What mass of ethanol is obtained when 5.68 g of carbon dioxide is produced during fermentation, at 25°C and 100 kPa? (A) 2.95 g (B) 5.95 g (C) 33.6 g (D) 147.2 g - HSC - SSCE Chemistry - Question 15 - 2010 - Paper 1

The fermentation process can be simplified with the equation:

$C_6H_{12}O_6 \rightarrow 2C_2H_5OH + 2CO₂$

From the stoichiometry, 1 mole of glucose produces 2 moles of ethanol and 2 moles of CO₂. Therefore, from the moles of CO₂ produced, we can deduce:

$n_{C_2H_5OH} = \frac{1}{2} n_{CO₂} = \frac{1}{2} \times 0.129 = 0.0645\text{ moles of ethanol}$

Now, calculate the mass of ethanol using its molar mass (approximately 46.07 g/mol):

$m_{C_2H_5OH} = n_{C_2H_5OH} \times M_{C_2H_5OH}$

Substituting in the values:

$m_{C_2H_5OH} = 0.0645 \times 46.07 \approx 2.97 ext{ g}$

Thus, rounding off, the mass of ethanol produced is approximately 3.00 g.