Candidate S Signature

NAME...... INDEX NO......

CANDIDATE’S SIGNATURE......

DATE......

233/1

CHEMISTRY

PAPER 1

THEORY

MARCH/ APRIL 2013

TIME: 2 HOURS

LAINAKU EXAMINATION

INSTRUCTIONS TO CANDIDATES

a)Mathematical tables and calculators may be used.

b)All working MUST be clearly shown where necessary.

FOR EXAMINER’S USE ONLY

QUESTIONS / MAXIMUM SCORE / CANDIDATES SCORE
1 -30 / 80

1.Study the diagram below and answer the questions that follows. The diagram shows the method of separating components of mixture Q.

(i)State the role of the part labeled X.(1mk)

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(ii)State what would happen if the water inlet and water outlet in the Liebig condenser is interchanged . (1mk)

2.a) Define Gay – Lussac’s law.(1mk)

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b)30cm3 of ethane were mixed with 100cm3 of oxygen and the mixture was sparked to complete reaction. If all the volume were measured at a pressure of one atmosphere and a temperature of 25°C, Calculate the volume of the residual gas under.

State condition.(2mks)

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3.The diagram below shows a diagram of non – luminous flame. A piece of white paper is

slipped into the region of the flame as shown in the diagram and quickly removed before it catches fire.

a)Draw and label the piece of paper to show how it is affected by the above flame.(2mks)

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b)Explain why a luminous flame of a bunsen burner produces bright yellow light.(1mk)

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4.A student added 50 cm3 of 1.0M aqueous sulphuric acid to 50cm3 of 2.0M potassium hydroxide and the temperature rose by 4°C.

a)Define the term molar heat of neutralization.(1mk)

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b)Calculate the molar heat of neutralization . ( C = 4.2 kJk-1 density of solution = 1g/cm3.

(2mks)

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5.Study the set –up below and answer the questions that follow.

a)Identify the gas produced in the flask.(1mk)

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b)Using an equation explain the observation made in the boiling tube.2mks)

6.Write the structure of the polymer.

(i)formed by the following monomer.(1mk)

CH2 = CH

(ii)Give the IUPAC name of the following organic compound.(1mk)

CH2(Cl) CH2(CH3)CH2CH2CH3

7.The set – up below was used by a student to try to prevent the rusting of an Iron rod.

(a)Did the student succeed in preventing the rusting of Iron using the set – up above? (2mks)

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b)Which method of rust prevention was the student investigating.(1mk)

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8.When potassium nitrate is heated, it produces potassium nitrite and gas C.

a)Identity gas C.(1mk)

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b)Name the type of reaction undergone by the potassium nitrate.(1mk)

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9.The chromatogram below shows the constituents of ink sample M using methylated spirit as solvent.

a)Describe how you would obtain a solid sample of the red pigment from the chromatogram above. (2mks)

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10.Calculate the number of hydrogen ions in 5cm3 of 0.5 molar phosphoric acid. ( L = 6.0 x 1023)

(2mks)

11.The following table shows the pH values of solutions A, B,C and D.

Solution / A / B / C / D
pH / 3 / 7 / 10 / 14

(i)Which solution is likely to be that of iron (III) Chloride.(1mk)

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(ii)Which solution has the highest concentration of hydroxide ion. Explain.(2mks)

12.The diagram below shows a structure (i) of water molecules

i)Name the bonds labelled(1mk)

a) ………………………………………………………………………………………….

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b…………………………………………………………………………………………..

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ii)Using dots (.) and cross(x) diagram show the bonding in the compound phosphonium ion

PH4+(H = 1, P = 15)(2mks)

13.A form one student set – up the apparatus below to investigate the property of steam on aluminium.

(a)Explain why no gas was collected in the above set –up.(1mk)

(b)Aluminium reacts with steam to form aluminium oxide and not alumunium hydroxide as expected . Explain. (1mk)

( c)Explain why the reaction between aluminium and steam stops after a short time.

(1mk)

14.The table below shows properties of some elements. Study it carefully and answer the questions that follow.

Element / Sodium / Magnesium / Phosphorus
Electrical conductivity / Good / Good / Poor
Melting point / 98 / 660 / 44 44 or 115

a)Suggest why phosphors has been a signed two melting point values.(1mk)

b)Explain why the melting point of magnesium is higher than that of sodium.(1mk)

15.1.512g of metal carbonate XCO3 reacts with 20cm3 of 1.8M hydrochloric acid completely.

Calculate the relative atomic mass of element X. (C = 12, O = 16)(3mks)

16.A wooden splint glowing on both ends was fixed as shown in the diagram. The experiment was carried out as indicated.

a)What will be observed on the glowing splint ends A and B if heating is done at the same time. (1mk)

b)Explain the observation in (a) above.(1mk)

c)One of the products in this experiment is useful to rocket scientist is useful to rocket scientists when going into space.State two ways in which the scientists use this product. (1mk)

17.30cm3 of Hydrogen gas diffuses through a porous plug in 2 minutes. How long will 90cm3

of hydrocarbon gas of molecular mass 72 taken to diffuse through the same plug under same conditions. ( H = 1 , C = 12) (3mks)

18.The diagram below represents a charcoal burner. Study it and answer at the question that follow.

a)Explain what takes place in region (III)(2mks)

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b)Write an equation for the reaction taking place in region II.(1mk)

19.When aqueous mixture containing 60g of potassium bromide and 7g of potassium sulphate in 100g of water at 80°C was cooled to 0°C some crystals were formed.

(i)Name the method used to obtain the crystals.(1mk)

(ii)Suggest one industrial application of the method named in (i) above.(1mk)

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20Give two reasons why ammonium nitrate is such a good fertilizer.(2mks)

21.The table below gives information of four elements by letters A,B, C and D. Study it and answer the questions that follow. The letters do not represent the actual symbol of the elements.

Element / Electron arrangement / Atomic radius (nm) / Ionic radius nm
A / 2.8.2 / 0.136 / 0.065
B / 2.8.7 / 0.097 / 0.181
C / 2.8.8.1 / 0.203 / 0.133
D / 2.8.8.1 / 0.174 / 0.097

a)Which two elements have similar properties ? Explain(2mks)

b)Why is the ionic radius any element B greater than its atomic radius.(1mk)

22.In an experiment soap solution was added to three samples of water. The table below shows the volume of soap solution required to form lather with 500cm3 of water before and after boiling.

Sample A / Sample B / Sample C
Volume of soap before water is boiled / 12.4 / 4.0 / 29.0
Volume of water after water is boiled / 4.0 / 4.0 / 29.0

a)Which sample is likely to be

(i)temporary hard water.(1mk)

(ii)permanent hard water.(1 mk)

b)Write the formula of a compound that could be present in sample A but not in sample C. (1mk)

23.Starting with zinc oxide, describe how you can prepare a sample of lead ( II) sulphate. (2mks)

24.Given phosphorus has atomic number of 15. Write the electron arrangement of phosphorous in PO43-. ( 2mks)

25.Study the information in the table below and answer the questions that follow. The letters are not the actual symbols of the elements.

Substance / Solubility in water / Electrical conductivity
Solid / Molten
K
L
M / Insoluble
Soluble
Insoluble / Good
Poor
Poor / Good
Good
Poor

a)Which of the substance is likely to be sodium chloride.(1mk)

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b)What type of bond exists in substance K(1mk)

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26.When hydrogen gas is passed over Lead (II) oxide in a combustion tube, Lead (II) oxide is reduced.

a)Write an equation for the above reaction(1mk)

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b)What observation was made in the combustion tube when the reaction was complete.

(1mk)

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c)Name another gas which can be used to reduce Lead (II) Oxide.(1mk)

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27.A colourless gas T is slightly soluble in water forming a neutral solution. The gas does not support burning and forms brown fumes when exposed to air.

a)Write an equation for the reaction between gas T and air.(1mk)

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b)Identify the brown gas.(1mk)

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28.In the last stage of the Solvay process a mixture of sodium hydrogen carbonate and ammonium chloride is formed.

i)State the method of separation used.(1mk)

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ii)Write an equation showing how lime is slaked.(1mk)

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iii)Name the by – products recycled in the above process.(1mk)

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29.A compound X is made of carbon, hydrogen and oxygen whose percentage composition by mass are 62.1%, 10.3% and the rest oxygen respectively. The relative molecular mass of X is 58 ( H = 1 0 = 16 C= 12)

a)Determine the empirical formula of the compound.(3mks)

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b)Determine the molecular formulae of the compound.(1mk)

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100cm3 of air is continuously passed through a combustion tube connected to two syringes as shown below. The combustion tube contains some clean granules of copper metal which are heated. The process is repeated until there is no further change in the volume of air. The volume of air remaining is 80cm3

i)State one observation made in the combustion tube 1 mark

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ii)Work out the percentage of air used after the reaction2 marks

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iii)List two gases remaining after the reaction 1 mark

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