Question

question 7 (1 point)
use the data from the previous question calculate the % oxygen in ca3(po3)2 to 4 significant figures. choose the closest answer.
% o = -----------100 = 1% oxygen
a. 1.112 x 1010 b. 3.983 x 103 c. 2.394 x 104 d. 0.03595 e. 2.898 f. 2.162 x 1022 g. 0.3451 h. 1.675 x 1025 i. 1.853 x 109 j. 34.51 k. 1.436 x 105 l. 2.782 x 103 m. 3.996 x 107 n. 5.969 x 10-26 o. 5.969 x 1026 p. 3.595 x 10-2 q. 2.782 x 10-3

Explanation:

Step1: Calculate molar mass of \(Ca_3(PO_3)_2\)

• Molar mass of \(Ca = 40.08\ g/mol\), \(P = 30.97\ g/mol\), \(O = 16.00\ g/mol\)
• For \(Ca_3(PO_3)_2\):
• \(n(Ca)=3\), \(n(P) = 2\), \(n(O)=6\)
• \(M(Ca_3(PO_3)_2)=3\times40.08+2\times30.97 + 6\times16.00\)
• \(M(Ca_3(PO_3)_2)=120.24+61.94+96.00=278.18\ g/mol\)

Step2: Calculate mass of oxygen in \(Ca_3(PO_3)_2\)

• Mass of \(O\) in \(Ca_3(PO_3)_2\): \(m(O)=6\times16.00 = 96.00\ g/mol\)

Step3: Calculate \(\%\) of oxygen

• \(\%\ O=\frac{m(O)}{M(Ca_3(PO_3)_2)}\times100=\frac{96.00}{278.18}\times100\)
• \(\%\ O=\frac{9600}{278.18}\approx34.51\)

Answer:

J. 34.51