Which ∆H Should Be Used in Chemical Equations and Potential Energy Diagrams?

In summary, the conversation discusses the process of calculating ∆H for a system by conducting labs and measuring temperature differences in a calorimeter. The speaker is unsure which ∆H value to use in their chemical equations and potential energy diagram, but it is suggested that they use it on a per mole basis. It is also advised to write out a proper unit formula to determine the appropriate unit to use.
  • #1
rowkem
51
0
So,

I did 5 labs where I burned certain things and found the temp. diff. in the calorimeter. That said, I calculated the ∆H for the entire system, the ∆H per gram of system substance, and the ∆H per mol of system substance.

Im wondering which ∆H I should be putting into my chemical equation for the reaction, as well the ∆H I should be putting into my potential energy diagram? I have a feeling its the ∆H per mole but, I'd like a second opinion. Thanks,
 
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  • #2
Anyone?
 
  • #3
You should do it on a per mole basis.
 
  • #4
Most likely you want to use the mols of the substance in your equations. Write out a proper unit formula and you can see for sure whether you need the mols or grams based on what cancels and what you end up with.
 

FAQ: Which ∆H Should Be Used in Chemical Equations and Potential Energy Diagrams?

What is ∆H and why is it important in a chemical equation?

∆H, or enthalpy change, is the measurement of the heat energy released or absorbed during a chemical reaction. It is important in a chemical equation because it helps us understand the direction and magnitude of the reaction, as well as the amount of energy needed to start or sustain the reaction.

How do I determine the value of ∆H for a specific chemical reaction?

The value of ∆H for a chemical reaction can be determined experimentally by conducting the reaction in a controlled environment and measuring the heat change. Alternatively, it can also be calculated using Hess's Law, which states that the total enthalpy change of a reaction is the sum of the enthalpy changes of its individual steps.

What factors influence the value of ∆H in a chemical equation?

The value of ∆H in a chemical equation is influenced by the nature of the reactants and products, the temperature and pressure of the reaction, and the physical state of the substances involved (solid, liquid, gas). It can also be affected by the presence of a catalyst or changes in concentration or pressure.

How do I know which ∆H value to use in my potential energy diagram?

The ∆H value used in a potential energy diagram should correspond to the overall enthalpy change of the reaction. If the reaction is exothermic (releases heat), the ∆H value should be negative. If the reaction is endothermic (absorbs heat), the ∆H value should be positive. It is important to use the correct ∆H value to accurately represent the energy changes in the reaction.

Can I use the same ∆H value for a reverse reaction in my potential energy diagram?

No, the ∆H value for a reverse reaction will have the opposite sign (positive or negative) from the forward reaction. This is because the energy changes in a reverse reaction are the opposite of those in the forward reaction. Therefore, the correct ∆H value must be used for each reaction direction in the potential energy diagram.

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