Over the last 50 years, scientists have recorded increases in the following: - the amount of fossil fuels burnt - atmospheric carbon dioxide levels - average global air temperature and ocean temperature - the volume of carbon dioxide dissolved in the oceans - HSC - SSCE Chemistry - Question 30 - 2018 - Paper 1

1. Combustion of Fossil Fuels: The burning of fossil fuels, such as octane, releases CO₂ into the atmosphere and contributes to increased atmospheric CO₂ levels. For example:

   $$$$

ightarrow 8 ext{CO}_2 + 9 ext{H}_2 ext{O}$$

This reaction not only increases the concentration of CO₂ in the air but also elevates temperatures due to the heat released.

2. Equilibrium in Water: CO₂ can also dissolve in oceans, leading to the following equilibrium:

   $$$$

ightleftharpoons ext{H}_2 ext{CO}_3(aq)$$

This reaction is crucial since it helps regulate the concentration of CO₂ in both the atmosphere and oceans. As atmospheric CO₂ levels increase, the equilibrium shifts.

3. Le Chatelier's Principle: According to Le Chatelier's Principle, if conditions change (like increased temperature or pressure), the equilibrium will adjust to counteract the change. Therefore, rising temperatures can reduce the solubility of CO₂ in sea water, leading to even higher levels of CO₂ in the atmosphere.

4. Observations of Scientists: Scientists have observed that rising global temperatures lead to increased ocean temperatures. This means the oceans will hold less dissolved CO₂, which exacerbates the overall increase of this greenhouse gas in the atmosphere.