[Larianne]

Question:
How many carbon atoms are present in 2.0g of the following:

a) CO₂

Okay so I worked out the moles of 2.0 g CO<sub>2

n= 2g
    ----                       =   0.046 mol
    44gmol^-1

I then worked out the mole ratio between Carbon and Oxygen which is 1:2
So the I got the amount of moles of Carbon in CO2 0.5 x 0.046 mol = 0.023 mol

I then got number of particles of Carbon = 0.023mol x 6.022x 10²³ and the answer I got was 1.385x10²²

The answer in the book is 2.73x10²².

Where am I going wrong?</sub>

[Astrokel]

I then worked out the mole ratio between Carbon and Oxygen which is 1:2

No, in 1 mole of CO

2

, how many moles of carbon do you have?

[Larianne]

1 Carbon -

so it's 0.046545 mol x 6.022 x 10²³

which is 2.73 x10 ²²

Which is the right answer!!!!!

You know I did it this way first but rounded the moles to 0.046 and I was getting 2.77!

Thanks for that.   

[Larianne]

And just to clarify, as I have 5 other similar questions:

If the substance is C₂H₄ I worked out the moles for the whole substance and then multiply the answer by two as there is 2 Carbon atoms present??

[Astrokel]

sorry about my last post i accidentally pressed on the quote button, i meant CO₂

And just to clarify, as I have 5 other similar questions:

If the substance is C2H4 I worked out the moles for the whole substance and then multiply the answer by two as there is 2 Carbon atoms present??

Yes every 1 mole of C2H4, there are 2 moles of carbon

[kosata78zw]

Question:
How many carbon atoms are present in 2.0g of the following:

a) CO₂

Okay so I worked out the moles of 2.0 g CO<sub>2

n= 2g
    ----                       =   0.046 mol
    44gmol^-1

I then worked out the mole ratio between Carbon and Oxygen which is 1:2
So the I got the amount of moles of Carbon in CO2 0.5 x 0.046 mol = 0.023 mol

I then got number of particles of Carbon = 0.023mol x 6.022x 10²³ and the answer I got was 1.385x10²²

The answer in the book is 2.73x10²².

Where am I going wrong?</sub>

yes dear the book is right .. because when u r using Avogadro's No. u r finding the no. of particles (molecules of carbon dioxide) & the no. of carbon atoms = the no. of carbon dioxide molecules (every CO2 molecule contains 1 C atom) so .. no need for the ratio