(a)(i) State Faraday’s first law of electrolysis. (ii) Distinguish between a strong electrolyte and a weak electrolyte
(b) State one chemical property of ethyne.
(c)( i) What is meant by the tern unsaturated hydrocarbon? (ii) Complete the following reaction equation: CH\(_3\) + CH\(_3\)OH-> (iii) Name the major product formed in the cation stated in 1(c)(ii).
(d) State one way by which the rate of esterification could be increased.
(e) Consider the reaction represented by the following equation: Zn + H\(_2\)SO4 → ZnOS\(_4\) + H\(_2\) . If 3.75g of Zn dust was added to excess H\(_2\)SO\(_4\). Calculate the number of molecules of hydrogen gas produced. [ Zn = 65.0, Na = 6.02 X10\(^23\) ].
(f) State one effect of global warming.
(g) Consider the following reaction equation:
A. Pb(NO\(_3\)) +H\(_2\)S –> PbS + 2HNO\(_3\);
B. H\(_2\) + C\(_2\)H\(_4\) → C\(_2\)H\(_6\).
C. Zn(OH)\(_2\) + 2OH → [ Zn(OH)\(_4\) ]\(^2\).
(i) Which of the equations represent(s) redox process? (ii) State the change in Oxidation number of the species that are oxidized or reduced. (h)(i) State two of the main concepts of Bohr’s model of the atom. (ii) State the limitations of Bohr’s model. (i) List three factors that could influence the equilibrium position of a reversible reaction. (j) Calcium trioxocarbonate(iv) powder is added to separate equimolar solutions of hydrochloric acid and ethanoic acid. State one: (i) similarity in the observation in both reactions: (ii) difference in the observation in both reactions.
Explanation
(a) (i) Faraday's first law of electrolysis states that the amount of a substance discharged at/dissolved from an electrode is directly proportional to the quantity of electricity that passes through the electrolyte.
OR
- The mass of an element deposited at the electrode is directly proportional to the quantity of electricity passed.
(ii) Strong electrolytes dissociate/ionize completely in aqueous solutions while weak electrolytes dissociate/ionize only slightly/partially in aqueous solution.
(b)
-it burns in air/oxygen;
- it undergoes addition reaction;-it undergoes polymerization,
- it undergoes substitution/precipitation reaction.
(c)i) hydrocarbon with double/triple bond/multiple bonds between at least a pair of carbon atoms.
(ii) CH\(_3\)COOH + CH\(_3\)OH ⇌ CH\(_3\)COOCH\(_3\) + H\(_2\)
(ii) Methylethanoate (d) addition of concentrated H\(_2\)SO\(_4\) ; - removal of the ester as soon as it forms; - increase the concentration of one of the reactants.
(e) 65.0g of Zn\(^2+\) will produce 6.02 x 10\(^23\) molecules of H\(_2\), OR 65.0g Zn = I molecule of H\(_2\)
∴ 3.75g of Zn = \(frac{3.75}{ 65}\) X 6.02 x 10\(^23\)
= 3.4 X 10 molecules
(f) Sea level rising: -severe climate changes,depletion of coral reefs; -alters ecosystem balance/setting animal on the move; - severe drought; flooding or( areas); - polar ice melting
(g)(i) equation B, H\(_2\) +C\(_2\)H\(_4\) --> C\(_2\)H\(_6\)
(ii) In equation B, H changes from zero to-1; C changes from +2 to +3 as Concentration (i)
(h)(i) an electron in an atom exists/revolves a circular orbit; - energy of an electron is quantified / has a fixed value; - an electron emits energy in the form of radiation when it moves from a higher energy state to a lower energy State.
(ii) Bohr's model cannot explain the more complicated spectra lines observed in spectra Other than that of hydrogen. (i) temperature; pressure/volume; -concentration
(j) (i) produces a gas/effervescence/bubbles- given off;- HCI will produce a more vigorous reaction/CH\(_3\)COOH will produce a less vigorous reacton.