Which of the following has the largest number of oxygen atoms?

Question

$a)$ $3.65 xx 10^20$ molecules of $"SO"_2$
$b)$ $3.65 xx 10^20$ molecules of $"SO"_3$
$c)$ $"0.0553 g SO"_3$
$d)$ $5.06 xx 10^(-3) "mols SO"_3$

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Answer 1 · 2017-07-06T05:02:40

The biggest amount of oxygen is in $"5,06" × 10^"-3"$ mol.

Since a mol is $6,02 xx 10^23$ molecules, you have $(3,65 xx 10^20)/ (6,02 xx 10^23)= 6,06 xx 10 ^(-4)$ mol each of $SO_2$ and $SO_3$ .

Obviously, there are more oxygen atoms in $SO_3$ .

Furthermore, since the MM of $SO_3$ is 80.1 g/mol you have $(0,0553 g)/(80.1 g/(mol)) = 6,90 xx 10^(-4) mol SO_3$ .

Then, the bigger amount of oxygen is in the 0,0553 g of $SO_3$ where there is a bigger number of moles.

And $"5,06" × 10^"-3"$ mol of $SO_3$ contains even more moles than 0,0553 g of $SO_3$ .