You dissolve 15.49 g of sodium chloride in 500 mL of water, what is the molarity of sodium cations in the solution as moles per litre?

Sure, here are the steps to calculate the molarity of sodium cations in the solution:

1. First, we need to convert the mass of sodium chloride (NaCl) into moles. The molar mass of NaCl is approximately 58.44 g/mol. So, we divide the given mass by the molar mass:

   15.49 g / 58.44 g/mol = 0.265 moles of NaCl

2. Sodium chloride dissociates completely in water to give sodium ions (Na+) and chloride ions (Cl-). So, the number of moles of Na+ is equal to the number of moles of NaCl, which is 0.265 moles.

3. Next, we convert the volume of the solution from milliliters to liters. 500 mL is equal to 0.5 L.

4. Finally, we calculate the molarity (M) of the solution by dividing the number of moles of solute by the volume of the solution in liters:

   M = 0.265 moles / 0.5 L = 0.53 M

So, the molarity of sodium cations in the solution is 0.53 moles per liter.