Multiple Choice
An unknown compound contains only carbon, hydrogen, and oxygen. Using combustion analysis, you burned 19.31 mg of the sample and collected 17.96 mg of H2O and 43.89 mg of CO2. What is the empirical formula of this compound?
3. Chemical Reactions
Empirical Formula
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If 0.500 mol of copper combines with 0.250 mol of sulfur, what is the empirical formula of the copper sulfide product?
A
Cu5S5
B
CuS
C
CuS2
D
Cu2S
Verified step by step guidance1
Determine the mole ratio of copper to sulfur by dividing the number of moles of each element by the smallest number of moles present. In this case, divide both 0.500 mol of copper and 0.250 mol of sulfur by 0.250 mol.
Calculate the ratio for copper: \( \frac{0.500 \text{ mol Cu}}{0.250 \text{ mol}} = 2 \).
Calculate the ratio for sulfur: \( \frac{0.250 \text{ mol S}}{0.250 \text{ mol}} = 1 \).
Use the mole ratios to write the empirical formula. The ratio of copper to sulfur is 2:1, which means there are 2 copper atoms for every sulfur atom.
Write the empirical formula based on the ratio: \( \text{Cu}_2\text{S} \).
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