chemistry
posted by Jan .
I'm having a little trouble doing a worksheet.
1.25 moles of KBr contains how many Br atoms?
How do I find the number of atoms for one of them?
Also, I'm not sure how to solve:
Calculate the number of atoms in CO2.
Thanks.

Is that 1.25 or the #1 problem that has 0.25 mols. I'll assume it is 1.25 moles.
1 mole KBr contains 6.02 x 10^23 molecules of KBr so there will be 6.02 x 10^23 x 1.25 = ?? molecules of KBr. You can see that each molecule of KBr contains 1 Br ion. Technically, there aren't ANY Br ATOMS but I think the intent of the problem is to solve for Br ions and call those atoms.
How much CO2? 1 kg, 1 mg, 1 rail car? There are 3 atoms per molecule of CO2; 2 atoms of oxygen and 1 atom of C to make 3 atoms total per molecule CO2. 
Thank you for answering my question. The atom part in the last part was the only thing that confused me. Much appreciated.