What is the maximum yield of dibenzalacetone that could be obtained (in grams) if 8.1 g of acetone was used as the starting material (assuming that acetone is the limiting reagent)? Molecular weight of acetone is 58.08 and density is 0.79 at room temperature; MW of dibenzalacetone is 234.30. Write your answer correct to two decimal places.
The Correct Answer and Explanation is :
To determine the maximum yield of dibenzalacetone, we need to use stoichiometry and the fact that acetone is the limiting reagent. Let’s break down the process step-by-step:
Step 1: Write the reaction for the synthesis of dibenzalacetone.
The reaction between acetone and benzaldehyde to form dibenzalacetone is:
[
\text{2 C}_6\text{H}_5\text{CHO (benzaldehyde)} + \text{CH}_3\text{COCH}_3 \text{ (acetone)} \rightarrow \text{C}_6\text{H}_5\text{CH=CHC(C}_6\text{H}_5)_2 \text{ (dibenzalacetone)} + \text{H}_2\text{O}
]
The mole ratio is 2:1 for benzaldehyde to acetone. Therefore, two moles of benzaldehyde react with one mole of acetone to form one mole of dibenzalacetone.
Step 2: Calculate the moles of acetone used.
Given that the mass of acetone is 8.1 g and the molecular weight of acetone is 58.08 g/mol, we can calculate the moles of acetone:
[
\text{Moles of acetone} = \frac{\text{Mass of acetone}}{\text{Molecular weight of acetone}} = \frac{8.1 \, \text{g}}{58.08 \, \text{g/mol}} = 0.1394 \, \text{mol}
]
Step 3: Determine the moles of dibenzalacetone produced.
Since the mole ratio of acetone to dibenzalacetone is 1:1 (from the balanced equation), the moles of dibenzalacetone produced will also be 0.1394 mol.
Step 4: Calculate the mass of dibenzalacetone.
Now, we can calculate the mass of dibenzalacetone using its molecular weight (234.30 g/mol):
[
\text{Mass of dibenzalacetone} = \text{Moles of dibenzalacetone} \times \text{Molecular weight of dibenzalacetone} = 0.1394 \, \text{mol} \times 234.30 \, \text{g/mol} = 32.68 \, \text{g}
]
Final Answer:
The maximum yield of dibenzalacetone that could be obtained is 32.68 g.
Explanation:
This is a limiting reagent problem where we use stoichiometry to determine the maximum theoretical amount of product. Since acetone is the limiting reagent, we calculate the moles of acetone and use the mole ratio to determine the moles of dibenzalacetone formed. Finally, by multiplying the moles of dibenzalacetone by its molecular weight, we find the theoretical yield in grams.