5. pH and Ocean Acidification Flashcards
Define pH and its concentration.
pH of a solution is a measure of its hydrogen ion concentration [H+]. The more hydrogen ion concentration the solution has, the more acidic it is. Hence, if it has a low hydrogrn ion concentration, it is an alkaline solution.
pH is defined as the negative logarithm of:
How do you find the dissociation constant of water Kw?
What is the formula to find [H+]?
How do you find pOH?
pOH = -log [OH-]
When CO2 reacts with water, H2O, to form:
carbonic acid H2CO3
What is the equation for when carbon dioxide reacts with water?
Carbonic acid dissolves quickly to form H+ ion and bicarbonate. Show this equation.
Sewater has a good buffering system. carbonate is produced by the ocean to neutralise the acids, forming more bicarbonate.
Show this equation
However, as more and more CO2 is produced anthropogenically, more and more carbonate ions are need to mop up the H+ ions. In time the buffering system would run out of carbonate.
The problem is that carbonate ions are also being used by shellfish to create their shells.
Show the equation for the shellfish to create their shells.
Explain why calcium carbonate, the chemical animal cells are made of, becomes more soluble as pH drops. Explain using the three main equations used. (very Long)
As CO2 enters the ocean, it reacts with water to produce carbonic acid. This then dissolves in the water to produce HCO3 and H+ ions.
With an increase in H+ ions, the pH becomes more acidic. The ocean will try to regulate the pH by neutralising the H+ ions using CO3- (carbonate ions).
The carbonate ions come from coral and shellfish breaking down. If the pH continues to drop, we need more carbonate to ‘mop’ up the H+ ions, meaning more and more shellfish continue to dissolve. The more pH drops, the more soluble the shellfish become.
