2.3 The wider impact of chemistry

Question 1

Define carbon neutrality

Answer 1

A chemical process such as fuel combustion does not lead to an overall increase in CO2 levels. Although combustion does generate CO2, this is off set by the fact that the fuel has absorbed the same amount of CO2 in being made by photosynthesis

Question 2

How is carbon neutrality achieved?

Answer 2

Combustible fuel sources: by replanting trees and sugar cane, to match those being burnt, so that the CO2 consumed in their photosynthesis equals or exceeds that generated by their combustion.

Renewable source: combustion of biomass

Question 3

What is biomass?

Answer 3

plant or animal material used for energy production.

Question 4

Write the general equation for combustion of biomass.

Answer 4

CH2O + O2 ⇌ CO2 + H2O

Question 5

What is solar power?

Answer 5

Capturing energy from the sun and subsequently converting it into electricity.

Question 6

What must to ensure to assess if a process is energy efficient?

Answer 6

1. Renewable raw materials
2. Saving energy: using as little energy as possible and from renewable sources
3. High atom economy: high percentage of mass of reactants ends up in product
4. Catalysts: developing better catalysts, e.g. usage of bio catalysts like enzymes
5. Toxic materials and solvents: avoid usage of toxic materials if possible.
   avoid usage of solvents, especially volatile organic compounds
6. Production of biodegradable products

Question 7

Provide a summary of green principles.

Answer 7

1. Prevent waste
2. Increase atom economy
3. Use safer methods, chemicals and solvents
4. Increase energy efficiency
5. Use renewable raw materials (feedstocks)
6. Use catalysts
7. Prevent pollution and accidents
8. Design for biodegradation