Question

calculate the percent composition by mass of carbon in the fictional compound below. include the units, but do not write the chemical formula. round the answer to 3 significant figures. \\(\ce{nh_9(c_8h_3o_2)_3}\\) carbon =

Explanation:

Step1: Calculate moles of C

In \( \text{NH}_9(\text{C}_8\text{H}_3\text{O}_2)_3 \), moles of C: \( 8\times3 = 24 \)
Molar mass of C: \( 12.01\ \text{g/mol} \)
Mass of C: \( 24\times12.01 = 288.24\ \text{g} \)

Step2: Calculate molar mass of compound

• Molar mass of N: \( 14.01\ \text{g/mol} \), moles: 1, mass: \( 14.01\times1 = 14.01\ \text{g} \)
• Molar mass of H: \( 1.008\ \text{g/mol} \), moles: \( 9 + 3\times3 = 18 \), mass: \( 1.008\times18 = 18.144\ \text{g} \)
• Molar mass of O: \( 16.00\ \text{g/mol} \), moles: \( 2\times3 = 6 \), mass: \( 16.00\times6 = 96.00\ \text{g} \)
• Total molar mass: \( 14.01 + 18.144 + 288.24 + 96.00 = 416.394\ \text{g/mol} \)

Step3: Calculate percent composition

Percent C: \( \frac{288.24}{416.394} \times 100\% \approx 69.2\% \)

Answer:

\( 69.2\% \)