Question

multiple choice 1 point kaolinite, a clay mineral with the formula al₄si₄o₁₀(oh)₈, is used as a filler in slick - paper for magazines and as a raw material for ceramics. calculate the mass percent of oxygen in kaolinite. options: 1.792 mass%, 30.81 mass%, 55.81 mass%, 24.89 mass%, 34.12 mass%

Explanation:

Step1: Calculate molar mass of kaolinite

The formula of kaolinite is $\ce{Al_{4}Si_{4}O_{10}(OH)_{8}}$.
Molar mass of $\ce{Al}$: $26.98\ \text{g/mol}$, $\ce{Si}$: $28.09\ \text{g/mol}$, $\ce{O}$: $16.00\ \text{g/mol}$, $\ce{H}$: $1.008\ \text{g/mol}$.

Molar mass of $\ce{Al_{4}Si_{4}O_{10}(OH)_{8}}$:
$4\times26.98 + 4\times28.09 + 18\times16.00 + 8\times1.008$
$= 107.92 + 112.36 + 288.00 + 8.064$
$= 516.344\ \text{g/mol}$

Step2: Calculate mass of O in 1 mol

In $\ce{Al_{4}Si_{4}O_{10}(OH)_{8}}$, number of O atoms: $10 + 8 = 18$.
Mass of O: $18\times16.00 = 288.00\ \text{g/mol}$.

Step3: Calculate mass percent of O

Mass percent = $\frac{\text{Mass of O}}{\text{Molar mass of kaolinite}} \times 100\%$
$= \frac{288.00}{516.344} \times 100\% \approx 55.78\% \approx 55.81\%$

Answer:

55.81 mass%