chem 1 tutorial 2 jan 2010 batch mac 2010 version

FOUNDATION IN SCIENCEChem1Tutorial 2 Batch: Jan 2010 NAME:…………….……………………Question 1( Done under Test conditions and the marks will be recorded)

a) Define the following terms clearly in terms of attraction:(i) Ionic bond

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…………………………………………………………………………….1m(ii) Covalent bond

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…………………………………………………………………………….1mb) Draw a Lewis diagram for the following:

(i) Aluminium atom, Al (ii) Nitrogen atom

(iii) Oxygen atom

3c) Draw a Dot-cross diagram for each molecule

(i) Water, H2O (ii) Ammonia, NH3

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(iii) Methane, CH4

d) Give the shape and bond angle for each molecule:(i) Water, H2O (ii) Ammonia, NH3

(iv) Methane, CH4

6e) State with reasons, whether ammonia is a polar or non-polar molecule.

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f) Explain why ammonia is soluble in water.

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Question 2Aluminium trifluoride is a solid at room temperature and the melting point of aluminium fluoride is 1291 °C. Solid AlF3 can’t conduct electricity but molten AlF3 can.

Phosphorus trifluoride is a gas at room temperature and the melting point of aluminium trifluoride is -151 °C. Solid PF3 can’t conduct electricity in solid and in molten state.

a) Draw a dot-cross diagram for each compound(i) Aluminium trifluoride (iii) Phosphorus trifluoride

b) Explain why molten aluminium fluoride can conduct electricity, but solid aluminium fluoride can’t conduct electricity can conduct electricity.

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c) State the shape and bond angle in Phosphorus trifluoride. Give reasons for your answer.

Shape:…………………….. Bond angle:…………………

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d) The molecules NF3, PF3, AsF3 and SbF3 all have the same shapes.(i) State with reasons, whether the molecule PF3 are polar or

non-polar molecules

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Question 3a) Define the following terms clearly based on electrons

(i) covalent bond

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……………………………………………………………..…………….1(ii) Ionic bond

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……………………………………………………………..…………….1b) Classify the following as ionic compound or ionic compound

(i) Calcium oxide :……………………………………………1

(ii) Sulfur dioxide :……………………………………………1

(iii) Nitrogen dioxide :……………………………………………1

(iv) Sodium chloride :……………………………………………1

(v) Nitrogen trichloride :……………………………………………1c) Describe the term ionic bond with reference to electrostatic attraction

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d) Draw a dot diagram for each atom(i) carbon (ii) Sulphur

e) Draw a dot-cross diagram for each compound(i) Carbon Dioxide (ii) Sulphur dioxide

f) State with reasons, the shape and bond angle in each compound(i) Carbon dioxide

Shape:…………………….. Bond angle:…………………

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…………………………………………………………………….3(ii) Sulphur dioxide

Shape:…………………….. Bond angle:…………………

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g) State with calculations and reasons, whether each molecule is polar or non polar.

(i) Carbon dioxide

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……………………………………………………………………..4(ii) Sulphur dioxide

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Question 4a) Draw dot diagram to show valence electron for each

(i) Carbon atom (ii) Chlorine atom

(iii) Magnesium atom (iv) Oxygen atom

b) Draw dot-cross diagram for each(i) Magnesium chloride (ii) Magnesium oxide

(iii) Carbon tetrachloride (iv) Carbon dioxide

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c) State with reasons, whether each molecule is polar or non-polar (i) Carbon dioxide

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………………………………………………………………………………..4(ii) Carbon tetrachloride

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(iii) Chloroform, CHCl3

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d) State the shape of the molecule CHCl3 with reasons

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Question 1. Write your answer is the spaces provided. Time: 15 minutes only.a) Define the following terms, based on electrostatic attraction theory.

(i) Ionic bond

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……………………………………………………………………………….1b) Define the term ‘electronegativity’.

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……………………………………………………………………………….1c) Briefly explain how the following bond is formed:

(i) Covalent bond

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……………………………………………………………………………….1(ii) Ionic bond

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……………………………………………………………………………….1The electronegativity and Group number of selected elements are given below:

Element Electronegativity value based on Pauling’s scale

Group in the Periodic table

Fluorine 4.0 17Nitrogen 3.0 15Sodium 0.9 1

You are advised to use them to answer the following parts of the questiond) Sodium atom and fluorine atom combine chemically to form a type of

compound X.(i) Name the type of bond formed in the compound X. Give reason for

your choice.

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……………………………………………………………………………….2(ii) Draw dot-cross diagram of the compound X, showing only the valence

electrons.

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(iii) Give the possible chemical formula of the compound X.

…………………………………………………………………………………1e) Nitrogen atom and fluorine atom reacts to form a compound Y.

(i) Name the type of bond formed in the compound Y. Give reason for your choice.

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………………………………………………………………………………..2(ii) Draw dot cross diagram for the compound Y, showing only the

valence electrons.

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(iii) Give the possible chemical formula of the compound Y.

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End of question.

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