H_2(g) + Cl_2(g) -> 2HCl(g)+H2(g)+Cl2(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

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_2H2 molecule reacts with 1 Cl_2Cl2 molecule
Forming
2 HClHCl 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)6.0221023. This number tells us how many particles there are. So in 1 mol there are 6.022*10^(23)6.0221023 particles. This number is also referred to as the constant of Avogadro.

In the question the amount of moles for H_2H2 and for Cl_2Cl2 are given. We have to calculate how much HClHCl 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 HClHCl will be produced.

We start of with the 2 moles of hydrogen gas. We know the following now:
1 mole of H_2H2 gives 2 moles of HClHCl
Therefore
2 moles of H_2H2 gives 4 moles of HClHCl

Now this same calculation can be done for the Cl_2Cl2:
1 mole of Cl_2Cl2 reacts to 2 moles of HClHCl, therefore
4 moles of Cl_2Cl2 reacts to 8 moles of HClHCl.

Now we see we have 2 different amount of moles for HClHCl 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_2H2, we can calculate with the ratio that:
2 moles of H_2H2 reacts with 2 moles of Cl_2Cl2.
We do have 2 moles of Cl_2Cl2 available!

Let's see the other one
4 moles of Cl_2Cl2 reacts with 4 moles of H_2H2
But we do not have 4 moles of H_2H2!!

Therefore we can only make 4 moles of HClHCl instead of 8 moles.

This situation can be stated as following: The Cl_2Cl2 is abundant.