18 Questions
Define an extensive property of a system and provide an example.
An extensive property depends on the quantity of matter in the system. Example: mass.
What is an intensive property of a system? Give an example.
An intensive property does not depend on the quantity of matter in the system. Example: temperature.
What does it mean for a thermodynamic system to be in a state?
A thermodynamic system is in a state when all its thermodynamic properties are fixed.
How can the state of a system be changed?
The state of a system can be changed by altering the values of its thermodynamic properties.
According to the ideal gas equation, what does PV=nRT represent?
PV=nRT represents the ideal gas equation for a gas with 'n' moles.
What are the three state variables that determine the state of a system?
Pressure, volume, and temperature are the three state variables that determine the state of a system.
What is the first law of thermodynamics equation?
q = △E + P△V
Define the relationship between enthalpy and internal energy at constant pressure.
△H = △E + △nRT
What does it indicate if △n = 0 in a chemical reaction?
△H = △E
In an exothermic reaction, how does △H compare to △E?
△H < △E
What is the ideal gas equation for reactants and products involving gases at constant pressure and temperature?
P(V2 – V1) = (n2 – n1) RT
Explain the energy profile diagram in the context of chemical reactions.
The diagram shows the energy levels of reactants and products, with energy being absorbed or released during bond formation or breaking.
What does Lavoisier and Laplace law state?
The enthalpy change of a chemical reaction is equal but opposite in sign for the reverse reaction.
Mathematically, how is the enthalpy change of a backward reaction related to the forward reaction?
ΔH_forward reaction = -(ΔH_backward reaction)
Explain Hess's Law of Constant Heat Summation.
The total change in enthalpy in a chemical reaction is constant, regardless of the number of steps involved.
How can the enthalpy change of a reaction be calculated using Hess's Law?
ΔH = ΔH1 + ΔH2 + ΔH3
What does Hess's Law imply about the change in enthalpy of a chemical reaction?
It depends on the initial and final state of the reaction, not the number of steps involved.
Explain the scenario where Q2 > Q1 according to Hess's Law.
If Q2 > Q1, transforming a reactant to product and then back would result in a gain of heat energy.
Test your knowledge on the first law of thermodynamics and the relation between enthalpy and internal energy. Understand how to calculate heat content and analyze reactions involving gases at constant pressure and temperature.
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