Question

The mussel shells are eroding because the ocean is too acidic. More acidic oceans dissolve CaCO3 faster and change them into HCO3-. There are 3 possible ways to help reduce mussel shell erosion bydisrupting the equilibrium. Choose the condition that you think will reduce mussel shell erosion.
Form a hypothesis and explain how you think this change will help.

Answer 1

This problem is providing information about possible causes whereby mussel shells are being eroded due to the acidity in the ocean. In such a way, it claims that more acidic oceans dissolve calcium carbonate in a faster way and produce hydrogen carbonate ions, and thus, a feasible explanation is required as well as a hypothesis according to the following choices:

a. Lower CO₂; this reduces the H₂CO₃ and increases the pH.

b. Add CO₃²⁻: this will add base and increase its concentration.

c. Add Ca²⁺: this will increase the precipitation rate of calcium carbonate (correct choice).

Equilibrium equations:

At first instance, we should recall the equilibrium equations that take place when acidic oceans dissolve calcium carbonate in a faster way:

$CaCO_3(s)\rightleftharpoons Ca^{2+}(aq)+CO_3^{2-}(aq)\\\\CO_3^{2-}(aq)+H^+(aq)\rightleftharpoons HCO_3^-(aq)$

$CO_2(g)+H_2O(l)\rightleftharpoons H_2CO_3(aq)$

Shifts from equilibrium:

Where we can see that the first choice is thoroughly discarded as the addition of CO₂ actually increases the ionizable carbonic acid (acidity). Moreover, the addition of CO₃²⁻ may also lead to the formation of more protons-releasing carbonic acid which also contributes to the acidity of the ocean.

Hypothesis:

Thereby, the correct condition that, for sure, contributes to the preservation of mussel shells will be the addition of Ca²⁺ and the hypothesis will be that it shifts the equilibrium towards the formation of more CaCO₃, the active compound in these shells.

Learn more:

• Acidity in oceans: brainly.com/question/9751926
• Solubility equilibrium: brainly.com/question/10760976