Question

what is the percent by mass of oxygen in ch₃cooh (gram - formula mass = 60. g/mol)?

1. 27%
2. 32%
3. 53%
4. 60.%

Explanation:

Step1: Find moles of O in formula

In \( \text{CH}_3\text{COOH} \) (acetic acid), the formula has 2 O atoms. Molar mass of O is \( 16 \, \text{g/mol} \), so total mass of O: \( 2 \times 16 = 32 \, \text{g/mol} \).

Step2: Calculate percent by mass

Percent by mass formula: \( \frac{\text{Mass of O}}{\text{Gram - formula mass}} \times 100\% \). Substitute values: \( \frac{32}{60} \times 100\% \approx 53\% \).

Answer:

1. 53%