Burette readings (initial and final) must be given to two decimal places. Volume of pipette used must also be recorded but no account of experimental procedure is required. All calculations must be done in your answer book.
A is a solution of hydrochloric acid. B is a solution containing 2.45g of anhydrous sodium trioxocarbonate (IV) in 250g of solution.
(a) Put A into the burette and titrate it against 20.0 cm\(^3\) or 25.0 cm\(^3\) portion of B using methyl orange as an indicator. Repeat the exercise to obtain consistent titres. Tabulate your burette reading and calculate the average volume of A used. The equation for the reaction involved in the titration is Na\(_2\)CO\(_{3(aq)}\) + 2HCI\(_{(aq)}\) + H\(_2\)O\(_{(l)}\)
(b) From your results and the information provided, calculate the:
(i) concentration of B in moldm\(^{-3}\)
(ii) concentration of A in moldm\(^{-3}\)
(iii) concentration of A in gdm\(^{-3}\)
(iv) volume of the gas evolved in the reaction at s.t.p.
[H = 1.00; C: 12.0; O = 16.0; Na = 23.0; Na = 23.0; Cl = 35.5; Molar Volume = 22.4 dm\(^3\)mol\(^{-3}\)]
Credit will be given for strict adherence to the instructions, for observations, precisely recorded, and for accurate inferences. All tests, observations, and inferences must be clearly entered in your answer book, in ink, at the time they are made.
C contains two cations and two anions. Perform the following exercises on C. Record your observations and identify any gas (es) evolved. State the conclusion you draw from the result of each test.
(a) Dissolve all of C in about 10 cm\(^3\) of distilled water. Stir the resulting solution thoroughly.
(i) To about 2 cm\(^3\) of the solution, add few drops of AgNO\(_3\) solution, followed by HNO\(_{3(aq)}\). To the mixture, add excess NH\(_{3(aq)}\)
(ii) To another 2 cm\(^3\) portion of the solution, add dil. HCl followed by BaCl\(_2\) solution.
(iii) To another 2 cm\(^3\) portion of the solution, add NaOH\(_{3(aq)}\) dropwise and then in excess. Warm the mixture.
(iv) To another 2 cm\(^3\) portion of the solution, add NH\(_{3(aq)}\) dropwise and then in excess.
Consider the following experimental set-up.
(i) Identify by name: P; Q; R; S and T.
(ii) State the method of collection of gas, S.
(iii) What is the function of R in the experimental set-up?
(iv) Write the balanced equation of the reaction for the preparation of gas S.
(a)(i) Define the term functional group.
(ii) Name the functional groups present in the following compound:
(b) Consider the following structure of an organic compound, Q.
(1) Name compound Q.
(ii) Write the balanced equation for the complete combustion of compound Q.
(iii) What type of reaction will compound Q undergo with chlorine?
(vi) Draw the structure of-the alkene that is an isomer of compound Q.
(c) A chemistry student was provided with four samples of organic compounds, A, B, C, and D. Samples A and B each decolourized bromine in tetrachloromethane but only sample B reacted with a solution of ammoniacal silver trioxonitrate (V) to give a white precipitate. Sample D reacted with sodium trioxocarbonate (IV) to liberate carbon (IV) oxide. When heat was applied to the mixture of samples C and D in a test tube and drops of concentrated tetraoxosulphate (VI) acid added, a product with a fruity odour was formed.
(i) Name the family of organic compounds to which samples A, B, C, and D belong.
(ii) State why samples A and B reacted with bromine in tetrachloromethane.
(iii) State the reason why sample B gave a white precipitate with the solution of ammoniacal silver trioxocarbonate (V).
(iv) Give the name o f the reactions between’ samples C and D.
(v) State the two roles of the concentrated tetraoxosulphate (VI) acid in the reaction in (a)(iv).
(d) (i) Describe briefly the production of biogas using a biogas generator.
(ii) State two uses of biogas.
(a)(i) Explain briefly each of the following terms: I. anode; II. cathode.
(ii) Sodium and aluminium are extracted by the electrolysis of molten sodium chloride and alumina respectively. Write balanced equations for the reactions at the anode and cathode during the extraction of: I. sodium; II. aluminium.
(iii) Explain briefly why extraction of aluminium is considered environmentally friendly while that of sodium is not.
(b) Consider the reaction represented by the following equation:
K\(_2\)Cr\(_2\)O\(_7\) + HC1–> KCI + CrCl\(_3\) + H\(_2\)O + Cl\(_2\)
(i) Explain briefly why this reaction is redox.
(ii) Write balanced half equations for the reaction.
(iii) Write the over-all balanced reaction equation.
(c) During the electrolysis of molten Al\(_2\)O\(_3\), a current of 6A was passed through the electrolyte for 1 hr. 30 mins. Calculate the mass of aluminium deposited at the cathode.
(a)(i) Outline the steps involved in the purification of water for town supply.
(ii) Give two cations that can cause hardness in water.
(iii) State two disadvantages of hardness of water.
(iv) List two sources of water pollution.
(b)(i) Explain briefly why water is a good solvent for sodium chloride but not for oil.
(ii) State the function of H\(_2\)SO\(_4\) in each of the following reaction equations:
(i) C\(_2\)H\(_5\)OH\(_{(l)}\) \(\to\) C\(_2\)H\(_{4(g)}\)
(ii) MgO\(_{(s)}\) + H\(_2\)SO\(_4\)\(_{(aq)}\) —> MgSO\(_{4(aq)}\) + H\(_2\)O\(_{(l)}\)
(iii) C\(_{(s)}\) + conc. H\(_2\)SO\(_4\) –> CO\(_{(g)}\) + SO\(_{2(g)}\) + H\(_2\)O\(_{(l)}\)
(c) (i) Give the two products formed when chlorine water is exposed to sunlight.
(ii) I. Which of the compounds is suitable for the preparation of standard alkaline solution?
II. Give a reason for your answer in (c)(ii)I
(a) Define each of the following terms:
(i) ion; (ii) isotopes.
(b)(i) Consider the:element \(_{12}\)Mg and \(_{3}\)Al
I. Write the electron configuration of each element. II. Explain briefly why the first ionization energy of \(_{12}\)Mg is greater than that of \(_{13}\)Al.
(ii) Write the formulae of three different oxides of period 3 elements that react with water.
(c)(i) What are allotropes?
(ii) Name the two crystalline allotropes of carbon.
(iii) Give one industrial use of each allotrope named in (c)(ii).
(d) On warming crystals of sodium chloride with concentrated tetraoxosulphate (VI) acid, a gas was evolved.
(i) List two physical properties of the gas produced.
(ii) Write a balanced equation for the reaction.
(e) A certain chip W used in a circuit of a microcomputer has a mass of 5.68mg. Calculate the amount of W in the microcomputer. [ W = 28 gmol\(^{-1}\) ].
(a)(i) Define ionic bond.
(ii) What type of bond (s) exist (s) in: I. magnesium oxide; II. ammonium ion?
(b) Determine the oxidation number of sulphur in Na\(_2\)S\(_2\)O\(_2\).
(c) State Faraday’s first law.
(d) Give one example each of: (i) acid salt; (ii) base salt.
(e) Name the type of energy change that occurs in each of the following processes
(i) I\(_{2(s)}\) \(\to\) I\(_{2(g)}\)
(ii) Cl\(_{(g)}\) + e\(^{-}\) \(\to\) Cl\(^{-_(g)}\)
(f) State the effect of each of the following aqueous solutions on litmus paper: (i) Na\(_2\)SO\(_{4(aq)}\) (ii) AlCl\(_{3(aq)}\)
(g) Define the term efflorescence.
(h) Give two uses of activated charcoal.
(i) State one use of each of the following processes in the chemical industry: (i) hydrogenation of vegetable oil; (ii) cracking; (iii) esterification.
(j) Calculate the amount of silver deposited in moles when 10920 coulombs of electricity is passed through a solution of a silver salt. [ Faraday constant– 96500 C mol\(^{-1}\)]
The oxide from electric power station is
- A. carbon (IV) oxide
- B. copper (ll) oxide
- C. nitrogen (IV) oxide
- D. sulphur (IV) oxide
The most common process in the extraction of metals from their ore is
- A. catalysis
- B. electrolysis
- C. oxidation
- D. reduction
Which of the following gases is used to retard the vaporization of the filament in a light bulb?
- A. Argon
- B. Helium
- C. Hydrogen
- D. Oxygen
The purity of a solid sample can best be determined by its?
- A. boiling point
- B. melting point
- C. conductivity
- D. solubility
The production of biogas from the fermentation of waste materials is an example of
- A. combustion
- B. incineration
- C. refining
- D. recycling
Which of the following organic compounds could be represented by the empirical formula CH2O?
- A. Ethanal
- B. Ethane
- C. Ethanol
- D. Ethanoic acid
Consider the reaction represented by the following equation: C2H4(g)
+ 302(g) → 2CO2(g) + 2H2O(g)How many moles of ethene would be burnt to produce 0.1 mole of water?
- A. 0.05 mole
- B. 0.10 mole
- C. 0.20 mole
- D. 2.00 moles
The liquid hydrocarbon likely to be found in the fraction of crude oil used for domestic cooking is?
- A. C3H8
- B. C 5H 12
- C. C13H28
- D. C20H42
A colourless hydrocarbon with a sweet smell undergoes substitution reaction. The hydrocarbon is likely to be
- A. alkanol
- B. benzene
- C. ester
- D. methane
The enzyme that catalyses the conversion of glucose te ethanol and carbon (IV) oxide is
- A. diastase
- B. maltase
- C. ptyalin
- D. zymase
The IUPAC name of the following organic compound is HOOC – COOH
- A. ethan - 1, 2 -dioc acid
- B. ethanoic acid
- C. oxalic acid
- D. propan - 1,2-dioic acid
Which type of reaction is illustrated by the following equation? C12H26 → 5C 2H4 + C 2H6
- A. Addition
- B. Cracking
- C. Hydrogenation
- D. Polymerization
Which of the following compounds determines the octane rating of petrol?
- A. 1,2,3 - trimethyl pentane
- B. 2,3,5 - trimethyl octane
- C. 2,3,5 - trimethyl pentane
- D. 2,2,4 - trimethyl pentane