Answer:
A. Mass percent composition of oxygen = 58.5%
B. Mass percentage composition of oxygen = 42.1%
C. Mass percentage composition of oxygen = 72.7 %
Step-by-step explanation:
Percentage mass composition of an element in a compound is given by the formula below:
Percentage mass composition = mass of element/ molar mass of compound × 100%
Percentage mass of oxygen in the given compounds are then calculated.
a. Calcium nitrate, Ca(NO₃)₂: molar mass of compound is obtained first.
Molar mass of Ca(NO₃)₂ = 40 + 14 × 2 + 16 × 2 × 3 = 164 g
Mass of oxygen = 16 × 6 = 96 g
Mass percent composition of oxygen = 96/164 × 100% = 58.5%
b. Iron (ii) sulfate, FeSO₄: molar mass of compound is obtained first.
Molar mass of FeSO₄ = 56 + 32 + 16 × 4 = 152 g
Mass of oxygen = 16 × 4 = 64 g
Mass percentage composition of oxygen = 64/152 × 100% = 42.1%
c. Carbon dioxide, CO₂: molar mass of compound is obtained first.
Molar mass of CO₂ = 12 + 16 × 2 = 44 g
Mass of oxygen = 16 × 2 = 32 g
Mass percentage composition of oxygen = 32/44 × 100% = 72.7 %