Which of the following best describes how to calculate the percent by mass of each element in a compound?

• A. Divide the number of atoms of each element by the total number of atoms in the compound, then multiply by 100%.
• B. Add the atomic masses of all elements and divide by the number of elements, then multiply by 100%.
• C. Divide the molar mass of the compound by the mass of each element, then multiply by 100%.
• D. Divide the mass of each element in one mole of the compound by the molar mass of the compound, then multiply by 100%.

Answer: (D)

Verified step by step guidance

1. Understand that percent by mass of an element in a compound represents the fraction of the compound's total mass contributed by that element, expressed as a percentage.
2. Calculate the mass of each element in one mole of the compound by multiplying the number of atoms of that element by its atomic mass (from the periodic table).
3. Determine the molar mass of the compound by summing the masses of all atoms of all elements present in one mole of the compound.
4. Divide the mass of the element (from step 2) by the total molar mass of the compound (from step 3) to find the fraction of the compound's mass due to that element.
5. Multiply the fraction obtained in step 4 by 100% to convert it to a percent by mass for that element.