Chemical Engineering Thermodynamics I

ChE230 Quiz NO.3

Name: _______________________; Student ID: _______________________

1. True or False Questions (10 points)

NO	Statement	True or False
1	Latent heat refers to the heat involved in the phase transformation process.	True
2	Latent heat is only a function of temperature.	False
3	For ideal gas, heat capacity is constant.	True
4	Reaction does not involve energy change.	False
5	Standard state for gas is pure gas in the ideal-gas state at 1 bar.	True
6	Cpig=Cpo	False
7	CO+O2→CO2 is the reaction for CO2 formation reaction.	False
8	CO+O2→CO2 is the reaction for CO combustion reaction.	True
9	C+O2→CO+CO2 is the reaction for CO formation reaction.	False
10	Heat of reaction can be calculated from heat of formation.	True

2. Definitions or Descriptions (10 points)

1. Standard Heat of Reaction:
   The enthalpy change that occurs when a reaction takes place under standard conditions, usually at 1 bar pressure and a specified temperature.
2. Latent Heat:
   The heat absorbed or released by a substance during a phase change at constant temperature and pressure, without a change in temperature.
3. Formation Reaction:
   A chemical reaction in which one mole of a compound is formed from its constituent elements in their standard states, with each element in its most stable form.
4. Standard State:
   The most stable state of a substance at a defined set of conditions, typically at 1 bar pressure and a specified temperature, often 25°C for gases and 0°C for liquids and solids.
5. Standard Heat of Formation:
   The change in enthalpy that occurs when one mole of a compound is formed from its elements in their standard states at a specified temperature, usually 25°C.

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ChE230 Quiz NO.4

1. True or False Questions (10 points)

NO	Statement	True or False
1	Entropy is a state function.	True
2	No process is possible for which the total entropy decreases.	True
3	Every process proceeds in such a direction that the total entropy change associated with it is positive.	False
4	Carnot engine is one type of heat engine.	True
5	For two given heat reservoirs, no engine can have a thermal efficiency higher than that of a Carnot engine.	True
6	For any mechanically reversible adiabatic process, entropy change is zero.	True
7	The maximum work is obtained when the process is completely reversible.	True
8	The maximum work is obtained with Carnot engine.	True
9	Entropy is not conservative, not like energy.	True
10	The rate of entropy generation reflects the irreversibility of the process.	True

2. Definitions or Descriptions (10 points)

1. Heat engine and thermal efficiency:
   A heat engine is a device that converts thermal energy into mechanical work. Thermal efficiency measures the effectiveness of a heat engine in converting thermal energy into useful work. It is defined as the ratio of the useful work output to the heat input.
2. Carnot cycle:
   The Carnot cycle is a theoretical thermodynamic cycle that describes the most efficient heat engine possible. It consists of four reversible processes: isothermal expansion, adiabatic expansion, isothermal compression, and adiabatic compression.
3. Carnot equations:
   The Carnot equations describe the efficiency of a Carnot engine. The efficiency (η) of a Carnot engine operating between two heat reservoirs at temperatures TH (high temperature) and TL (low temperature) is given by:
   η = 1 - (TL / TH)
4. The 2nd law of thermodynamics:
   The second law of thermodynamics states that the total entropy of an isolated system can never decrease over time. In other words, natural processes tend to increase the entropy of the universe.
5. Carnot theorem:
   The Carnot theorem states that no real engine operating between two heat reservoirs can be more efficient than a Carnot engine operating between the same reservoirs. This implies that the Carnot engine is the most efficient engine possible.

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ChE230 Quiz NO.5

1. True or False Questions (10 points)

NO	Statement	True or False
1	When a process is accomplished completely reversibly, the entropy generation is zero.	False
2	When ideal work is negative, the absolute value of ideal work is minimum work obtainable from a given change.	True
3	Thermodynamic efficiency is the same as thermal efficiency.	False
4	Thermodynamic efficiency for Carnot engine equals to 1-Tc/TH.	True
5	Lost work < 0.	False
6	3rd Law of thermodynamics defines absolute value of entropy.	False
7	When P→ 0, residual properties will be zero.	True
8	P and T do not have residual properties.	False
9	G-A = PV	False
10	The order of differentiation in mixed second derivatives is immaterial.	True

2. Definitions or Descriptions (10 points)

1. Thermodynamic efficiency:
   Thermodynamic efficiency refers to the ratio of useful work output to the total energy input in a thermodynamic process. It is a measure of how effectively a system converts energy into useful work.
2. Residual Properties:
   Residual properties are thermodynamic properties of a substance that remain after subtracting the ideal gas contributions. They represent the deviation of real substances from ideal behavior.
3. 3rd Law of Thermodynamics:
   The third law of thermodynamics states that the entropy of a perfect crystal at absolute zero temperature is zero. It provides a fundamental basis for the absolute entropy scale.
4. Ideal Work:
   Ideal work refers to the work done by a system under ideal conditions, where there are no energy losses due to irreversibilities. It represents the maximum work obtainable from a given change.
5. Lost Work:
   Lost work, also known as unavailable work or wasted work, refers to the work that cannot be converted into useful work due to irreversibilities in a thermodynamic process. It is typically associated with entropy generation.

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ChE230 Quiz NO.6

Please answer True (T) or False (F) for each of the following statements (20 points)

NO	Statement	True or False
1	For any system, ∆U=Q+W	False
2	For any process, dW=-PdV	True
3	1st law is not valid for open systems	False
4	At critical point, the freedom variable is zero	False
5	For ideal gas, heat capacity is constant	True
6	Reaction does not involve energy change	False
7	CO+O2→CO2 is the reaction for CO2 formation reaction	False
8	C+O2→CO+CO2 is the reaction for CO formation reaction	False
9	When ideal work is negative, the absolute value of ideal work is minimum work obtainable from a given change	True
10	Thermodynamic efficiency is the same as thermal efficiency	False
11	Thermodynamic efficiency for Carnot engine equals to 1-Tc/TH	True
12	Lost work < 0	False
13	When P→ 0, residual properties will be zero	True
14	U, H, T, P have exact differentials, Q and W do not have exact differentials	True
15	Ideal gas molecules themselves have no volume and no interaction with each other	False
16	For steady state flow system, there is no mass accumulation in the system	True
17	When T>Tc, cubic equations only have one root	False
18	Work from reversible process is maximum	True
19	All cubic equations of state are empirical	True
20	Latent heat refers to the heat involved in the phase transformation process	True
21	Latent heat is only a function of temperature	True
22	Standard state for gas is pure gas in the ideal-gas state at 1 bar	True
23	Cpig=Cpo	False
24	CO+O2→CO2 is the reaction for CO combustion reaction	False
25	Heat of reaction can be calculated from heat of formation	True
26	Entropy is a state function	True
27	No process is possible for which the total entropy decreases	False
28	Every process proceeds in a direction that the total entropy change of the process is positive	True
29	Carnot engine is one type of heat engine	True
30	For two given heat reservoirs no engine can have a thermal efficiency higher than that of a Carnot engine	True
31	For any mechanically reversible adiabatic process, entropy change is zero	True
32	The maximum work is obtained when the process is completely reversible	True
33	The maximum work is obtained with Carnot engine	True
34	Entropy is not conservative, not like energy	True
35	The rate of entropy generation reflects the irreversibility of the process	True
36	When a process is accomplished completely reversibly, the entropy generation is zero	True
37	3rd Law of thermodynamics defines absolute value of entropy	True
38	P and T do not have residual properties	False
39	G-A = PV	False
40	The order of differentiation in mixed second derivatives is immaterial	True

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