Question

Use structural formulas to write the equation for the condensation reaction between ethanol and propanoic acid.

Short answer

The condensation reaction between ethanol (CH3-CH2-OH) and propanoic acid (CH3-CH2-COOH) can be represented by the balanced chemical equation: \(CH_3-CH_2-OH + CH_3-CH_2-COOH \rightarrow CH_3-CH_2-O-CH_2-CH_3 + H_2O\). This reaction results in the formation of an ester (CH3-CH2-O-CH2-CH3) and water (H2O) as a byproduct.

Step-by-step solution

1. Write the structural formulas of the reactants

Ethanol (C2H5OH) has the structural formula: CH3-CH2-OH Propanoic acid (C3H6O2) has the structural formula: CH3-CH2-COOH

2. Identify the groups to be involved in the condensation reaction

In a condensation reaction between an acid and an alcohol, the carboxyl group (-COOH) in the acid and the hydroxyl group (-OH) in the alcohol will react to form an ester and water.

3. Form the ester group

To form the ester, the hydrogen in the hydroxyl group of ethanol and the hydroxyl group in propanoic acid will be removed. The remaining O from the ethanol will bond with C from the propanoic acid to form the ester group. The ester formed will have the structural formula: CH3-CH2-O-CH2-CH3, where O is the ester group.

4. Write the balanced chemical equation

Now we can write the balanced chemical equation for the condensation reaction: CH3-CH2-OH + CH3-CH2-COOH -> CH3-CH2-O-CH2-CH3 + H2O In summary, the condensation reaction between ethanol and propanoic acid results in the formation of an ester molecule (CH3-CH2-O-CH2-CH3) along with water as a byproduct (H2O).

Key concepts

Structural Formulas

Structural formulas are a detailed depiction of molecules showing how atoms are bonded within the molecule. This is more informative than a simple molecular formula which only provides the type and number of atoms present. Let's see how this is represented for the molecules involved in our reaction.

• Ethanol: The structure of ethanol is represented as CH\(_3\)-CH\(_2\)-OH. This translates to a chain of two carbon atoms (C), with hydroxyl (OH) attached, and hydrogen atoms (H) completing the outer valences of carbon atoms.
• Propanoic Acid: It has the structural formula CH\(_3\)-CH\(_2\)-COOH. This includes a carboxyl group (COOH) at the end of a three-carbon chain.

These structural formulas highlight how each atom is connected and help visualizing how reactions can occur.

Ethanol

Ethanol, a simple alcohol, is often found in alcoholic beverages. It’s a two-carbon alcohol with the chemical formula C\(_2\)H\(_5\)OH. The structure CH\(_3\)-CH\(_2\)-OH is important as it shows where the hydroxyl group (-OH) is attached, letting us understand its behavior in chemical reactions, like condensation, that often involve alcohols.

• Ethanol is an important reactant in forming esters through condensation reactions.
• The hydroxyl group present in ethanol is typically the reactive site for ester formation when reacting with acids like propanoic acid.

Ethanol’s reactivity lies in the presence of the hydroxyl group, making it key to various chemical transformations.

Propanoic Acid

Propanoic acid, also known as propionic acid, is a carboxylic acid characterized by the formula C\(_3\)H\(_6\)O\(_2\) or structurally as CH\(_3\)-CH\(_2\)-COOH. Found naturally in some dairy products, it has commercial uses as a preservative and antimicrobial agent.

• Its reactive carboxyl group (COOH) is crucial in condensation reactions where it interacts with alcohols to form esters.
• In our example, this group plays a key role in bonding with the ethanol molecule, resulting in ester formation and release of water.

Understanding its structure and reactivity can provide insights into its role in biological and industrial chemistry.

Ester Formation

Ester formation is a key outcome of a condensation reaction between an alcohol and a carboxylic acid. During this process, a molecule of water is removed, hence the name 'condensation.' Let's look at what happens in our specific example with ethanol and propanoic acid.

• The hydroxyl group (-OH) of the ethanol combines with the hydrogen from the carboxyl group (-COOH) in propanoic acid.
• This departure of a water molecule (H\(_2\)O) leads to the creation of an ester bond, commonly represented by CO-O-C linkage.

In our case, the resulting ester has the structural formula CH\(_3\)-CH\(_2\)-O-CO-CH\(_2\)-CH\(_3\), accompanied by water as the byproduct. Esters are known for their pleasant aromas and are often used in perfumes and flavorings.