Question

calculate the percent composition by mass of calcium in the fictional compound shown below. include the units, but do not write the chemical formula. round the answer to 3 significant figures. ca₅co₂o₈ calcium =

Explanation:

Step1: Calculate molar mass of Ca

Calcium (Ca) has atomic mass ~40.08 g/mol. There are 5 Ca atoms. So mass of Ca: $5 \times 40.08 = 200.4$ g/mol.

Step2: Calculate molar mass of Co

Cobalt (Co) has atomic mass ~58.93 g/mol. There are 2 Co atoms. Mass of Co: $2 \times 58.93 = 117.86$ g/mol.

Step3: Calculate molar mass of O

Oxygen (O) has atomic mass ~16.00 g/mol. There are 8 O atoms. Mass of O: $8 \times 16.00 = 128.0$ g/mol.

Step4: Calculate total molar mass

Total molar mass = 200.4 + 117.86 + 128.0 = 446.26 g/mol.

Step5: Calculate percent composition of Ca

Percent composition = $\frac{\text{Mass of Ca}}{\text{Total molar mass}} \times 100\% = \frac{200.4}{446.26} \times 100\% \approx 44.9\%$ (rounded to 3 significant figures).

Answer:

44.9%