Write down the formula of a compound in which the mass fractions of calcium and oxygen are 71.43% and 28.57%, respectively

univerkov | November 17, 2020 | education

Given: w (Ca) = 71.42%; w (O2) = 28.57%
Find: formula
Decision:
1) m (Ca) = w * 100 = 0.7142 * 100 = 71.42g
m (O2) = w * 0.2857 * 100 = 28.57g
2) n (Ca) = m / M = 71.42g / 40g / mol = 1.78mol
n (O2) = m / M = 28.57g / 32g / mol = 0.89 mol
3) n (Ca): n (O2) = 1.78: 0.89 = 2: 1
Answer: Ca2O

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