Thermodynamics
Problem Set 01
Problem 1.
A thermodynamic system is defined as a chosen space to be observed and distinguished from its surroundings. A system can be clearly defined with constituents, parameters, nest of forces and possible constraints. The constituents are referred to the identifiable amount of matter in the system; the parameters contain the system with a boundary; nest of forces describe the interactions within the system and constraints which may have an affect on the parameters in the system.
Table 1 below shows examples for different systems.
System
Constituents
Parameters
Internal forces
Constraints
Open system of air with water vapour
Water molecules, H2O
A selected fixed volume of air
Interaction forces inside the molecule
None
Heart
Blood with oxygen haemoglobin
The heart organ boundary, volume of heart which is variable with heart beat
Interaction with oxygen and haemoglobin
None
Nuclear power-plant
Uranium, water and steam, products of fission reaction
Volume of containment for reactor and water
Forces between water molecules, along with fission molecules
Fission reaction mechanism with uranium
Automotive engine
Fuel-air mixture and products of combustion
Engine container, valve
Forces between molecules in the air-fuel mixture
Combustion reaction within the air-fuel mixture
Jet engine
Air, fuel, air-fuel mixture, products of combustion and aircraft
A large surrounding volume of air
Forces between molecules
A reaction between air and fuel mechanism
Table 1
Problem 2.
Table 2 below shows us the summary of each system and their specifications.
System
Constituents
Parameters
Internal forces
Constraints
(a)
Air having a variable range within the parameter
Volume of the tire having a variable range
Interaction forces between the air molecules.
None
(b)
Red wine, from zero to max volume of bottle
Volume of the bottle has a fixed value
Wine molecules have interaction forces between each other.
None
(c)
Water molecules, H2O, and spaghetti, both having a fixed amount
Volume of the pot has a fixed value
Water and spaghetti molecules experience forces between each other.
None
(d)
Gas-air mixture also with the products of combustion, having a variable amount
Volume of container with a fixed value
Molecules interact with each other.
Forces between gasoline and air creates reaction
Table 2
There are some interactions that occur at each system boundary. For system (a) there is an exchange in air molecules from the pump to the tire. In system (b) there is exchange in wine molecules into the wine bottle. In system (c) there is a change in system constituents when the spaghetti is added to the system through the boundary, and also the water molecules escaping the system via evaporation. In system (d) the container is isolated so there is no interaction. However it may depend on the material if the container allows for radiation to go through, so there may be an interaction if defined so.
Problem 3.
Solution:
(a) Systems A, B and C have the same parameters, constraints and experience the same internal and external forces; but they do not have the same types of constituents. Therefore they are not identical. However, they all have pretty much the same elements that when added together they could be similar; it’s all depends on how we define it. In order to make systems A, B and C identical we define the constituents to be D2, O, T, n and D2O. Along that we say the constraints are the chemical and nuclear reactions that occur as D2+O=D2O and T+n= D2 which allows for the constituents to transform from one type to another. This way we can say that the systems are identical. They are in a different state because they at one instant of time they are not experiencing the same directional motion and their amounts vary in constituents.
(b) To define the system so that systems A and B are the same the constituents need to be D2, O and D2O and the constraint needs to include the reaction of D2+O=D2O. This way the systems A
