Multiple Choice
A compound is found to be 66.6% carbon and 33.4% hydrogen by mass. What is the empirical formula of this compound?
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3. Chemical Reactions
Empirical Formula
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What is the empirical formula of a compound that contains 49.4% K, 20.3% S, and 30.3% O by mass?
A
K2SO3
B
KSO3
C
K2SO4
D
KSO4
Verified step by step guidance1
Step 1: Assume you have 100 grams of the compound, so the mass of each element corresponds directly to the given percentages: 49.4 g K, 20.3 g S, and 30.3 g O.
Step 2: Convert the mass of each element to moles by dividing by their respective atomic masses: potassium (K) = 39.10 g/mol, sulfur (S) = 32.07 g/mol, and oxygen (O) = 16.00 g/mol. Use the formula: \(\text{moles} = \frac{\text{mass}}{\text{atomic mass}}\).
Step 3: Determine the simplest whole number mole ratio by dividing all mole values by the smallest number of moles calculated among the elements.
Step 4: If any mole ratios are not whole numbers, multiply all ratios by the smallest factor that converts them into whole numbers to get the empirical formula subscripts.
Step 5: Write the empirical formula using the whole number mole ratios as subscripts for each element symbol, resulting in the formula that represents the simplest ratio of atoms in the compound.
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