Suppose 0.500 g of sulfur combines with 1.00 g of copper. What is the empirical formula of the compound? The atomic mass of sulfur is 32.065 g and the atomic mass of copper is 63.546 g.
Convert grams to mols.
mols S = grams/atomic mass = ?
mols Cu = grams/atomic mass = ?
Now you want to find the ratio of the elements to each other with the smallest number being 1.00. The easy way to do this is to divide the smaller number by itself (thereby assuring 1.00 for that one), then divide the other number by the same small number. Round to whole numbers and that should give you the empirical formula. Post your work if you run into trouble.
To determine the empirical formula of a compound, we need to find the ratio of the elements present in the compound.
1. Begin by converting the masses of sulfur and copper into moles using their atomic masses.
Moles of sulfur = 0.500 g / 32.065 g/mol = 0.0156 mol
Moles of copper = 1.00 g / 63.546 g/mol = 0.0157 mol
2. Next, divide both moles by the smaller value to get the mole ratio between the elements.
Moles of sulfur / Moles of sulfur = 0.0156 mol / 0.0156 mol = 1
Moles of copper / Moles of sulfur = 0.0157 mol / 0.0156 mol ≈ 1.01
(Round to the nearest whole number)
3. Multiply both mole ratios by a common multiple to get whole numbers for both elements.
Multiply by 100 to simplify the ratio:
Sulfur: 1 × 100 = 100
Copper: 1.01 × 100 ≈ 101
4. The result gives us a ratio of approximately 100:101. However, we want to find the simplest whole number ratio. In this case, we can divide both numbers by their greatest common divisor (GCD), which is 1.
Simplified ratio: 100 ÷ 1 = 100
101 ÷ 1 = 101
5. Therefore, the empirical formula of the compound is S₃Cu₃.