# Question 4f2a0

May 2, 2015

So, you to determine how many moles of sodium chloride will be produced when various number of moles of sodium and chlorine take part in the reaction.

Since your question is a little confusing, I'll try and cover as many possibilities as I can and leave you to do the rest.

So, the balanced chemical equation for your reaction is

$\textcolor{red}{2} N {a}_{\left(s\right)} + C {l}_{2 \left(g\right)} \to \textcolor{b l u e}{2} N a C {l}_{\left(s\right)}$

The tool of choice for stoichiometry problems is the mole ratio, which tells you in what proportion the moles of the species involved in the reaction must always be.

So, notice that you have a $\textcolor{red}{2} : 1$ mole ratio between sodium and chlorine gas. This tells you that, regardless of how many moles of chlorine you have, you'll always need twice as many moles of sodium for the reaction to take place.

Likewise, you have a $1 : \textcolor{b l u e}{2}$ mole ratio between chlorine and sodium chloride, which tells you that, regardless of how many moles of chlorine react, you'll always produce twice as many moles of sodium chloride.

So, if, let's say, $\textcolor{red}{2}$ moles of sodium react, you'll need 1 mole of chlorine to participate in the reaction, and produce $\textcolor{b l u e}{2}$ moles of sodium chloride.

If 2 moles of chlorine react, you'll need twice as many moles of sodium, $\textcolor{red}{4}$ moles to be precise, and produce $\textcolor{b l u e}{4}$ moles of sodium chloride.

If $\textcolor{b l u e}{1}$ mole of sodium chloride was produced, $\textcolor{red}{2}$ moles of sodium and 1 mole of chlorine reacted.

So, in a general form, you have

2cancel("moles of Na") * ("1 mole " Cl_2)/(color(red)(2)cancel("moles Na")) = "1 mole " $C {l}_{2}$

2cancel("moles "Cl_2) * (color(red)(2)" moles Na")/(1cancel("mole " Cl_2)) = "4 moles Na"

2cancel("moles of Na") * (color(blue)(2)" moles NaCl")/(color(red)(2)cancel("moles Na")) = "2 moles of NaCl"

1cancel("mole NaCl") * ("1 mole "Cl_2)/(color(blue)(2)cancel("moles NaCl")) = "0.5 moles "Cl_2#

As a conclusion, use the mole ratios that exist between the species that take part in the reaction to determine how many moles of a reactant are needed to produce a certain number of moles of a product, or vice versa.