Using Hess's Law in Problem 5 (Achieve HW)

[Jess Cooper 1C]

Hello!
I am trying to do problem 5, and had a question about using Hess's Law. If I'm given a set of reactions, do I need to use ALL of them? Or can i just use the ones that make sense for the problem? I feel like I'm doing it correctly but it keeps telling me it's wrong. Here's what I've done so far (I only used the equations in blue)

[img]Screen%20Shot%202023-02-06%20at%207.09.41%20AM.png[/img]

[Tricia Tran 1G]

In general, you do not need to use all the equations given and only the ones that make sense. However, for this Achieve question, all the equations are necessary. Be careful with states of matter. The 2MCl3 from the first equation is in aqueous state but the one in the final equation you're trying to get to should be a solid. That's why you need to use equation 4 to switch the states. The same thing applies to HCl in the 3rd equation where you need to switch it to aqueous (using the 2nd equation) before you can cancel it from the first equation. Hope this helps!

[Gauri Gusain 3H]

You only need to use the equations that you need in order to get the overall the final equation. However make sure that you are paying attention to the state symbols as they are the ones that usually trick students into thinking that they removed that molecule when they really did not!

[505736451]

When using Hess's Law, you only need to use the equations relevant to the given equation. However it is important to remember that sometimes an equation with no similar reactants or products with the given equation needs to be used in order to cancel extra reactants or products used in other equations.