Multiple Choice
Sterling silver is an alloy commonly used in jewelry and contains silver and other metals. What is the mass percent of silver in sterling silver?
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3. Chemical Reactions
Mass Percent
Multiple Choice
An oxide of iron has the formula Fe_3O_4. What is the mass percent of iron in Fe_3O_4?
A
55.8%
B
44.8%
C
65.0%
D
72.4%
Verified step by step guidance1
Identify the chemical formula of the compound, which is Fe_3O_4. This means the compound contains 3 atoms of iron (Fe) and 4 atoms of oxygen (O).
Find the atomic masses of the elements involved: iron (Fe) has an atomic mass of approximately 55.8 g/mol, and oxygen (O) has an atomic mass of approximately 16.0 g/mol.
Calculate the total molar mass of Fe_3O_4 by multiplying the number of atoms of each element by their atomic masses and then summing these values: \(\text{Molar mass} = 3 \times 55.8 + 4 \times 16.0\).
Calculate the total mass of iron in one mole of Fe_3O_4 by multiplying the number of iron atoms by the atomic mass of iron: \(\text{Mass of Fe} = 3 \times 55.8\).
Determine the mass percent of iron in Fe_3O_4 using the formula: \(\text{Mass \% Fe} = \left( \frac{\text{Mass of Fe}}{\text{Molar mass of Fe}_3\text{O}_4} \right) \times 100\%\).
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