What is the molarity of 5.0 L of a solution containing 200. g of dissolved CaCO3?
The molarity of a solution in which a particular compound is dissolved is defined as the number of moles of the compound dissolved per liter of the solution.
Here we have 5.0 L of solution which has 200 g of CaCO3 dissolved in it. The molar mass of CaCO3 is 100.0869 g/mol. This can be taken as 100 g/mol. approximately.
200 g of CaCO3 is 200/100 = 2 moles of CaCO3.
As the 2 moles of CaCO3 is dissolved in 5 L of the solution, the resulting molarity is given by 2/5 = 0.4 mol/liter.