A student weighs out 635.94 g Na2CO3 and it dissolves in it 2.0 L water whats its molarity

There are a number of ways to express concentration of a solution. This includes molarity. Molarity is expressed as the number of moles of solute per volume of the solution. We calculate as follows:

Molarity = 635.94 g Na2CO3 (1 mol / 105.99 g) / 2.0 L = 3 mol / L = 3 M