Chapter 5 Quiz Flashcards
System
Part of the universe being studied
Surroundings
Rest of the universe that interacts with the system
First Law of Thermodynamics
-Law of conservation of energy
-Energy can be neither created or destroyed in an isolated system
Enthalpy
sum of the total energy of the system and the work done
exothermic reaction
When ΔH is negative, heat is released by the system (ex: Hand warmers)
endothermic reaction
When ΔH is positive, heat is absorbed by the system (ex: freezer packs)
Heat Capacity
the amount of energy required to raise the temperature of a substance by 1 K (1 *C).
Specific heat capacity
( specific heat)- the amount of energy required to raise the temperature of 1 g of a substance by 1 K (or 1 *C).
State Function
-Function to define the system for only its current state, not the path on how it arrived to that state.
- It depends only on the present state of the system, not on the path by which the system arrived at that state.
Example= (triangle) H (Enthalpy) is a state function, the total enthalpy change depends only on the initial state (reactants) and the final state (products) of the reaction.
Hess’s Law
Hess’s law: If a reaction is carried out in a series of steps, (triangle) H for the overall reaction will be equal to the sum of the enthalpy changes for the individual steps.
In thermodynamics, work is defined as
c) Force applied over a distance W=P/\V
What is the SI unit of energy?
b) Joule
Which of the following is true for an exothermic reaction?
c) ΔH is negative
What is the term for the amount of heat required to raise the temperature of 1 gram of
a substance by 1°C?
b) Specific heat capacity
A system absorbs 100 J of heat and performs 40 J of work. What is its change in
internal energy?
a) 60 J
- If a system releases 200 J of heat and does 50 J of work on the surroundings, what is
the change in internal energy (ΔE)?
a) -250 J
If a system absorbs 500 J of heat and performs 200 J of work, what is the change in internal energy (ΔE)?
b) +300 J
The enthalpy change (ΔH) for an
c) Negative
In an open system, which of the following can be exchanged with the surroundings?
c) Both matter and energy
A closed system allows the exchange of
a) Only heat and work
Which of the following is an example of an isolated system?
b) A sealed thermos bottle
Which of the following best describes an open system?
b) A boiling pot of water without a lid
In a closed system, which of the following is true?
b) The system cannot exchange matter with the surroundings.
In an endothermic reaction:
b) Heat is absorbed by the system
- Which of the following has the highest specific heat capacity?
b) Water
- In an isobaric process, which of the following remains constant?
c) Pressure
Which thermodynamic process occurs at constant temperature?
b) Isothermal
What is the difference between enthalpy (ΔH) and internal energy (ΔE) in thermodynamics?
Internal Energy focuses on the energy inside the system. Enthalpy focuses on the energy inside the system plus the work done to volume changes at constant pressure.
