Task 1.2c (second sheet)
Question 3
What mass of glucose can be fermented to give 5.00g of ethanol?
C6H12O6 (aq) ---> 2C2H5OH (aq) + 2CO2 (g)
I thought I knew how to do this sort of question, but I got a different answer from the one on the sheet, and can't work out where I went wrong.
This is what I did:
Relative molecular mass of ethanol = 24 + 5 + 16 + 1 = 46
Moles of ethanol = mass/relative molecular mass = 5/46 = 0.109 mol
Moles of glucose = 1/2 * moles of ethanol = 1/2 * 0.109 = 0.0543 mol
Relative molecular mass of glucose = (6 * 12) + 12 + (6 *16) = 180
Mass of glucose = moles * relative formula mass = 180 * 0.0543 = 9.78g
The final answer on the sheet is 8.91g.
Thanks.
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1 comment:
I haven't seen the question that you're referring to, Vicky, but your working looks right to me.
- Relative masses of ethanol and glucose are both correct.
- The way that you have calculated the number of moles of ethanol, and then glucose, looks correct.
- You've then used moles x relative mass to calculate the mass of glucose so that looks right too!
I would have to see the question myself to be able to check what's gone wrong.
Sorry not to be of more help!!
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