Posted by Summer on .
Each molecule of NO2, nitrogen dioxide, consists of 1 atom of N and 2 atoms of O. If you have 0.155 g. of NO2, how many molecules of NO2 do you have ?
If you could, please include steps as to how to do the problem.
Thank you

Chemistry 
DrBob222,
How many moles NO2 do you have? That is grams/molar mass = 0.155/46.0 = about 0.003 (but you need to do it more accurately).
1 mole NO2 contains how many molecules NO2. 1 mole of NO2 contains 6.022E23 molecules; so how many molecules NO2 do you have? That is 0.003 moles NO2 x (6.022EE23 molecules/mole) = about 2E21. 
Chemistry 
Summer,
Thank you :)
2030000000000000000000 was the correct answer
Part 2:
How many atoms of N do you have ? 
Chemistry 
DrBob222,
Many profs will count your answer as incorrect. By placing that many zeros after the number you indicate there are 21 significant figures and that isn't correct. There are only 3 (dictated by the 0.155 gram in the initial sample) so the correct way to show this is 2.03E21.
For the correct number of N atoms, there is 1 N per NO2 molecule; therefore, the number of atoms N is the same as the number of molecules of NO2. There will be twice that number for the number of O atoms. 
Chemistry 
Summer,
Our work is online, and I tried to enter it as 2.03E21 and it would not accept it.
It only accepts the answer if everything is correct.
Thank you :) 
Chemistry 
DrBob222,
OK. I suppose you play the game the way it works; however, 2.03E21 is the correct way of writing that number.

Chemistry 
Summer,
Than you can be the one to tell my prof that, sir :)