What is the mass of:

• 0.5 mole of water molecules
• 10 moles of sodium sulphite (Na₂SO₃)?

To find the mass of a substance, you can use the formula:

Mass Calculation Formula

Mass = Number of Moles × Molar Mass

Mass of Water (H₂O)

First, let's calculate the mass of 0.5 moles of water:

• Molar mass of water (H₂O) = 2(1.01 g/mol for H) + 16.00 g/mol for O = 18.02 g/mol
• Mass of 0.5 moles = 0.5 moles × 18.02 g/mol = 9.01 grams

Mass of Sodium Sulphite (Na₂SO₃)

Next, we calculate the mass of 10 moles of sodium sulphite:

• Molar mass of sodium sulphite (Na₂SO₃) = 2(22.99 g/mol for Na) + 32.07 g/mol for S + 3(16.00 g/mol for O) = 126.05 g/mol
• Mass of 10 moles = 10 moles × 126.05 g/mol = 1260.5 grams

Summary of Results

The mass of 0.5 moles of water is 9.01 grams, and the mass of 10 moles of sodium sulphite is 1260.5 grams.