Question

A student wants to prepare 250.0 mL of 0.10 M NaCl solution. Which procedure is most appropriate? (formula Molar Mass of NaCl = 58.4 g/mol)
A) Add 5.84 g of NaCl to 250. mL of H2O
B) Add 1.46 g of NaCl to 250. mL of H2O
C) Dissolve 5.84 g of NaCl in 50 mL of H2O and dilute to 250. mL
D) Dissolve 1.46 g of NaCl in 50 mL of H2O and dilute to 250. mL

Answer 1

The correct answer is option B, that is, add 1.46 grams of NaCl to 250 milliliters of H₂O.

First there is a need to find the moles of NaCl in 250 ml of 0.10 M NaCl,

Moles of NaCl = molarity × volume = 0.10 M × (250/1000L) = 0.025 mol

The corresponding mass of NaCl is,

Mass of NaCl = moles × molar mass = 0.025 mol × 58.5 g/mol = 1.46 g

Thus, there is a need to dissolve 1.46 grams of NaCl solid into 50 ml of H₂O and dilute to 250 ml.