Multiple Choice
Which of the following best represents the mass percent of Earth's water that is fresh water?
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3. Chemical Reactions
Mass Percent
Multiple Choice
Morphine has the molecular formula C17H19NO3. What is the mass percent of oxygen in morphine?
A
13.5%
B
21.2%
C
16.0%
D
9.8%
Verified step by step guidance1
Identify the molecular formula of morphine: C17H19NO3. This tells us the number of atoms of each element in one molecule.
Calculate the molar mass of morphine by summing the atomic masses of all atoms: multiply the number of each type of atom by its atomic mass (C = 12.01 g/mol, H = 1.008 g/mol, N = 14.01 g/mol, O = 16.00 g/mol) and add them together using the formula: \(\text{Molar mass} = 17 \times 12.01 + 19 \times 1.008 + 1 \times 14.01 + 3 \times 16.00\).
Calculate the total mass of oxygen atoms in the molecule by multiplying the number of oxygen atoms by the atomic mass of oxygen: \(3 \times 16.00\) g/mol.
Determine the mass percent of oxygen by dividing the total mass of oxygen by the molar mass of morphine and then multiplying by 100 to convert to a percentage: \(\text{Mass \% O} = \left( \frac{3 \times 16.00}{\text{Molar mass of morphine}} \right) \times 100\).
Interpret the result to find the mass percent of oxygen in morphine, which corresponds to one of the given answer choices.
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