Question

An sodium metal salt is prepared from `3.0*g` metal and `2.0*g` of iodine. What is the MAXIMUM possible mass of `NaI` that can be prepared?

Answer 1

Well, first you need a stoichiometric equation......

Explanation:

`Na + 1/2I_2 rarr NaI`

`"Moles of metal"` `=` `(3.0*g)/(22.99*g*mol^-1)` `=` `0.131*mol`.

`"Moles of halogen"` `=` `(2.0*g)/(2xx126.9*g*mol^-1)` `=` `1.24xx10^-4*mol`.

Now clearly, the metal is present in vast stoichiometric excess. At most, we can form `2.48xx10^-4*mol` of salt. I leave it to you to determine the mass of salt possible.

Note that the halogens, as elements, are all binuclear, `X_2`, and this is knowledge that the examiner expects. All elemental gases, save for the Noble Gases, and (maybe) mercury, are binuclear.