Question

What is the percent composition by mass of oxygen in ca(no3)2 (gram-formula mass = 164 g/mol)?a.9.8%b.29%c.48%d.59%?

Answer 1

Percent composition by mass of oxygen =
((16.0*6)/(40.1+2*(14.0+16.0*3)))*100%
= 58.5%
therefore, the answer is D

Answer 2

Answer:

A. 9.8%

Explanation:

Percentage Composition = (Mass of element /  Mass of compound) * 100

Mass of oxygen = 16g

Molar mass of Ca(NO3)2

Where;

Ca = 40

N = 14

O =16

Molar mass = 40 + 2[14 + 3(16)] = 164

Substituting into the formular;

Percentage composition = (16 / 164) * 100

Percentage Composition = 0.0975 * 100

Percentage Composition = 9.75% ≈ 9.8 %

Correct option = A