posted by will on .
sodium reacts completely with 0.142kg of chlorine, forming 234g of sodium chloride. What mass of sodium reacted?
I know that for chemical changes the amounts should end up being equal, but I don't know how to set up the problem.
It is the number of atoms, or moles, of Na which is equal to the number of atoms, or moles, of Cl in NaCl
Na = 23 grams/mol
Cl = 35.5 grams/mol
NaCl = 58.5 grams/mol
so if we ended up with 234 grams ofNaCl, that was 4 mols of NaCl
That requires 4*23 = 92 grams of Na
That requires 4*35.5 = 142 grams of Cl, sure enough
92 is the correct answer.