Four Dioralyte sachets are dissolved in 200 mL of water each. If each sachet contains 300 mg of sodium, how many millimoles of sodium ions are consumed in total when four sachets are used (nearest millimole)?

Four Dioralyte sachets are dissolved in 200 mL of water each. If each sachet contains 300 mg of sodium, how many millimoles of sodium ions are consumed in total when four sachets are used (nearest millimole)?

• A. 52 millimoles
• B. 26 millimoles
• C. 104 millimoles
• D. 13 millimoles

Answer: (A)

The key idea is converting mass of sodium to moles using its molar mass. Each sachet provides 300 mg of sodium, so four sachets contain 1200 mg, which is 1.2 g of sodium. Moles of sodium = mass / molar mass = 1.2 g / 23.0 g/mol ≈ 0.0522 mol. Converting to millimoles gives 0.0522 mol × 1000 = 52.2 mmol, rounds to 52 mmol.

The key idea is converting mass of sodium to moles using its molar mass. Each sachet provides 300 mg of sodium, so four sachets contain 1200 mg, which is 1.2 g of sodium. Moles of sodium = mass / molar mass = 1.2 g / 23.0 g/mol ≈ 0.0522 mol. Converting to millimoles gives 0.0522 mol × 1000 = 52.2 mmol, rounds to 52 mmol.