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Chemistry
WAEC / WASSCE 1996
Acids, Bases, pH & Salts
Ammonia gas is suitable for performing the 'Fountain' experiment because the gas is
A
colourless
B
a cooling agent
C
alkaline to litmus
D
a reducing agent
E
very soluble in water
medium Difficulty
Verified Correct Answer: Option E
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #36511)
Chemistry
WAEC / WASSCE 1996
Stoichiometry, Mole Concept & Volumetric Analysis
Which of the following metals will be the most suitable for use where lightness and resistance to corrosion are of importance?
A
Lead
B
Copper
C
Iron
D
Calcium
E
Aluminium
medium Difficulty
Verified Correct Answer: Option E
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #36512)
Chemistry
WAEC / WASSCE 1996
Stoichiometry, Mole Concept & Volumetric Analysis
What amount of copper is deposited when 13.0g of zinc reacts with excess copper (ll) tetraoxosulphate (IV) solution according to the following equation? Zn (s) + CuSO4(aq) → ZnSO4(aq) + Cu (s) [Cu =63,5, Zn = 65]
A
0.1 mole
B
0.2mole
C
0.3 mole
D
0.4 mole
E
0.5 mole
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #36513)
Chemistry
WAEC / WASSCE 1996
Stoichiometry, Mole Concept & Volumetric Analysis
The products formed when sodium hydrogen trioxocarbonate (IV) is heated strongly are
A
carbon (IV) oxide and sodium hydride
B
carbon (IV) oxide and soudium trioxocarbonate (IV)
C
sodium trioxocarbonate (IV) and steam
D
carbon (IV) oxide and steam
E
sodium trioxocarbonate (IV) carbon (IV) oxide and steam
medium Difficulty
Verified Correct Answer: Option E
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #36514)
Chemistry
WAEC / WASSCE 1996
Metals, Transition Elements & Extraction
The following are properties of transition metals except
A
variable oxidation states
B
tendency to form complext ions
C
formation of coloured ions
D
ability to act as catalyst
E
low melting points
medium Difficulty
Verified Correct Answer: Option E
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #36525)
Chemistry
WAEC / WASSCE 1996
Stoichiometry, Mole Concept & Volumetric Analysis
The following salts will produce a gas on reacting with hydrochloric acid except
A
CuSO4
B
CaCO3
C
FeS
D
Na2SO3
E
K2CO3
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #36527)
Chemistry
WAEC / WASSCE 1996
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
All your burette readings (initial and final), as well as the size of your pipette, must be recorded but no account of experimental procedure is required. All calculations must be done in your answer book.
A is a solution of tetraoxosulphate (VI) acid. B is a solution containing 1.4g of potassium hydroxide per 250cm\(^3\)
(a) Put A into burette and titrate with 20.0cm\(^3\) or 25.0cm\(^3\) portions of B using methyl orange or screened methyl orange as indicator. Record the volume of your pipette. Tabulate your burette readings and calculate the average volume of A used.
(b) From your results and the information provided, calculate the:
(i) concentration of B in mol.dm\(^{-3}\)
(ii) concentration of A in mol dm\(^{-3}\)
(iii) number of hydrogen ions in 1.0dm\(^{-3}\) of A. The equation for the reaction is: H\(_2\)SO\(_4\) + 2KOH \(\to\) K\(-2\)SO\(_4\) + 2H\(_2\)O. [H= 1, O = 16; K = 39. Avogadro constant = 6.0 x 10\(^{23}\)]
(c) State whether the pH of the following would be equal to 7, greater than 7 or less than 7
(i) Solution A:
(ii) Titration mixture of A and B before the endpoint
A
CuSO4
B
CaCO3
C
FeS
D
Na2SO3
E
K2CO3
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Volume of base used (pipette) = 25.00 cm\(^3\);
Burette reading
Rough
1st
2nd
3rd
Final burette readings (cm\(^3\))
18.60
18.00
20.30
28.00
Initial urette readigs (cm\(^3\))
0.00
0.00
2.30
10.00
Volume of acid used (cm\(^3\))
18.60
18.00
18.00
18.00
Average volume of the acid = \(\frac{18.00 18.00 18.00}{3}\) = 18.00 cm\(^{3}\)
(b)(i) Mass of KOH per dm\(^3\) of B = \(\frac{1.4 \times 1000}{250}\) = 5.6 g/dm\(^{-3}\)
Molar mass of KOH = 39 + 16 + 1 = 56g
Concentration of B = \(\frac{5.6}{56}\) = 0.01 mol dm\(^{-3}\)
(b)(ii) Equation for the reactions; H\(_2\)SO\(_4\) + 2KOH \(\to\) K\(_2\)SO\(_4\) + 2H\(_2\)O
From the equation,
Concentration of A (C\(_A\)) x volume of A(V\(_A\)) mole ratio \(\frac{A}{B}\)
Concentratio B(C\(_A\)) x volume of (V\(_B\))
\(\frac{C_A \times 18.00}{0.10 \times 25}\) = \(\frac{1}{2}\)
C\(_A = \frac{0.10 \times 25}{2 \times 18.00}\) = 0.0694 mol/dm\(^3\)
(b)(iii) 1 dm\(^3\) of 1.0 mol/dm\(^3\)
H\(_2\)SO\(_4\) contains (2 x 6.0 x 10\(^{23}\))
Hydrogen atom 1 dm\(^3\) of 0.0694 mol dm\(^{-3}\)
H\(_2\)SO\(_4\) contains = (2 x 6.0 x 10\(^{23}\) x 0.6694) 8.328 x 10\(^{22}\) x 10\(^{22}\)
(c)(i) Less than
(ii) Greater than; C is NaHCO\(_3\); D is Pb(NO\(_3\))\(_2\)
Source: Official Exam / Past Question Archive
Chemistry
WAEC / WASSCE 1996
Organic Chemistry I: Hydrocarbons & Crude Oil
Solution
(a) List two gases which are monatomic
(b) Mention one gas which forms:
(i) dense white fumes with ammonia vapour
(ii) yellow precipitate with ammoniacal silver trioxonitrate (V) solution.
medium Difficulty
Verified Correct Answer: Option
Chemical Principles & Mechanism
(a) Helium or Neon or Argon (i.e. all noble gases)
(b)(i) Hydrogen chloride gas
(ii) Ethyne of propyne or but-1-nye.
Source: Myschool Past Questions Archive (Record #54314)
Chemistry
WAEC / WASSCE 1996
Kinetic Theory of Matter & Gas Laws
Solution
(a) State three postulates of the kinetic theory
(b) Name the process involved in the;
(i) spread of the smell of a perfume across a room
(ii) decrease in the yellow of a liquid after exposure in an open vessel.
medium Difficulty
Verified Correct Answer: Option
Chemical Principles & Mechanism
(a)(i) Particles of matter are in constant or continuous motion
(ii) The particles move randomly in straight lines and colliding with one another
(iii) The forces of attraction or repulsion are negligible
(b)(i) Diffusion (ii) Evaporation.
Source: Myschool Past Questions Archive (Record #54315)
Chemistry
WAEC / WASSCE 1996
Acids, Bases, pH & Salts
Solution
(a) What is the anhydride of each of the following acids?:
(i) H\(_2\)SO\(_4\)
(ii) HNO\(_3\)
(b) Classify each of the: following as normal salt/acid salt/basic salt/double salt
(i) Sodium hydrogentrioxocarbonate (IV)
(ii) Iron (III) chloride
(iii) Sodium ethanoate.
medium Difficulty
Verified Correct Answer: Option
Chemical Principles & Mechanism
(a)(i) SO\(_3\)
(ii) N\(_2\)O\(_3\) or NO\(_2\)
(b)(i) Acid salt
(ii) Normal salt
(iii) Normal salt.
Source: Myschool Past Questions Archive (Record #54318)
Chemistry
WAEC / WASSCE 1996
Non-Metals & Their Compounds
Solution
(a)(i) State two physical properties of hydrogen sulphide
(ii) Name the laboratory equipment used for intermittent production of hydrogen sulphide
(b) What property of hydrogen sulphide is illustrated in the reaction represented by the following equation?
H\(_2\)S\(_{(g)}\) + 2NaOH\(_{(aq)}\) \(\to\) Na\(_2\)S\(_{(aq)}\) + H\(_2\)O\(_{(l)}\)
medium Difficulty
Verified Correct Answer: Option
Chemical Principles & Mechanism
(a)(1) colourless gas at room temperature
(2) repulsive or smell like rotten egg
(ii) Kipp's apparatus
(b) Acidic properties
Source: Myschool Past Questions Archive (Record #54319)
Chemistry
WAEC / WASSCE 1996
Periodic Table & Periodicity
Solution
(a) The elements listed below to the same group in the Periodic Table \(_9F\) \(_{17}CI\) \(_{35}Br\) \(_{53}I\).
(i) Write the electronic structure of the first member
(ii) What is the family name of the elements.
(iii) Which of the elements has the strongest oxidizing ability?
(b) Use the information provided in the following table to answer Questions (i) to (ii) below
(b)(i) Which of the chlorides would exist as discrete molecules?
(ii) What type of bonding holds atoms of A and chlorine together in ACI?
(iii) Which of the chlorides would be a good conductor of electricity?
medium Difficulty
Verified Correct Answer: Option
Chemical Principles & Mechanism
(a)(i) 1s\(^2\)2s\(^2\)2p\(^{5}\) or 2,7
(ii) Halogen
(iii) Fluorine of F
(b)(i) BCl\(_4\)
(ii) Ionic or Electronic bonding
(iii) ACI.
Source: Myschool Past Questions Archive (Record #54320)
Chemistry
WAEC / WASSCE 1996
Water, Solutions & Solubility
Solution
(a) (i)Name the class of oxides to which copper (II) oxide belongs.
(ii) Give the reason why copper (II) oxide increases in mass on exposure to the atmosphere
(iii) Write an equation to show the action of dilute hydrochloric acid on copper (II) oxide.
(b) List two methods of removing total hardness from water.
medium Difficulty
Verified Correct Answer: Option
Chemical Principles & Mechanism
(a)(i) Basic oxide
(ii) It is hygroscopic or absorbs water from atmosphere on exposure (but does not form solutions)
(iii) CuO + 2HCI --> CuCl\(_2\) + H\(_2\)O
(b)(i) Use of washing soda
(ii) Use of ion-exchange resin/permutit process
(iii) Distillation or fractional distillation.
Source: Myschool Past Questions Archive (Record #54340)
Chemistry
WAEC / WASSCE 1996
Chemical Energetics & Thermochemistry
Solution
Use the following energy profile diagram to answer Questions (a) to (c) below.
(a) From the diagram, determine the value of the; (i) enthalpy of the reaction (ii) activation energy of the reaction.
(b) State whether the profile diagram is for an endothermic reaction or an exothermic reaction.
(c) What name is given to substances which can provide an alternative pathway for the reaction?
medium Difficulty
Verified Correct Answer: Option
Chemical Principles & Mechanism
(a)(i) Enthalpy = (50 -150) KJ mol\(^{-1}\) = - 100 KJ mol\(^{-1}\)
(ii) Activation energy = (350 - 150) KJ mol\(^{-1}\) = 200KJ
(b) It is for an exothermic reaction
(c) Catalyst or promoters or inhibitors.
Source: Myschool Past Questions Archive (Record #54341)
Chemistry
WAEC / WASSCE 1996
Organic Chemistry II: Functional Groups, Polymers & Biomolecules
Solution
(a) Give the name of the:
(i) process for obtaining ethanol from sugars;
(ii) compound produced when ethanol undergoes bacterial oxidation.
(iii) enzyme in yeast which catalyses the conversion of maltose to glucose.
(b)(i) Write the structural formula of ethanol
(ii) Name the organic product formed when propanoic acid reacts with ethanol.
medium Difficulty
Verified Correct Answer: Option
Chemical Principles & Mechanism
(a)(i) Fermentation
(ii) Ethanoic acid or ethanal
(iii) Maltase.
(b)(i)
(ii) Ethyl Propanoate
Source: Myschool Past Questions Archive (Record #54342)