(a) Write the molecular formula of X.
(i) What type of reaction is represented by the equation?
(ii) Consider the following reaction equation: C(_{12}H_2) (to) X + C(_8)H(_{18})
(iii) Draw the structure of two isomers of X.
(iv) Name the isomers drawn in (a)(iii).
(v) Write a balanced equation for the reaction between X and hydrogen.
(b) Describe one test for fats.
(c) Sulphur (IV) oxide is converted to tetraoxosulphate (VI) acid according to the following equation: 2SO(_{2(g)}) + O(_{2(g)}) + 2H(_2)O(_{(l)}) (to) 2H(_2)OSO(_{4(aq)}). If 1.5 moles of oxgen reacts with sulphur (IV) oxide, calculate the mass of tetraoxosulphate (VI) acid produced. [H = 1.0; O = 16.0; S = 32.0].
(d) Consider the following neutralization reaction:
CH(_3)COOH + NaOH (to) CH(_3)COONa + H(_2)O; (bigtriangleup)H(_1)
CH(_3)COOH + NH(_4)OH (to) CH(_3)COONH(_4) + H(_2)O; (bigtriangleup)H(_2)
NaOH + HCl (to) NaCl + H(_2)O (bigtriangleup)H(_3)
(i) Arrange the enthalphy changes for the reactions in order of increasing magnitude.
(ii) Explain briefly your order in (d)(i).
(e) Consider the following substances. Cu(_{(s)}), BeCl(_2), NaH(_{(s)}), HF(_{(s)})and CCl(_{4(l)}). State the substance(s) which;
(i) can conduct electricity;
(ii) is/are soluble in water.
Explanation
(a)(i) Structure of two isomers of X
(ii) Catalytic cracking
(iii) C(_4)H(_8) (12 – 8) = 4, (26 – 18) = 8
(iv) Name of Isomers drawn in a(iii) are: (A) But – 1- ene (B) But – 2 – ene (C) 2-methyl propene
(v) Balanced equation for the reaction between X and hydrogen.
C(_4)H(_8) + H(_2) —> C(_4)H(_{10})
(b) Test for fats: A small amount of the substance placed on a filter paper then rub or warm or melt on the filter paper. Formation of a translucent spot on the filter paper shows or indicates the presence of fats presence of fat or a small amount of the substance treated with Sudan III reagent/or Add Sudan III to the sample. Observation of a red colour shows the presence of fat.
(c) Molar mass of H(_2)SO(_4): [(1 x 2) + 32 + (4 x16)]
= 2 + 32 + 64 = 98 — 98g mol(^{-2})
1 mole of O(_{2(g)}) –> 2 moles of H(_2)SO(_2)
1.5 mole of O(_{2(g)}) –> (2 x 1.5) moles of H(_2)SO(_4) 3 moles of H(_2)SO(_4)
Mass of 3 moles of H(_2)SO(_4) = 3 x 98 = 294g.
(d) (i) Enthalpy changes for reactions in their increasing magnitude.
(bigtriangleup)H(_2) < (bigtriangleup)H(_1) < (bigtriangleup)(_3) or (bigtriangleup)H(_2) (bigtriangleup)H(_1) (bigtriangleup)H(_3), or (bigtriangleup)H(_3) > (bigtriangleup)H(_1) > (bigtriangleup)H(_2) < lesser than > greater than
(ii) The explanation in the order of arrangement in (d) (i): Neutralization involves the combination of H(^+) and OH(^-) ions to give a specific amount of energy. The greater the ionization, the greater the energy given off (bigtriangleup)H(_2) involves a weak acid and a weak base/weak electrolyte. (bigtriangleup)H(_1), involves a stronge base and a weak acid. (bigtriangleup)H(_3) involves a strong acid and a strong base.
(e) (i) Cu(_{(s)}) can conduct electricity,
(ii) NaH(_{(g)}) , BeCl(_{2(s)}), HF(_{(l)}) are soluble in water.