Question

What is the percentage yield when 7g of ethene produces 6g of ethanol? Mr (ethene) = 28 and mr (ethanol) = 46

Answer 1

Answer : The percent yield of ethanol is, 52.17%

Solution :

First we have to calculate the moles of ethene.

$\text{Moles of ethene}=\frac{\text{Mass of ethene}}{\text{Molar mass of ethene}}=\frac{7g}{28g/mole}=0.25moles$

Now we have to calculate the moles of ethanol.

The balanced chemical reaction will be,

$H_2C=CH_2+H_2O\rightarrow H_3C-CH_2OH$

This reaction occurs in the presence of water.

From the balanced reaction, we conclude that

As, 1 mole of ethene react to give 1 mole of ethanol

So, 0.25 mole of ethene react to give 0.25 mole of ethanol

Now we have to calculate the mass of ethanol.

$\text{Mass of ethanol}=\text{Moles of ethanol}\times \text{Molar mass of ethanol}$

$\text{Mass of ethanol}=(0.25mole)\times (46g/mole)=11.5g$

The theoretical yield of ethanol = 11.5 g

The experimental yield of ethanol = 6 g

Now we have to calculate the percent yield of ethanol.

$\%\text{ yield of ethanol}=\frac{\text{Actual yield of ethanol}}{\text{Theoretical yield of ethanol}}\times 100=\frac{6g}{11.5g}\times 100=52.17\%$

Therefore, the percent yield of ethanol is, 52.17%