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Percentage Yield

I'm only three weeks into A level chemistry and I need some help with a percentage yield question. The molar ratio of hexonone to 2,4-dinitrophenylhyrazone are not given in the question. How do I work out the percentage yield.

0.8500g of hexanone, C6H12O is converted into it's 2,4-dinitrophenylhyrazone during it's analysis. After isolation and purification, 2.1180g of product C12H18N4O4 are obtained. Calculate the percentage yield.
Original post by alfiedoran
I'm only three weeks into A level chemistry and I need some help with a percentage yield question. The molar ratio of hexonone to 2,4-dinitrophenylhyrazone are not given in the question. How do I work out the percentage yield.

0.8500g of hexanone, C6H12O is converted into it's 2,4-dinitrophenylhyrazone during it's analysis. After isolation and purification, 2.1180g of product C12H18N4O4 are obtained. Calculate the percentage yield.


First and foremost, can you calculate the moles of reactant and moles of product produced?
Original post by alfiedoran
I'm only three weeks into A level chemistry and I need some help with a percentage yield question. The molar ratio of hexonone to 2,4-dinitrophenylhyrazone are not given in the question. How do I work out the percentage yield.

0.8500g of hexanone, C6H12O is converted into it's 2,4-dinitrophenylhyrazone during it's analysis. After isolation and purification, 2.1180g of product C12H18N4O4 are obtained. Calculate the percentage yield.


Ah I see. You don’t know the equation because the ins and outs of this particular reaction aren’t actually taught any more.

I’m going to tell you that 1 mole of cyclohexanone reacts with 1 mole of 2,4-DNPH to form 1 mole of C12H18N4O4 and 1 mole of water.

The question doesn’t care about the water, so ignore that and you should assume that the 2,4-DNPH is in excess because it doesn’t say how much is used and the wording suggests that all 0.8500 g of cyclohexanone are converted.
Reply 3
Thank you this is very helpful

(Original post by TypicalNerd)Ah I see. You don’t know the equation because the ins and outs of this particular reaction aren’t actually taught any more.

I’m going to tell you that 1 mole of cyclohexanone reacts with 1 mole of 2,4-DNPH to form 1 mole of C12H18N4O4 and 1 mole of water.

The question doesn’t care about the water, so ignore that and you should assume that the 2,4-DNPH is in excess because it doesn’t say how much is used and the wording suggests that all 0.8500 g of cyclohexanone are converted.

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