The molar mass of sodium carbonate is 2(23) + 12 + 3(16) = 106 g/mol. 0.50 moles of sodium carbonate corresponds to 0.5 mol × 106 g/mol = 53 g of Na2CO3. In 0.50 m sodium carbonate solution, 0.5 mol of sodium carbonate is present in 1000 g of water. In 0.50 M sodium carbonate solution, 0.5 moles of sodium carbonate is present in 1 L of solution.