Simple mole Question (1 Viewer)

[deadbeat]

MC Question


How many moles of oxygen are there in 19.71g CO2 ?




a 0.493 mol
b 0.403 mol
c 2.23 mol
d 867 mol
e 0.896 mol

=>12+16*2 = 44g/mol CO2


=>19.7/44 = 0.448mol CO2

This is where i am not sure.

When they say what mole of "Oygen" do they mean O2 or Just O

If it refers to O2 then its .448mole which isnt one of the options

If it refers to O, then it 0.448x2=.896mol

But really we have 2 molecules of O, not 2 moles of O, so we cant really say .448x2 can we?

 

[ice ken]

e) ftw

 

[BigMik69]

I would say that they are referring to oxygen as just O, because the answer for O2 isnt one of the optional answers.

 

[boris]

MC Question


How many moles of oxygen are there in 19.71g CO2 ?




a 0.493 mol
b 0.403 mol
c 2.23 mol
d 867 mol
e 0.896 mol

=>12+16*2 = 44g/mol CO2


=>19.7/44 = 0.448mol CO2

This is where i am not sure.

When they say what mole of "Oygen" do they mean O2 or Just O

If it refers to O2 then its .448mole which isnt one of the options

If it refers to O, then it 0.448x2=.896mol

But really we have 2 molecules of O, not 2 moles of O, so we cant really say .448x2 can we?

You have one mole of O2 molecule, not two moles of oxygen.

Thats how I would see it anyway



EDIT: I went to Forbes High once.

 

[Mark576]

1 MOL O₂ molecules = 2 MOL O atoms. When you calculate the moles of CO₂, this is equal to the moles of oxygen molecules, and is half the moles of oxygen atoms present. This is correct because one mole is defined as containing Avogadro's number of elementary particles. Thus: 1 MOL O₂ molecules = 2 MOL O atoms, oxygen is diatomic ...therefore the amount of molecules of oxygen present, as a fraction of Avogadro's constant, will give you the moles of the diatomic oxygen molecule, and since a diatomic oxygen molecule contains TWO atoms of oxygen, then the atoms of oxygen present as a fraction of Avogadro's constant will give the moles of oxygen atoms, and then the moles of oxygen atoms will be twice the moles of oxygen molecules. So the correct answer should be (e) <== which is supported in that finding the moles of O₂ doesn't yield any of the m.c.

I'm pretty sure that's correct, though I might have something confused.