8. Fizzy drinks are made by adding carbon dioxide gas, preservative, colouring and flavouring to water - Scottish Highers Chemistry - Question 8 - 2022

The graph should show a decrease in yield as temperature increases because the reaction is exothermic. As temperature rises, the equilibrium shifts to favor the endothermic direction, decreasing the amount of carbon dioxide produced.

1. Calculate moles of sorbic acid:
   • Molar mass = 112 g/mol
   • Moles = mass / molar mass = 7 g / 112 g/mol = 0.0625 moles.
2. Calculate moles of potassium hydroxide:
   • Concentration = 0.5 mol/dm³, Volume = 250 cm³ = 0.250 dm³.
   • Moles = concentration × volume = 0.5 mol/dm³ × 0.250 dm³ = 0.125 moles.
3. Since the reaction consumes a 1:1 ratio of sorbic acid to potassium hydroxide, and we have 0.0625 moles of sorbic acid, it is the limiting reactant.

1. Find the amount of ammonium ferric citrate in grams:
   • 0.002% in 330 cm³ = 0.002/100 × 330 g = 0.0066 g.
2. Calculate moles:
   • Moles = mass / molar mass = 0.0066 g / 261.8 g/mol ≈ 0.0000252 moles.

Essential oils are volatile and usually aromatic, meaning they can easily evaporate and contribute to fragrance.

The compound formed is a diene or polyene, specifically a terpenoid due to its structure.

The structural formula for isoprene is:

  H  H
   \/ 
  C  =  C
  |      
  H  C  -  C  -  H
  |       
  H      H  

Zingiberene consists of 3 isoprene units.

Product X is shogaol.

1. Hydroxyl group (-OH)
2. Carbonyl group (C=O)