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In order to complete the lab, a 500 mL solution of 0.25 M potassium oxide was required. What mass of potassium oxide was used? Question 2 options: 6.89 g 25.2 g 0.125 g 47.1 g 11.8 g

Question

In order to complete the lab, a 500 mL solution of 0.25 M potassium oxide was required. What mass of potassium oxide was used?

Question 2 options:

6.89 g

25.2 g

0.125 g

47.1 g

11.8 g

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Solution

To determine the mass of potassium oxide (K₂O) required to prepare a 500 mL solution of 0.25 M, follow these steps:

  1. Calculate the number of moles of K₂O needed:

    • Molarity (M) = moles of solute / liters of solution
    • Given: Molarity (M) = 0.25 M, Volume (V) = 500 mL = 0.5 L
    • Moles of K₂O = Molarity × Volume = 0.25 M × 0.5 L = 0.125 moles

  2. Determine the molar mass of K₂O:

    • Potassium (K) has an atomic mass of approximately 39.1 g/mol
    • Oxygen (O) has an atomic mass of approximately 16.0 g/mol
    • Molar mass of K₂O = 2 × 39.1 g/mol + 16.0 g/mol = 78.2 g/mol + 16.0 g/mol = 94.2 g/mol

  3. Calculate the mass of K₂O required:

    • Mass = moles × molar mass
    • Mass of K₂O = 0.125 moles × 94.2 g/mol = 11.775 g

Therefore, the mass of potassium oxide used is approximately 11.8 g.

This problem has been solved

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