30) What is the % by mass of sodium chloride in an aqueous solution that is 239 M and has a density of 1.01g/mL A) 2.36 B) 13.8 C) 7.83 D) 140. E) 19.6 Answer: B

To find the percentage by mass of sodium chloride in the aqueous solution, we need to follow these steps:<br /><br />1. Calculate the mass of sodium chloride in 1 liter of the solution.<br />2. Calculate the total mass of 1 liter of the solution.<br />3. Use the formula for percentage by mass: (mass of solute / total mass of solution) * 100.<br /><br />Given:<br />- Molarity (M) = 239 M<br />- Density = 1.01 g/mL<br /><br />First, let's calculate the mass of sodium chloride in 1 liter of the solution:<br /><br />Mass of sodium chloride = Molarity * Molar mass of sodium chloride<br />Molar mass of sodium chloride (NaCl) = 58.44 g/mol<br />Mass of sodium chloride = 239 M * 58.44 g/mol = 13,976.16 g<br /><br />Next, let's calculate the total mass of 1 liter of the solution:<br /><br />Density = 1.01 g/mL<br />Total mass of 1 liter of solution = Density * Volume<br />Total mass of 1 liter of solution = 1.01 g/mL * 1000 mL = 1010 g<br /><br />Finally, let's calculate the percentage by mass of sodium chloride:<br /><br />Percentage by mass = (Mass of sodium chloride / Total mass of solution) * 100<br />Percentage by mass = (13,976.16 g / 1010 g) * 100 ≈ 13.8%<br /><br />Therefore, the correct answer is B) 13.8.