Question

calculate the percent composition by mass of chromium in the fictional compound shown below. include the units, but do not write the chemical formula. round the answer to 3 significant figures. \\( v_9cr_3s_5 \\) chromium =

Explanation:

Step1: Find molar masses of elements

Molar mass of V: \( 50.94\space g/mol \), Cr: \( 52.00\space g/mol \), S: \( 32.07\space g/mol \)

Step2: Calculate total mass of Cr

In \( V_9Cr_3S_5 \), moles of Cr = 3. Mass of Cr = \( 3 \times 52.00 = 156.0\space g \)

Step3: Calculate molar mass of compound

Mass of V: \( 9 \times 50.94 = 458.46\space g \)
Mass of S: \( 5 \times 32.07 = 160.35\space g \)
Total molar mass = \( 458.46 + 156.0 + 160.35 = 774.81\space g/mol \)

Step4: Calculate percent composition of Cr

Percent composition = \( \frac{\text{Mass of Cr}}{\text{Total molar mass}} \times 100 = \frac{156.0}{774.81} \times 100 \approx 20.1\% \)

Answer:

\( 20.1\% \)