CHEMISTRY 3.5 ANSWERSWORKSHEET EIGHT ORGANIC CHEMISTRY Carboxylic acids and their derivatives #11. (a) Octanoic acid (b) Propanoic acid2. (a) HCOOH (b) CH3CH2CH2COOH3. Carboxylic acids have the ability to form hydrogen bonds to themselves and also to water molecules. This means that they have high boiling points and are soluble in water. Their boiling points are higher than alcohols because they have two oxygen atoms in each molecule and are therefore able to make two hydrogen bonds between each pair of molecules (dimerize). Alcohols can make only one hydrogen bond per molecule.4. (a) CH3COOH(aq) + H2O(l) CH3COO-(aq) + H3O+(aq) (b) Weak acid (c) The magnesium ribbon would react slowly with the acid forming magnesium ethanoate and bubbles of hydrogen gas. 2CH3COOH(aq) + Mg(s) (CH3COO)2Mg (aq) + H2(g) (d) CH3COOH(aq) + NH4OH(aq) CH3COONH4 (aq) + H2O(l)5. (a) Condensation/ esterification (b) The sulfuric acid acts as a catalyst and a dehydrating agent. As a catalyst it speeds up the reaction. As a dehydrating agent it removes water from the right hand side of the equilibrium favouring the production of the ester. (c) CH3COOH + CH3CH2CH2OH CH3COOCH2CH2CH3 + H2O O O6. (a) CH3 - C (b) CH3 -CH2-CH2-C O-Cl O-Cl7. In moist air the acyl halides react readily with water to hydrolyse into the acid and HCl. The HCl gas forms visible fumes.