How do you know how many atoms are in CO2?

Answer 1

You first have to find how many moles of CO2 you have

so you find its molar mass, (Carbon=12 Oxygen = 16(2))

then you add 12+32 to get the molar mass which is 44

you should also be given a mass, of how much CO2 there is..

or else you cannot calculate the moles.

moles are mass/molar mass

once you get the moles

just multiply the number of moles by

Avogadros constant (6.02x1023)

Say if the mass was 4.56 g of C02 that you had

then you just do 4.56/44 = 0.103636363 mol

now multiply that by avogadro's constant

and you have the number of atoms/particles/formula units

Answer 2

To determine the number of atoms in CO2, you look at the chemical formula. In this case, CO2 means one carbon atom (C) and two oxygen atoms (O) making a total of three atoms in a molecule of carbon dioxide.