Calcium carbonate equilibrium pressure must exceed total atmospheric pressure of 101 kPa, which happens at 898 °C. Calcium carbonate is poorly soluble in pure water (47 mg/L at normal atmospheric CO partial pressure as shown below). The equilibrium of its solution is given by the equation (with dissolved calcium carbonate on the right): where the solubility product for [Ca] [CO] is given as anywhere from "K" = 3.7×10 to "K" = 8.7×10 at 25 °C, depending upon the data source. What the equation means is that the product of molar concentration of calcium ions (moles of dissolved Ca per liter of solution)
Calcium gluconate one-gram vial, 10 ml of 100 mg/ml (10% solution). In the United Kingdom this amount costs the NHS about 0.65 pounds. 10% calcium gluconate solution (given intravenously) is the form of calcium most widely used in the treatment of low blood calcium. This form of calcium is not as well absorbed as calcium lactate, and it only contains 0.93% (930 mg/dl) calcium ion (defined by 1 g weight solute in 100 ml of solution to make 1% solution w/v). Therefore, if the hypocalcemia is acute and severe, calcium chloride is given instead. Calcium gluconate is used as a cardioprotective agent