Acetone + 2 benzaldehyde \rightarrow dibenzalacetone Molecular Weight: 234.2980
The Correct Answer and Explanation is:
Balanced Chemical Equation:
acetone+2 benzaldehyde→dibenzalacetone+water\text{acetone} + 2 \ \text{benzaldehyde} \rightarrow \text{dibenzalacetone} + \text{water}acetone+2 benzaldehyde→dibenzalacetone+water
Given:
- Volume of benzaldehyde = 8.00 mL
- Density of benzaldehyde = 1.044 g/mL (from standard reference)
- Molar mass of benzaldehyde = 106.23 g/mol
- Molar mass of dibenzalacetone = 234.30 g/mol
Step 1: Convert Volume of Benzaldehyde to Mass
mass=volume×density=8.00 mL×1.044 g/mL=8.352 g\text{mass} = \text{volume} \times \text{density} = 8.00 \ \text{mL} \times 1.044 \ \text{g/mL} = 8.352 \ \text{g}mass=volume×density=8.00 mL×1.044 g/mL=8.352 g
Step 2: Convert Mass of Benzaldehyde to Moles
moles of benzaldehyde=8.352 g106.23 g/mol≈0.0786 mol\text{moles of benzaldehyde} = \frac{8.352 \ \text{g}}{106.23 \ \text{g/mol}} \approx 0.0786 \ \text{mol}moles of benzaldehyde=106.23 g/mol8.352 g≈0.0786 mol
Step 3: Use Stoichiometry to Find Moles of Dibenzalacetone
From the balanced equation:
- 2 mol benzaldehyde → 1 mol dibenzalacetone
moles of dibenzalacetone=0.07862=0.0393 mol\text{moles of dibenzalacetone} = \frac{0.0786}{2} = 0.0393 \ \text{mol}moles of dibenzalacetone=20.0786=0.0393 mol
Step 4: Convert Moles of Dibenzalacetone to Grams
mass=moles×molar mass=0.0393 mol×234.30 g/mol≈9.2 g\text{mass} = \text{moles} \times \text{molar mass} = 0.0393 \ \text{mol} \times 234.30 \ \text{g/mol} \approx 9.2 \ \text{g}mass=moles×molar mass=0.0393 mol×234.30 g/mol≈9.2 g
✅ Final Answer (Theoretical Yield):
9.2 g of dibenzalacetone\boxed{9.2 \ \text{g of dibenzalacetone}}9.2 g of dibenzalacetone
📘 Explanation (300 words):
In organic synthesis, the theoretical yield is the maximum amount of product that can be formed from a given quantity of reactants under ideal conditions. In the case of dibenzalacetone synthesis, the reaction involves the condensation of one molecule of acetone with two molecules of benzaldehyde through an aldol condensation.
To determine the theoretical yield, the process begins by calculating the number of moles of the limiting reagent—benzaldehyde in this case. Using its density, the mass is calculated by multiplying the given volume by the density. This mass is then divided by the molar mass to determine the number of moles.
According to the balanced chemical equation, two moles of benzaldehyde react with one mole of acetone to form one mole of dibenzalacetone. Hence, the number of moles of dibenzalacetone formed is half the number of moles of benzaldehyde used. This is an example of a stoichiometric relationship derived from the coefficients in the balanced reaction.
Once the moles of dibenzalacetone are known, the theoretical mass is calculated by multiplying by the molar mass of dibenzalacetone. This value represents the maximum mass of product expected if the reaction proceeds to completion with no losses.
This method of yield determination is fundamental in laboratory synthesis and industrial chemistry. It helps chemists assess efficiency and plan scale-up strategies. The actual yield obtained is usually lower due to side reactions, incomplete conversion, or product loss during purification.
