Calcium dissolved in the ocean is used by marine organ - isms to form CaCO3 (s) in skeletons and shells. When the organisms die, their remains fall to the bottom. The amount of calcium carbonate that can be dissolved in seawater depends on the pressure. At great depths, where the pressure exceeds about 414 atm, the shells slowly.

h = 1.403x10⁴ ft

Explanation:

first, the missing part of the question is the following:

"This reaction prevents all the Eart h's calcium from being tied up as insoluble CaCO3 (s) at the bottom of the sea. Estimate the depth (in feet) of water that exerts a pressure great enough to dissolve seashells."

Now, to calculate the depth in feet, of the water, we need to use the correct expression to this. As we are talking about the sea pressure and depth we need to use the hydrostatic pressure expression which is:

P = dgh (1)

Where:

P: Pressurre (In Pa or Kg/m. s²)

g: gravity acceleration (m/s²) = 9.81 m/s²

d: density of the water (g/mL or kg/m³) = 1000 kg/m³

h: height or depth (in m, which later will be converted to feet).

From (1), we can solve for h:

h = P/dg (2)

So, before we put the values in the expression, we need to convert the units of pressure to Pa:

P = 414 atm * 1.01325 Pa = 4.195x10⁷ Pa (1 Pa = 1 kg/m. s²)

Now, replacing the values in (2):

h = 4.195x10⁷ kg/m. s² / 9.81 m/s² * 1000 kg/m³ (All units but meters, cancels out)

h = 4,276.25 m

But we need this value in ft, and in 1 m we have 3.28 ft so:

h = 4,276.25 * 3.28

h = 14,026.1 ft or 1.403x10⁴ ft