Learning Objectives

Coral Bleaching

CO₂(g) traps heat in the atmosphere, raising the temperature of the ocean, this causes the expulsion of algae (zooxanthellae) from the coral which feeds upon it → zooxanthellae are what give coral its colour, a loss of zooxanthellae causes coral to go white (coral bleaching)

Ocean Acidification

Carbon Emissions increase the concentration of atmospheric CO₂ (g) → ⇒ this results in an increase of CO₂ absorption in the ocean as the equilibrium of CO₂ (g) ⇌ CO₂ (aq) shifts right, increasing the concentration of CO₂ (aq)
CO₂ (aq) is used in the production of carbonic acid H_2CO_3→ $\sf CO_{2 \space (aq)}\space + \space H_2O_{\space (l)} \leftrightarrows H_2CO_{3 \space (aq)}$→ $\sf\small \uparrow [CO_{2 \space (aq)}]$ results in the equilibrium shifting right, therefore $\sf\small \uparrow [H_2CO_{3}]$
$H_2CO_3$ is used in the production of Hydronium ions ($H_3O^+$)⇒ 1st ionisation: $H_2CO_{3\space(aq)}+H_2O_{\space(l)} \leftrightarrows H_3O^+{\space(aq)}\space + \space HCO{3\space(aq)}$⇒ 2nd ionisation: $HCO^-{3\space(aq)}+H_2O{\space(l)} \leftrightarrows H_3O^+{\space(aq)}\space + \space CO^-{3\space(aq)}$→ $\sf\small \uparrow [H_2CO_{3 \space (aq)}]$ ⇒ equilibrium shifts right $\sf\small \uparrow [H_3O^+_{\space (aq)}]$⇒ $H_3O^+$ decreases the pH of the ocean (acidifying it)⇒ increased acidity is dangerous for ocean inhabitants → fish die

Ocean Decalcification

Reefs and crustaceans rely on limestone ($CaCO_{3\space (s)}$) to form their structure/shell⇒ limestone is partially insoluble in water: $Ca^{\space2+}{\space(aq)}+CO^-{2\space(aq)} \leftrightarrows \space CaCO_{3\space(s)}$$\sf\small \uparrow [H_3O^+{ \space (aq)}]$ ⇒ favours the reverse reaction for $HCO^-{3\space(aq)}+H_2O_{\space(l)} \leftrightarrows H_3O^+{\space(aq)}\space + \space CO^-{3\space(aq)}$⇒ this consumes $CO^-_{3\space(aq)}$ decreasing its concentration in the water⇒ $\uparrow CO^-{3\space(aq)}$ ⇒ equilibrium shifts right for $Ca^{\space2+}{\space(aq)}+CO^-{2\space(aq)} \leftrightarrows \space CaCO{3\space(s)}$ therefore $\downarrow [CaCO_{3\space(s)}]$ (decalcification)⇒ this is harmful to the ecosystem as such species are unable to survive, crustaceans unable to form shells, and reefs unable to form their structure and the species which rely on such organisms for shelter or for nutrition are also impaired

Reefs and crustaceans rely on limestone ($CaCO_{3\space (s)}$) to form their structure/shell⇒ limestone is partially insoluble in water: $Ca^{\space2+}{\space(aq)}+CO^-{2\space(aq)} \leftrightarrows \space CaCO_{3\space(s)}$
$\sf\small \uparrow [H_3O^+{ \space (aq)}]$ ⇒ favours the reverse reaction for $HCO^-{3\space(aq)}+H_2O_{\space(l)} \leftrightarrows H_3O^+{\space(aq)}\space + \space CO^-{3\space(aq)}$⇒ this consumes $CO^-_{3\space(aq)}$ decreasing its concentration in the water⇒ $\uparrow CO^-{3\space(aq)}$ ⇒ equilibrium shifts right for $Ca^{\space2+}{\space(aq)}+CO^-{2\space(aq)} \leftrightarrows \space CaCO{3\space(s)}$ therefore $\downarrow [CaCO_{3\space(s)}]$ (decalcification)⇒ this is harmful to the ecosystem as such species are unable to survive, crustaceans unable to form shells, and reefs unable to form their structure and the species which rely on such organisms for shelter or for nutrition are also impaired