Question

How many moles of substance will we have, if we measure from 20g of these substances:

Zn, Na₂SO₄, C₆H₁₂O₆, S₈, Cu(NO₃)₂, CaCl₂ × 2H₂O

Answer 1

To calculate the number of moles in a sample, divide its mass by its molar mass. For the given substances, the number of moles are: Zn - 0.31 mol, Na₂SO₄ - 0.14 mol, C₆H₁₂O₆ - 0.11 mol, S₈ - 0.078 mol, Cu(NO₃)₂ - 0.107 mol, CaCl₂ × 2H₂O - 0.27 mol.

Step-by-step explanation:

To calculate the number of moles in a sample, we need to divide the mass of the sample by its molar mass. Here are the calculations for the given substances:

• Zn: 20 g ÷ 65.4 g/mol = 0.31 mol
• Na₂SO₄: 20 g ÷ 142 g/mol = 0.14 mol
• C₆H₁₂O₆: 20 g ÷ 180 g/mol = 0.11 mol
• S₈: 20 g ÷ 256 g/mol = 0.078 mol
• Cu(NO₃)₂: 20 g ÷ 187.6 g/mol = 0.107 mol
• CaCl₂ × 2H₂O: 20 g ÷ (40.1 g/mol + 2(35.5 g/mol) + 2(18.0 g/mol)) = 0.27 mol