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Thermochemistry: Entropy Calculations

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Wize High School Grade 12 Chemistry Textbook > Energy Changes

Introduction to Thermochemistry

2 Activities


Using the ΔH0 of fusion for water 6.03 kJ/mol and the ΔS0 of fusion for water 22.1 J K-1 mol-1, calculate the ΔSuniv for ice melting at -10oC, 0oC and 10oC. Remember: the universe transfers heat in a reversible way.


More Introduction to Thermochemistry Questions:
Which of the following is an Intensive Property?
Gibbs Free Energy
The reaction of
H2(g)+CO2(g)↔H2O(g)+CO(g) at 2000K KP=4.40H_{2(g)}+CO_{2(g)}\leftrightarrow H_2O_{(g)}+CO_{(g)}\ at\ 2000K\ K_P=4.40
Calculate ΔG for this reaction
Thermochemistry: Temperature
The oxidation of NO is shown below. Using the provided thermodynamic data answer the following questions
2 NO(g)+O2(g)→2 NO2)g)2\ NO_{(g)}+O_{2(g)}\rightarrow2\ NO_{2)g)}
ΔHo=−57.1kJmol and ΔSo=−73Jmol at 298K\Delta H^o=-57.1\frac{kJ}{mol}\ \text{and}\ \Delta S^o=-73\frac{J}{mol}\ at\ 298K
Thermochemistry: Gibbs Free Energy
The oxidation of NO is shown below. Using the provided thermodynamic data answer the following questions
2 NO(g)+O2(g)→2 NO2)g)2\ NO_{(g)}+O_{2(g)}\rightarrow2\ NO_{2)g)}
ΔHo=−57.1kJmol and ΔSo=−73Jmol at 298K\Delta H^o=-57.1\frac{kJ}{mol}\ \text{and}\ \Delta S^o=-73\frac{J}{mol}\ at\ 298K
Thermochemistry: Equilibrium (Keq)
The Haber Bosch Process is an industrial process for “fixing” nitrogen, shown below.This process produces around 500 million tons of ammonia every year. Calculate Keq
3 H2(g)+N2(g)→ 2 NH3(g)3\ H_{2(g)}+N_{2(g)}\rightarrow\ 2\ \text{NH}_{3(g)}
ΔfGo(NH3)=−16.4 kJ/mol\Delta _fG^o(NH_3)=-16.4\ kJ/mol
Using the following data, calculate the standard entropy change for the reaction:
2Al(s)+3ZnO(s)→Al2O3(s)+3Zn(s)2Al_{(s)}+3ZnO_{(s)}\to Al_2O_{3(s)} +3Zn_{(s)}
Report your answer in J/mol K to four significant figures. Do not include units in the answer field.
A spontaneous process:
Which of the following statements regarding spontaneous changes is false?
A freshly baked pie is placed near an open window to cool. Which of the following statements best describes this situation?
Thermodynamics: Heat and Work
Consider the following balanced chemical equation for the combustion of propane, C3H8:
C3H8(g)+5O2(g)→4H2O(ℓ)+3CO2(g)q<0C_3H_8 (g) + 5 O_2 (g) → 4 H_2O (ℓ) + 3 CO_2 (g) \qquad q < 0
Use this information to answer the next two questions. Choose one if the options inside the brackets
If a reaction is nonspontaneous at 298 K with a negative ΔHo, then the reaction is:
Select all that apply
The oxidation of NO is shown below. Using the provided thermodynamic data answer the following questions
2 NO(g)+O2(g)→2 NO2)g)2\ NO_{(g)}+O_{2(g)}\rightarrow2\ NO_{2)g)}
ΔHo=−57.1kJmol and ΔSo=−73Jmol at 298K\Delta H^o=-57.1\frac{kJ}{mol}\ \text{and}\ \Delta S^o=-73\frac{J}{mol}\ at\ 298K
The oxidation of NO is shown below. Using the provided thermodynamic data answer the following questions
2 NO(g)+O2(g)→2 NO2)g)2\ NO_{(g)}+O_{2(g)}\rightarrow2\ NO_{2)g)}
ΔHo=−57.1kJmol and ΔSo=−73Jmol at 298K\Delta H^o=-57.1\frac{kJ}{mol}\ \text{and}\ \Delta S^o=-73\frac{J}{mol}\ at\ 298K
Find ΔG0 for the following reaction.
CH4(g)+2 O2(g)→2 H2O(g)+CO2(g)\text{CH}_{4(g)}+2\ O_{2(g)}\rightarrow 2\ H_2O_{(g)}+\text{CO}_{2(g)}
Consider the following vaporization:
CH3CH2OH(l)→CH3CH2OH(g)CH_3CH_2OH_{(l)}\to CH_3CH_2OH_{(g)}
If ∆Hvap = 39.3 kJ/mol and the boiling point of ethanol is 78.3°C, what is ΔS for the vaporization of 1.73 mols of ethanol at its boiling point?
Predict the sign of the ΔH, ΔS,(+ or -) and identify when the following reactions are spontaneous at low temperature, high temperature, or all temperatures (low, high, all). Use commas to write your answers ie. +,+,low
For freezing of a popsicle: ΔH is ___________, ΔS is ___________. Reaction is spontaneous at ____________________ temperatures
For evaporation of liquid water: ΔH is ___________, ΔS is ___________. Reaction is spontaneous at ____________________ temperatures
Arrange the following compounds in order of increasing entropy, assuming 1 mol of each compound:
Ar(g)Fe(s)CH3CH2CH3(g)HOCH2CH2CH2OH(l)Ar(g) \hspace{15pt}Fe(s)\hspace{15pt} CH_3CH_2CH_{3(g)} \hspace{15pt} HOCH_2CH_2CH_2OH_{(l)}
Ar(g)Ar(g)
Calculate ΔSsys ΔSsurr and ΔSUniv for the combustion of hydrogen shown below (unbalanced). Is the process spontaneous?
H2(g)+O2(g)→H2O(g)H_{2(g)}+O_{2(g)}\rightarrow H_2O_{(g)}
ΔHf0(H2O(g)) = -285.83 kJ/mol
Thermodynamics: Entropy Calculations
Using the following data, calculate the standard entropy of the reaction shown below. Enter your answer in units of J / (mol*K)
2 Al(s)+3 ZnO(s)→Al2O3(s)+3Zn(s)2\ Al_{(s)}+3\ ZnO_{(s)}\rightarrow Al_2O_{3(s)}+3Zn_{(s)}
So(Al(s))=28.3 J mol−1K−1S^o(Al_{(s)})=28.3\ J\ mol^{-1}K^{-1}