17.3 g of oxygen contains a. 1.04 × 1025 oxygen molecules b. 1.08 mol of oxygen molecules c. 35 amu d. none of the above e. 6.51 × 1023 oxygen atoms

Answer 1

Hello, Anjela,

We have 17.3 grams of oxygen. But the possible answers are all in units that don't quickly allow us to pick the correct one, so let's convert grams O₂ to moles O₂ by dividing by oxygen's molar mass of 32 grams/mole, and go from there:

(17.3 g O₂)/(32 g/mole O₂) = 0.541 moles O₂

This means that choice b) isn't correct.

We know that 1 mole = 6.02x10²³ molecules, so calculate the number of O₂ molecules

(0.541 moles)*(6.02x10²³ molecules/mole) = 3.255x10²³ molecules O₂

This means choice a) is also incorrect.

Choice c) of 35 amu doesn't address the question, and comes close, but doesn't even equal the correct molar mass of O₂ (2 x 16 = 32 amu).

Hmmm . . that leaves just answer choices d and e, and we can't choose d until we know e is incorrect. It states we have 6.51x10²³ oxygen atoms. Each moleof O₂ has 2 atoms, so (2)*(3.25x10²³ molecules O₂) = 6.51x10²³ atoms of oxygen, O. That's the answer choice, so I'd go with e.

Bob