Question

Which solution below contains the highest total quantity (moles) of dissolved sodium ions?

A) 100. mL of 4.0 M NaCl
B) 75.0 mL of 3.0 M Na₂SO₄
C) 50.0 mL of 8.0 M NaOH
D) 50.0 mL of 2.0 M Na₃PO₄
E) none of the above

Answer 1

Solution B, which is 75.0 mL of 3.0 M Na2SO4, contains the highest total quantity of dissolved sodium ions with a total of 0.450 moles of Na+.

Step-by-step explanation:

To determine which solution contains the highest total quantity of dissolved sodium ions, we need to calculate the moles of sodium ions in each solution.

Solution A: 100.0 mL of 4.0 M NaCl

Since NaCl produces one mole of sodium ions (Na+) for each mole of NaCl dissolved, the total moles of Na+ are:

4.0 moles/L × 0.100 L = 0.400 moles of Na+

Solution B: 75.0 mL of 3.0 M Na2SO4

Na2SO4 produces two moles of Na+ for each mole of Na2SO4 dissolved. The total moles of Na+ are:

3.0 moles/L × 0.075 L × 2 = 0.450 moles of Na+

Solution C: 50.0 mL of 8.0 M NaOH

Since NaOH produces one mole of Na+ for each mole of NaOH dissolved, the total moles of Na+ are:

8.0 moles/L × 0.050 L = 0.400 moles of Na+

Solution D: 50.0 mL of 2.0 M Na3PO4

Na3PO4 produces three moles of Na+ for each mole of Na3PO4 dissolved. The total moles of Na+ are:

2.0 moles/L × 0.050 L × 3 = 0.300 moles of Na+

The solution with the highest total moles of dissolved Na+ is Solution B, which has 0.450 moles of Na+.

Answer 2

Option B, a 75.0 mL solution of 3.0 M Na2SO4, contains the highest total quantity of dissolved sodium ions due to each sodium sulfate molecule providing two sodium ions, resulting in 0.45 moles of Na+ ions.

Step-by-step explanation:

To determine which solution contains the highest total quantity (moles) of dissolved sodium ions, we need to calculate the number of moles of sodium per unit volume for each solution and then multiply by the volume to find the total moles of sodium ions in each solution.

For Option A (100. mL of 4.0 M NaCl), 100 mL of a 4.0 M NaCl solution contains 0.4 moles of NaCl, equating to 0.4 moles of Na+ ions since each formula unit of NaCl contributes one sodium ion.

For Option B (75.0 mL of 3.0 M Na₂SO₄), 75 mL of a 3.0 M Na₂SO₄ solution contains 0.225 moles of Na₂SO₄, which results in 0.45 moles of Na+ ions because each formula unit of Na₂SO₄ contains two sodium ions.

For Option C (50.0 mL of 8.0 M NaOH), 50 mL of an 8.0 M NaOH solution contains 0.4 moles of NaOH, equating to 0.4 moles of Na+ ions.

For Option D (50.0 mL of 2.0 M Na₃PO₄), 50 mL of a 2.0 M Na₃PO₄ solution contains 0.1 moles of Na₃PO₄, which results in 0.3 moles of Na+ ions because each formula unit of Na₃PO₄ contains three sodium ions.

After analyzing all options, we can conclude that Option B contains the highest total quantity (moles) of dissolved sodium ions. The total quantity of sodium ions is highest in the Na₂SO₄ solution due to it providing two sodium ions per formula unit, and the adequate volume and molarity amplify this effect.