Hello,
Can someone help me with this question?
Consider these reactions, where M represents a generic metal.
2M(s)+6HCl(aq)⟶2MCl3(aq)+3H2(g) deltaH1=−902.0 kJ
HCl(g)⟶HCl(aq) deltaH2=−74.8 kJ
H2(g)+Cl2(g)⟶2HCl(g) deltaH3=−1845.0 kJ
MCl3(s)⟶MCl3(aq) deltaH4=−436.0 kJ
Use the given information to determine the enthalpy of the reaction
2M(s)+3Cl2(g)⟶2MCl3(s)
Thank you!
Achieve HW #5
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Re: Achieve HW #5
The first step is to set up the combination of reactions that give you the final reaction. If you have to reverse the reaction, then delta H changes signs (like negative to positive for example) and when you have to multiply the reaction to get certain coefficients, you also have to multiply the delta H value. Then you combine all the delta H's of the reactions you manipulated and combined to get a final value for delta H. Hope this helps!
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Re: Achieve HW #5
Hi! For this problem you will utilize Hess's Law. You need to figure out how to manipulate the example reactions so that they cancel out to get the given reaction. Remember, when you manipulate a reaction, you also need to change the change in enthalpy. When you multiply the reaction by a coefficient, do the same to deltaH. When you reverse the reaction, you flip the sign of deltaH. In this specific example you will need to use all 4 reactions to get the resulting reaction, but you will not need to manipulate all the reactions. I hope this helps!
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Re: Achieve HW #5
Hi! This one can be a little tricky if you don't pay attention to the state of the molecules. First, you need to know that all the reactions will be manipulated since you are trying to achieve 2M(s)+3Cl2(g)⟶2MCl3(s). For the first reaction, you can leave it alone since you want 2M(s). For the second reaction, you will need to multiply it by 6 in order to get rid of the HCl(aq). For the third reaction, you will need to multiply it by 3 in order to get rid of H(g) and HCl(g). For the final reaction, you will need to inverse and multiply it by 2 to get rid of the MCl3(aq).
While you're following these steps, write everything out to ensure that you understand that process as to how you reached the final reaction. Remember that in order to find the total enthalpy, you need to multiply the individual enthalpies that you also multiplied by in the reaction, and whatever you inversed, the sign of the enthalpy will be the opposite. Hope this helps!
While you're following these steps, write everything out to ensure that you understand that process as to how you reached the final reaction. Remember that in order to find the total enthalpy, you need to multiply the individual enthalpies that you also multiplied by in the reaction, and whatever you inversed, the sign of the enthalpy will be the opposite. Hope this helps!
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Re: Achieve HW #5
Hi! So for this problem you need to manipulate each equation given until it is the same equation as the one it asks the enthalpy for. With each manipulation comes the changing of H. When you need to multiply an equation, you also need to multiply its H value. If you have to flip an equation, all you have to do is change the sign of H. Then, you add all of the new H's together and this should give you your answer.
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