Problem 48 - Chemistry: The Central Science

Question

Write a balanced chemical equation using condensed structural formulas for (a) the formation of butyl propionate from the appropriate acid and alcohol, (b) the saponification (base hydrolysis) of methyl benzoate.

Step-by-Step Solution

Answer

(a) CH3CH2C(O)OH + CH3(CH2)3OH → CH3(CH2)3OC(O)CH2CH3 + H2O (b) C6H5COOCH3 + NaOH → C6H5COONa + CH3OH

Step 1: (a) Formation of butyl propionate from the appropriate acid and alcohol

To form butyl propionate, we need to combine an appropriate carboxylic acid and an appropriate alcohol. Butyl propionate has the condensed structural formula CH3(CH2)3OC(O)CH2CH3. The alcohol involved is butanol, which has the condensed structural formula CH3(CH2)3OH, and the carboxylic acid involved is propanoic acid with the condensed structural formula CH3CH2C(O)OH. The reaction taking place is an esterification reaction, where an acid reacts with an alcohol to produce an ester and water as a byproduct. The balanced chemical equation is: CH3CH2C(O)OH + CH3(CH2)3OH → CH3(CH2)3OC(O)CH2CH3 + H2O

Step 2: (b) Saponification (base hydrolysis) of methyl benzoate

Saponification is the process in which an ester reacts with a base to form a carboxylate salt and an alcohol. Methyl benzoate is an ester with the condensed structural formula C6H5COOCH3. The base is typically a strong base, such as a hydroxide ion (OH-), provided by a soluble salt. Sodium hydroxide (NaOH) is commonly used for this purpose, releasing hydroxide ions when it dissolves in water. Methyl benzoate reacts with the hydroxide ions to form sodium benzoate (C6H5COONa) and methanol (CH3OH). The balanced chemical equation is: C6H5COOCH3 + OH- → C6H5COO- + CH3OH Since sodium hydroxide is the source of the hydroxide ions, the balanced equation, including the counterion, would be: C6H5COOCH3 + NaOH → C6H5COONa + CH3OH