Carbon is also removed from the atmosphere during the process of weathering. carbon dioxide combines with water to form carbonic acid. this reacts with calcium silicate (in rocks) to produce calcium ions, bicarbonate ions and silicon dioxide (silica) the chemical equation for this reaction looks like this:

CaSIO3 + 2CO2 + H2O >>> Ca2+ + 2HCO3 + SiO2

A) Maine organisms, like molluscs, use these dissolved ions to make their shells. what compound are these shells mainly made of

Calcium Carbonate, CaCO3, which can form from Ca^+2 and CO3^-2 ions. Bicarbonate ions, HCO3^-, change to CO3^-2 ions in sea-water since sea-water is basic.

And, in the body of the mollusk, the blood is rich with Calcium ions, and bicarbonate ions. These react with blood heme-oxygen to form calcium carbonate and water. The shell material does not come from the seawater directly, it comes to the ectodemic cells in the mollusk, so the calcium carbonate shell is excreted by these cells.

http://en.wikipedia.org/wiki/Mollusc_shell

The compound that shells of Maine organisms, like mollusks, are mainly made of is calcium carbonate (CaCO3).

To determine what compound the shells of Maine organisms, like molluscs, are mainly made of, we need to understand the chemical equation provided. In the equation, it is mentioned that calcium silicate (CaSiO3) reacts with carbon dioxide (CO2) and water (H2O) to produce calcium ions (Ca2+), bicarbonate ions (HCO3-), and silicon dioxide (SiO2).

The compound that is mainly found in the shells of Maine organisms like molluscs is calcium carbonate (CaCO3).

The bicarbonate ions (HCO3-) produced in the reaction combine with calcium ions (Ca2+), derived from the weathering process, to form calcium carbonate. This calcium carbonate then precipitates and becomes the primary component of the shells.

So, the shells of Maine organisms, like molluscs, are mainly composed of calcium carbonate (CaCO3).