is acidic and which is basic, giving two tests for each. 4. Add concentrated hydrochloric acid to each of the given substances, warm, make observations, identify any product and make deductions: (a) copper oxide (b) manganese dioxide.

Candidates will be asked to observe the effect of reagents and/or of heat on substances supplied to them. The exercises will be simple and may include the recognition and identification of certain gases and ions listed below. The examiners will not, however, be restricted in their choice to substances containing the listed ions. Gases: Hydrogen, Oxygen, Carbon dioxide, Chlorine, Hydrogen chloride, Sulphur dioxide, Hydrogen sulphide, Ammonia, Water vapour, Nitrogen dioxide.

EVALUATION

Ions: Calcium, Copper, Iron, Lead, Zinc and Ammonium, Carbonate, Chloride, Nitrate, Sulphide, Sulphite and Sulphate.

The assignments/project work are to be evaluated by the subject teacher and by an External Examiner. (The External Examiner may be a teacher nominated by the Head of the school, who could be from the faculty, but not teaching the subject in the section/class. For example, a teacher of Chemistry of Class VIII may be deputed to be an External Examiner for Class X Chemistry projects.)

Knowledge of a formal scheme of analysis is not required. Semi-micro techniques are acceptable but candidates using such techniques may need to adapt the instructions given to suit the size of the apparatus being used. Candidates are expected to have completed the following minimum practical work:

The Internal Examiner and the External Examiner will assess the assignments independently.

1. Action of heat on the following substances: (a) Copper carbonate, zinc carbonate

Award of Marks

(b) Zinc nitrate, copper nitrate, lead nitrate

Subject Teacher (Internal Examiner) External Examiner

(c) Hydrated copper sulphate

(20 Marks) 10 marks 10 marks

The total marks obtained out of 20 are to be sent to the Council by the Head of the school.

Make observations, identify the products and make deductions where possible (equations not required).

The Head of the school will be responsible for the online entry of marks on the Council’s CAREERS portal by the due date.

2. Make a solution of the unknown substance: add sodium hydroxide solution or ammonium

NOTE: According to the recommendation of International Union of Pure and Applied Chemistry (IUPAC), the groups are numbered from 1 to 18 replacing the older notation of groups IA …. VIIA, VIII, IB …… VIIB and 0. However, for the examination both notations will be accepted. Old IA IIA IIIB IVB VB VIB VIIB VIII IB IIB IIIA IVA VA VIA VIIA 0 notation New 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 notation

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