1) Which one of the following correctly identifies the renewability of biomethane and natural gas?

Solution

2) A 65.0 g snack bar contains:
• 45.0 g of carbohydrate
• 10.0 g of protein
• 10.0 g of fats.
The total energy content per 100 g of the snack bar is closest to
A. 1.3 × 10³ J
B. 1.9 × 10³ J
C. 1.3 × 10⁶ J
D. 1.9 × 10⁶ J

Solution

3) The circular economy of a bioethanol production process could be improved by
A. increasing the fermentation temperature to accelerate the reaction rate.
B. using a new strain of yeast to produce a higher yield of ethanol from glucose.
C. developing a separate process that converts waste carbon dioxide into a useful product.
D. carrying out advanced distillation techniques to reduce energy consumption.

Solution

4)The production of bioethanol from sugar cane follows the steps shown below.

Consider the following statements:
I Oxidation occurs during fermentation.
II Enzymes catalyse only two of the steps shown.
III Glucose is a product of the hydrolysis step.

Which of the statements about the production of bioethanol is/are correct?
A. II only
B. I and II
C. I and III
D. II and III

Solution

5) Kim investigated the energy efficiency of two different fuels, propane, C₃H₈, and pure bioethanol, C₂H₅OH, for heating water. Kim placed a saucepan with 166.0 g of tap water on a portable camp stove and heated it using C₃H₈. The set-up for the experiment is shown below.

The following results were recorded.

a. Write a balanced thermochemical equation for the complete combustion of
C₃H₈. (2 marks)

Solution

b. Using item 13 of the Data Book, calculate the amount of energy released by the complete combustion of 9.0 g of C₃H₈ (M = 44.0 g mol−1 ). (2 marks)

Solution

c. i. Calculate the energy absorbed by the water in the saucepan. (2 marks )

ii. Determine the overall energy efficiency of heating the water in the saucepan.
(1 mark)

Solution

d. Kim placed all of the equipment inside a sealed container with a total air volume of 0.125 m3 and repeated the investigation. The air in the enclosure contained 21.0% v/v oxygen, O₂, at standard laboratory conditions (SLC).

9.0 g of C₃H₈ was combusted in the sealed container shown above. Determine the mass of the reactant in excess. (4 marks)

Solution

e. In another investigation, Kim found that 15.3 g of C₂H₅OH (M = 46.0 g mol−1 ) was required to produce the same change in water temperature as the 9.0 g of C₃H₈. Explain why different masses of the fuels were required to produce the same temperature change. (2 marks )

Solution