What is the first step in calculating the percent by weight of an element in a compound?

What is the first step in calculating the percent by weight of an element in a compound?

• A. Convert grams to moles
• B. Determine the molecular weight
• C. Calculate the volume of the solution
• D. Identify the solute in the solution

Answer: (B)

Determining the molecular weight of the compound is the essential first step in calculating the percent by weight of an element in that compound. The percent by weight is calculated using the formula: \[ \text{Percent by Weight} = \left( \frac{\text{mass of the element}}{\text{molecular weight of the compound}} \right) \times 100 \] To apply this formula effectively, the molecular weight provides the denominator, which is critical for expressing the mass of the specific element as a fraction of the entire compound's mass. Each element's atomic weight contributes to the total molecular weight, allowing for an accurate calculation of how much of the compound's weight is represented by the element of interest. While converting grams to moles or identifying solutes is valuable in various contexts, these actions do not directly contribute to the right approach to calculating the percent by weight. Furthermore, calculating the volume of the solution is typically relevant in concentration measurements rather than percent by weight calculations. Therefore, determining the molecular weight lays the necessary groundwork for achieving the correct percent by weight assessment in a compound.

Determining the molecular weight of the compound is the essential first step in calculating the percent by weight of an element in that compound. The percent by weight is calculated using the formula:

[

\text{Percent by Weight} = \left( \frac{\text{mass of the element}}{\text{molecular weight of the compound}} \right) \times 100

]

To apply this formula effectively, the molecular weight provides the denominator, which is critical for expressing the mass of the specific element as a fraction of the entire compound's mass. Each element's atomic weight contributes to the total molecular weight, allowing for an accurate calculation of how much of the compound's weight is represented by the element of interest.

While converting grams to moles or identifying solutes is valuable in various contexts, these actions do not directly contribute to the right approach to calculating the percent by weight. Furthermore, calculating the volume of the solution is typically relevant in concentration measurements rather than percent by weight calculations. Therefore, determining the molecular weight lays the necessary groundwork for achieving the correct percent by weight assessment in a compound.