Answer:
The percent by mass of a compound is determined by comparing the mass of a specific element in the compound to the total mass of the compound. This demonstrates the law of definite proportions.
To calculate the percent by mass of an element in a compound, you need to follow these steps:
Identify the chemical formula of the compound, which specifies the types and quantities of atoms of each element within the compound.
Determine the atomic mass of the element you want to find the percent for from the periodic table, typically given in atomic mass units (amu) or grams per mole (g/mol).
Determine how many atoms of the element are present in one molecule of the compound. This information is indicated by the subscripts in the chemical formula.
Calculate the molar mass of the entire compound by adding up the atomic masses of all the elements in the compound, taking into account their respective subscripts.
Determine the mass of the specific element you're interested in within one mole of the compound by multiplying the element's atomic mass by the number of atoms of that element in one molecule of the compound.
Finally, compute the percent by mass of the element using the following formula:
Percent by Mass = (Mass of Element / Molar Mass of Compound) × 100%
Step-by-step explanation:
This calculation enables you to express the proportion of the total mass of a compound that is attributed to a particular element, illustrating the law of definite proportions, which asserts that a given compound always contains the same elements in fixed mass ratios.