Question

A chemist performs the synthesis of sodium chloride from its elements. The chemist begins with 46 grams of sodium. How many moles of chlorine are needed? 2 Na + Cl2 → 2 NaCl

I didn't understand that is it asking about Cl (chlorine) or Cl2 (Chlorine GAS)...

Answer 1

We have `2` `mol` of sodium metal to start; clearly we need the 1 mole of `Cl_2(g)`.

Explanation:

`"Moles of sodium "=(46.0*g)/(22.9*g*mol^-1)=2*mol`.

Given your equation, clearly we need the ONE mole of `Cl_2` gas. What is the mass of this quantity of chlorine?

It is fact that all of the elemental gases EXCEPT for the Noble Gases are diatomic: `N_2, O_2, F_2, Cl_2`. Of course, all the halogens, as the elements, are diatomic, but not all are gaseous.