Week 5 and 6 Assignment Question 9 - Deciding Which Equation to Use for Systems or Surroundings
Posted: Sat Feb 11, 2023 11:06 am
Here is the homework problem.
Consider the following reaction at 298 K.
4Al(s)+3O2(g)⟶2Al2O3(s)ΔH∘=−3351.4 kJ
Calculate the following quantities. Refer to the standard entropy values as needed.
I correctly calculated the answer using standard molar entropies to find ΔSsys, and I correctly calculated ΔSsurr using ΔSsurr = −ΔHsys / T.
However, I do not understand why I need to use different equations for ΔSsys and ΔSsurr. Why is ΔSsys not calculated using ΔHsys / T? Additionally, when is it proper to use ΔHsys/T, and what is the underlying concept?
Thanks!
Consider the following reaction at 298 K.
4Al(s)+3O2(g)⟶2Al2O3(s)ΔH∘=−3351.4 kJ
Calculate the following quantities. Refer to the standard entropy values as needed.
I correctly calculated the answer using standard molar entropies to find ΔSsys, and I correctly calculated ΔSsurr using ΔSsurr = −ΔHsys / T.
However, I do not understand why I need to use different equations for ΔSsys and ΔSsurr. Why is ΔSsys not calculated using ΔHsys / T? Additionally, when is it proper to use ΔHsys/T, and what is the underlying concept?
Thanks!