Problem: Consider these reactions, where M represents a generic metal.1.  2M (s) + 6HCl (aq)  →  2MCl3 (aq) + 3H2 (g)                 ΔH1 = -579.0 kJ2. HCl (g) → HCl (aq)                                                         ΔH2 = -74.8 kJ3. H2 (g) + Cl2 (g) → 2HCl (g)                                            ΔH3 = -1845.0 kJ4. MCl3 (s) → MCl3 (aq)                                                     ΔH4 = -141.0 kJUse the following information above to determine the enthalpy (kJ) of the following reaction.2 M(s) +  3Cl2 (g) → 2 MCl3 (s)

FREE Expert Solution
FREE Expert Solution

We’re being asked to determine the enthalpy change (ΔHrxn) for the chemical reaction:


2 M(s) + 3 Cl2(g)  2 MCl3(s)


We can use Hess’s Law to determine the enthalpy change of the overall reaction from the given reactions:


1. 2 M(s) + 6 HCl(aq)  2 MCl3(aq) + 3 H2(g)                 ΔH1 = –579.0 kJ

2. HCl(g)  HCl(aq)                                                         ΔH2 = –74.8 kJ

3. H2(g) + Cl2(g)  2 HCl(g)                                             ΔH3 = –1845.0 kJ

4. MCl3(s)  MCl3(aq)                                                      ΔH4 = –141.0 kJ


We now need to find a combination of reactions that when added up, gives us the overall reaction.


View Complete Written Solution
Problem Details

Consider these reactions, where M represents a generic metal.

1.  2M (s) + 6HCl (aq)  →  2MCl3 (aq) + 3H2 (g)                 ΔH1 = -579.0 kJ
2. HCl (g) → HCl (aq)                                                         ΔH2 = -74.8 kJ
3. H2 (g) + Cl2 (g) → 2HCl (g)                                            ΔH3 = -1845.0 kJ
4. MCl3 (s) → MCl3 (aq)                                                     ΔH4 = -141.0 kJ

Use the following information above to determine the enthalpy (kJ) of the following reaction.

2 M(s) +  3Cl2 (g) → 2 MCl(s)


Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Hess's Law concept. You can view video lessons to learn Hess's Law. Or if you need more Hess's Law practice, you can also practice Hess's Law practice problems.

What is the difficulty of this problem?

Our tutors rated the difficulty ofConsider these reactions, where M represents a generic metal...as medium difficulty.

How long does this problem take to solve?

Our expert Chemistry tutor, Dasha took 10 minutes and 42 seconds to solve this problem. You can follow their steps in the video explanation above.