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?

1 Answer
Oct 26, 2016

Answer:

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.