Final answer:
To prepare 100mL of a 0.4 M NaCl solution, one needs to calculate the number of moles needed and then convert it to grams using the molar mass of NaCl. The correct answer would be close to 2.34g, which doesn't match any of the provided options.
Step-by-step explanation:
The student has asked how much NaCl is needed to make 100mL of a 0.4 M solution. The molarity (M) of a solution is defined as the number of moles of solute per liter of solution. To calculate the mass of NaCl needed, we first need to determine the number of moles required for 100mL of a 0.4 M solution.
Moles of NaCl = Molarity of NaCl (M) × Volume of solution (L)
0.4 moles/L × 0.1 L = 0.04 moles
To convert moles of NaCl to grams, we use the formula mass of NaCl, which is 58.44 g/mol.
Mass of NaCl = Moles of NaCl × Formula mass of NaCl
0.04 moles × 58.44 g/mol = 2.3376 g
This value is not an option provided, suggesting there may be a typo in the question or the multiple choice answers, or a potential misunderstanding. The correct answer to the amount of NaCl needed according to the molarity calculation would be close to 2.34g, which is not listed as an option.