Question

Hydrogen gas (7.0 mL) is mixed with chlorine gas(4.0 mL) at a certain pressure and temperature. A
reaction between H2and Cl2 is initiated by UV light.
If pressure and temperature are kept constant, which gases and in which volumes will be found after the reaction is completed?

Answer 1

The reaction is as followed:

H2 + Cl2 ----> 2HCl

You can treat this as a limiting reagent problem, where Cl2 is the limiting reagent.


1 mole of Cl2=2 moles of HCl

or

1mL of Cl2= 2 mL of HCl



4.0mL of Cl2*(2 mL of HCl/Cl2)= 8mL of HCl (g)

Answer 2

For volume H2 unused at the end of the reaction.
4.0 mL Cl2 x (1 mol H2/1 mol Cl2) = 4.0 mL H2 used. Amount H2 left = 7.0-4.0 = 3.0 mL.
So you will have 3.0 mL H2, zero mL Cl2, and 4.0 mL HCl when the reaction is finished.

Answer 3

I didn't fully read this question; I was wondering what Dr.Bob222 did.

He is correct: 4.0mL of of Cl2 will be used meaning that there will be no Cl2 left at the end of the reaction, but 3.0mL of H2 gas will be left after the reaction is complete. However, I'm not sure where the 4.0mL of HCl produced comes from because I think that there will be 8.0mL of the acid will be produced at the end of the reaction.