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(a) (i) Give reason why carbon can neither form $\ce{C^{4+}}$ cation nor $\ce{C^{4-}}$ anion, but forms covalent compounds.
(ii) What happens when :
(I) a piece of sodium is dropped into ethanol ($\ce{CH3CH2OH}$) ?
(II) ethanol ($\ce{CH3CH2OH}$) is heated with ethanoic acid ($\ce{CH3COOH}$) in the presence of an acid ?
(iii) Define soap. Why are soaps not effective in hard water?
(ii) What happens when :
(I) a piece of sodium is dropped into ethanol ($\ce{CH3CH2OH}$) ?
(II) ethanol ($\ce{CH3CH2OH}$) is heated with ethanoic acid ($\ce{CH3COOH}$) in the presence of an acid ?
(iii) Define soap. Why are soaps not effective in hard water?
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(a) (i) To form $\ce{C^{4+}}$ ion large amount of energy is required to remove 4 electrons. For forming $\ce{C^{4-}}$ anion, it would be difficult for the nucleus with six protons to hold on to ten electrons, that is, four extra electrons. Hence energetically not feasible. Hence carbon completes its octet by sharing of electrons and forms covalent bonds. (2 Marks)
(ii) (I) Sodium ethoxide and Hydrogen gas are formed / $\ce{2Na + 2CH3CH2OH -> 2CH3CH2O-Na+ + H2}$ (1 Mark)
(II) $\ce{CH3COOC2H5}$ is formed / Ester is formed / $\ce{CH3-COOH + CH3-CH2OH ->[Acid] CH3-C-O-CH2-CH3 + H2O}$ (1 Mark)
(Either statement or equation is to be marked)
(iii) Sodium or Potassium salt of long chain carboxylic acid. ($\frac{1}{2}$ Mark)
Because soap forms scum with hard water. ($\frac{1}{2}$ Mark) (5 Marks)
(ii) (I) Sodium ethoxide and Hydrogen gas are formed / $\ce{2Na + 2CH3CH2OH -> 2CH3CH2O-Na+ + H2}$ (1 Mark)
(II) $\ce{CH3COOC2H5}$ is formed / Ester is formed / $\ce{CH3-COOH + CH3-CH2OH ->[Acid] CH3-C-O-CH2-CH3 + H2O}$ (1 Mark)
(Either statement or equation is to be marked)
(iii) Sodium or Potassium salt of long chain carboxylic acid. ($\frac{1}{2}$ Mark)
Because soap forms scum with hard water. ($\frac{1}{2}$ Mark) (5 Marks)