#H_2(g) + Cl_2(g) -> 2HCl(g)+#. If 2 mol of hydrogen gas are mixed with 4 mol of chlorine gas, how many moles of hydrogen chloride will be produced?

1 Answer
Mar 30, 2017

Answer:

4 moles of HCl are produced

Explanation:

The ratio at which the compounds react with each other are displayed in a chemical reaction as the numbers in front of the compounds. For example in this reaction:

1 #H_2# molecule reacts with 1 #Cl_2# molecule
Forming
2 #HCl# molecules.

In chemistry moles are used as a handy number of a certain amount of stuff. You can compare this to a dozen eggs, which is always 12. In the same way 1 mol is the number #6.022*10^(23)#. This number tells us how many particles there are. So in 1 mol there are #6.022*10^(23)# particles. This number is also referred to as the constant of Avogadro.

In the question the amount of moles for #H_2# and for #Cl_2# are given. We have to calculate how much #HCl# is produced with both these values. Therefore 2 calculations needs to be done.

Because moles just tells us something about the amount of particles we can use the ratio of the reaction to calculate how many #HCl# will be produced.

We start of with the 2 moles of hydrogen gas. We know the following now:
1 mole of #H_2# gives 2 moles of #HCl#
Therefore
2 moles of #H_2# gives 4 moles of #HCl#

Now this same calculation can be done for the #Cl_2#:
1 mole of #Cl_2# reacts to 2 moles of #HCl#, therefore
4 moles of #Cl_2# reacts to 8 moles of #HCl#.

Now we see we have 2 different amount of moles for #HCl# and the question now is which one should we use?
We must now look at which one of above reactions can occur? So for the 2 moles of #H_2#, we can calculate with the ratio that:
2 moles of #H_2# reacts with 2 moles of #Cl_2#.
We do have 2 moles of #Cl_2# available!

Let's see the other one
4 moles of #Cl_2# reacts with 4 moles of #H_2#
But we do not have 4 moles of #H_2#!!

Therefore we can only make 4 moles of #HCl# instead of 8 moles.

This situation can be stated as following: The #Cl_2# is abundant.