Evaporation is the process by which water changes from a liquid to a gas or vapor. Evaporation is the primary pathway that water moves from the liquid state back into the water cycle as atmospheric water vapor.
Molarity is defined as the number of moles of solute in 1 L of solution
the mass of sodium acetate added - 12.0 g
molar mass of sodium acetate - 82 g/mol
number of moles = mass present / molar mass
number of moles of sodium acetate added = 12.0 g / 82 g/mol = 0.146 mol
the number of moles in 250.0 mL - 0.146 mol
therefore number of moles in 1000 mL - 0.146 mol / 250.0 mL x 1000 mL/L = 0.584 mol
there are 0.584 mol in 1 L - 0.584 mol/L
the molarity of sodium acetate is 0.584 M