What happens when Co2 gas is increase about Temperature
Increase in co2 production through fossil fuels hence increase in T global
hence ocean T decrease
Affect from CO2 g —> CO2 Aq
More in atmosphere hence increase in concentration of CO2 aq in oceans as more is dissolved in oceans
Explain decreasing pH
CO₂(g) ⇌ CO₂(aq)
CO₂(g) → CO₂(aq) dissolves in H₂O
CO₂(g) + H₂O(l) ⇌ H₂CO₃(aq)
H₂CO₃ ⇌ HCO₃⁻ + H⁺
HCO₃⁻ ⇌ CO₃²⁻ + H⁺
Ca²⁺ + CO₃²⁻⇌ CaCO₃(s)
Increase in atmospheric carbon dioxide levels leads to increased dissolved carbon dioxide in ocean which shifts the equilibrium position to the right in equation 1. Hence, as the carbonic acid concentration increases, the equilibrium shifts to the right in equation 2 which increases the H plus concentration. Hence, as HCO3 minus increases as shown in equation 2, the equilibrium in equation 3 shifts to the right which increases the H plus concentration. Hence, increased hydrogen ion concentration results in decreased ocean pH.
Explain decreasing in CaCO3 solid
CO₂(g) ⇌ CO₂(aq)
CO₂(g) → CO₂(aq) dissolves in H₂O
CO₂(g) + H₂O(l) ⇌ H₂CO₃(aq)
H₂CO₃ ⇌ HCO₃⁻ + H⁺
HCO₃⁻ ⇌ CO₃²⁻ + H⁺
Ca²⁺ + CO₃²⁻⇌ CaCO₃(s)
As the H+ concentration increases, hence the equilibrium position in equation 4 will shift to the right, hence favoring the forward reaction, hence decreasing the availability of calcium carbonate solid as it’s being consumed, hence reducing its amount hence the shells become weaker and vulnerable to predators.
2018 WATP Q27 sem 1
Explain how higher atmospheric carbon dioxide levels cause a decrease in ocean pH, whereas the calcium carbonate present in sediment can counteract this to increase ocean pH.
Also write all equations
an increase in atmospheric CO2 will increase the concentration of dissolved CO2, carbonic acid and H+ in ocean water (as shown in diagram)
- this lowers the pH, since pH = -log [H+]
- the CaCO3 present in sediment can dissolve in water, increasing the concentration of CO32- (as shown in the diagram)
- this CO32- can react with the H+ in the ocean water, (forming HCO3- ) and thereby increasing pH
