Carboxylic Acids

• What is the solubility of smaller carboxylic acids in water?

  They dissolve in all proportions
• Why do smaller carboxylic acids dissolve in water?

  They can hydrogen bond to water molecules
• How does the solubility of carboxylic acids change after C4?

  It rapidly reduces
• How strong are carboxylic acids in water?

  They are weak acids
• What can carboxylic acids displace from carbonates?

  Carbon dioxide
• What stabilizes carboxylic acid salts?

  Delocalisation
• What effect does delocalisation have on the C-O bond lengths in carboxylic acids?

  They become equal in length
• How does delocalisation affect the stability of carboxylic acid ions?

  It makes them more stable
• How does increasing chain length affect the strength of carboxylic acids?

  It makes the acid less strong
• What effect do alkyl groups have on carboxylic acids?

  They are electron releasing
• What effect do electronegative chlorine atoms have on carboxylic acids?

  They withdraw electron density
• Which is more acidic: propanoic acid or ethanoic acid?

  Ethanoic acid
• What is the naming convention for carboxylic acids?

  They end with -oic acid
• When is a number not necessary in naming carboxylic acids?

  When the acid group is at the end
• What is a -dioic acid?

  Carboxylic acid with groups on both ends
• What do carboxylic acids react with to form esters?

  Alcohols in presence of acid catalyst
• What are the two parts of an ester's name?

  Alcohol part and carboxylic acid part
• What is the general reaction for ester formation?

  Carboxylic acid + alcohol → ester + water
• What is the yield of ester formation reactions?

  About 50%
• What is required for the esterification reaction?

  A strong acid catalyst
• What happens to esters when they are hydrolysed with acid?

  They form a carboxylic acid and alcohol
• What is the effect of sodium hydroxide on esters during hydrolysis?

  It forms a carboxylic acid salt
• What is the difference in reversibility between acid and sodium hydroxide hydrolysis of esters?

  Acid hydrolysis is reversible, sodium hydroxide is not
• What is the role of excess sodium hydroxide in ester hydrolysis?

  It ensures complete hydrolysis of the ester
• What is produced when ethyl benzoate is hydrolysed?

  Sodium benzoate and methanol
• What happens when hydrochloric acid is added after hydrolysis of ethyl benzoate?

  Benzoic acid precipitates
• Why is sodium benzoate soluble in water?

  It is ionic
• Why is benzoic acid insoluble in water?

  It has a non-polar benzene ring
• What are fats and oils composed of?

  Esters of glycerol and fatty acids
• What do long chain carboxylic acids produce when hydrolysed?

  Soap, glycerol, and fatty acids
• How do long chain carboxylic acids act as soaps?

  They have hydrophilic and hydrophobic parts
• What is glycerol's solubility in water?

  It is readily soluble
• What is biodiesel made from?

  Methyl esters of long chain carboxylic acids
• Why is biodiesel considered carbon-neutral?

  Carbon dioxide is absorbed during growth
• What factors are not considered in the carbon-neutral argument for biodiesel?

  Energy for irrigation and processing
• What is the property of the long non-polar hydrocarbon chain in relation to water?

  It is hydrophobic and mixes with grease.
• How does the hydrophobic chain affect the mixing of grease and water?

  It allows grease and water to mix and wash away.
• What is glycerol also known as?

  Propane-1,2,3-triol
• Why is glycerol soluble in water?

  It forms hydrogen bonds very easily.
• In what products is glycerol commonly used?

  Cosmetics, food, and glues.