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Methyl cinnamate is an ester used to add strawberry flavour to foods - Scottish Highers Chemistry - Question 3 - 2015
Question 3
Methyl cinnamate is an ester used to add strawberry flavour to foods. It is a naturally occurring ester found in the essential oil extracted from the leaves of straw... show full transcript
Worked Solution & Example Answer:Methyl cinnamate is an ester used to add strawberry flavour to foods - Scottish Highers Chemistry - Question 3 - 2015
Step 1
Complete the diagram to show an apparatus suitable for carrying out this extraction.
Answer
To complete the diagram, the apparatus should include a steam generator connected to a flask containing shredded strawberry gum leaves. Additionally, a condenser must be attached to allow the steam to condense and collect the essential oil. The diagram should clearly show the pathway for steam to pass through the plant material and then for the condensed steam and essential oil to be collected.
Step 2
The essential oil extracted is a mixture of compounds. Suggest a technique that could be used to separate the mixture into pure compounds.
Answer
One effective technique for separating the mixture of compounds in the essential oil is fractional distillation or chromatography. Fractional distillation allows for the separation of components based on their different boiling points, while chromatography separates compounds based on their movement through a stationary phase.
Step 3
Show, by calculation, that cinnamic acid is the limiting reactant.
Answer
First, calculate the moles of cinnamic acid and methanol:
- Moles of cinnamic acid = ( \frac{6.5 \text{ g}}{148 \text{ g/mol}} = 0.044 \text{ moles} )
- Moles of methanol = ( \frac{2.0 \text{ g}}{32 \text{ g/mol}} = 0.0625 \text{ moles} )
Since the reaction ratio is 1:1, we find that cinnamic acid is the limiting reactant because there are only 0.044 moles available, compared to 0.0625 moles of methanol.
Step 4
Step 5
(B) Calculate the cost of cinnamic acid needed to produce 100 g of methyl cinnamate.
Answer
To produce 100 g of methyl cinnamate, first find the moles needed: Theoretical yield requires 0.617 moles (because 100 g / 162 g/mol = 0.617 moles).
Since the reaction is 1:1, 0.617 moles of cinnamic acid are required:
Mass of cinnamic acid needed = 0.617 moles × 148 g/mol = 91.356 g.
To find the cost: Cinnamic acid costs £35.00 for 250 g, thus cost per g = £35.00 / 250 g = £0.14 per g.
Total cost = 91.356 g × £0.14/g = £12.78.