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Unit Review For Gen Chem II, Exams of Chemistry

Practice questions for gen chem II exam.

Typology: Exams

2020/2021

Uploaded on 09/24/2022

danielle-imani
danielle-imani 🇺🇸

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CHEM 1032 – Fall 2022 Week 5
Unit 1 Review
This worksheet should help you identify how we can use thermodynamics to understand
chemical reactions and builds off the previous work in the unit. It is intended for you to work
through it in order. (Don’t skip ahead.)
Mercury chloride is an incredible toxic compound, where even a small exposure (<1 g) can kill a
human in less than 24 hours. You are tasked with studying the dissolution of mercury chloride
in water.
HgCl2 (s) ßà ___ Hg2+ (aq) + ___ Cl- (aq)
Sº (J/mol K)
f (kJ/mol)
HgCl2 (s)
146.0
-224.3
Hg2+(aq)
84.5
172.4
Cl- (aq)
56.5
-167.2
Use the table above to
Calculate the standard change in entropy for the reaction.
Calculate the standard enthalpy of reaction.
Based on signs of enthalpy and entropy, do you expect the reaction to be spontaneous
or nonspontaneous at standard conditions (25 ºC)? Explain!
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CHEM 1032 – Fall 2022 Week 5

Unit 1 Review

This worksheet should help you identify how we can use thermodynamics to understand chemical reactions and builds off the previous work in the unit. It is intended for you to work through it in order. (Don’t skip ahead.) Mercury chloride is an incredible toxic compound, where even a small exposure (<1 g) can kill a human in less than 24 hours. You are tasked with studying the dissolution of mercury chloride in water. HgCl 2 (s) ßà ___ Hg2+^ (aq) + ___ Cl-^ (aq) Sº (J/mol K) ∆Hºf (kJ/mol) HgCl 2 (s) 146.0 - 224. Hg2+(aq) 84.5 172. Cl-^ (aq) 56.5 - 167. Use the table above to… Calculate the standard change in entropy for the reaction. Calculate the standard enthalpy of reaction. Based on signs of enthalpy and entropy, do you expect the reaction to be spontaneous or nonspontaneous at standard conditions (25 ºC)? Explain!

Calculate the standard free energy change of the reaction. How would you characterize the reaction? Reactants- or products-favored? Why? Is the reaction always spontaneous or always nonspontaneous? Or is it dependent on temperature? If the reaction is dependent on temperature, when will the reaction be spontaneous? If you were to add excess solid HgCl 2 to water at room temp, the concentration of dissolved HgCl 2 would be 0.2752 M. How would you describe the solution? What IMF are present?

If 25.0 mg is the threshold of toxicity for humans, what volume of the 0.2752 M solution would be enough to be lethal?