Step 1 - "reading" the chemical equation
The given chemical equation is:
[tex]\text{NaI}_{(s)}+Cu_{(s)}\to\text{CuI}_{2(s)}+Na_{(s)}[/tex]The proportion in moles for any chemical equation is given by the "bigger" numbers, those that come before the formula of the substances. We can use them to "read" what the equation is telling us:
1 mole of NaI react with 1 mole of Cu thus producing 1 mole of CuI2 and 1 mole of Na
Since the exercise has specifically asked us about the proportion between sodium iodide (NaI) and copper (Cu), we can simplify the statement to:
1 mole of NaI react with 1 mole of Cu
Therefore, we always need the same quantitie, in moles, of NaI and Cu for this reaction to occur completely.
Step 2 - Discovering how many moles of sodium iodide are required
Since the proportion between NaI and Cu, as we saw, is 1:1 in moles, whenever we use, let's say, x moles of Cu, we will need x moles of sodium iodide as well.
Therefore, the amount needed of sodium iodide would be exactly 3.2 moles.
