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subwayrider
1) Combustion Reactions and CO
Carbon monoxide is released when carbon material is reacted, or burnt with sub-stoichiometric levels of Oxygen. This is most typically seen in car engines which can produce a very high ppmv of CO in their exhaust gas.
Here is the reaction scheme for carbon and oxygen:
(1) Cn + nO2 -> nCO2
(2) Cn + (n/2)O2 -> nCO
Therefore reaction (2) is preferred when less Oxygen is supplied.
As an interesting aside, the Claus process is used industrially to burn H2S (a highly toxic and unwanted chemical present in gas production) to create benign pure sulphur and water.
2) Why does Force have units of kg x m/s^2 ?
F = m x a
where, Force = F, mass = kg, acceleration = m/s2
Acceleration is the derivative of speed, the rate at which speed in m/s changes per second. i.e. m/s/s = m/s2
Therefore multiplying the units , F in kg.m/s2
3) Why does Work have units of kg x m^2/s^2?
Work is the instantaneous energy being applied to a system, in Watts,
W = F x d
Where F is the force applied in kg.m/s2 and distance is in m, thus kg.m2/s2
4) Why are ⌂T, ⌂V, ⌂P, etc. state functions, when q(heat) and w(work) are not?
I object of the use of the term q as heat when it is duty, heat is more enthalpy versus pressure because I'm an engineer, scientists disagree because they are morons, but this is a different problem which causes fist fights between engineers and scientists so lets stick to the question.
A state function is a property of the system which is only dependant upon the state of the system at an instantaneous point in time, they can be gauged at any point in time as a consequence and are at that instant in equilibrium. By contrast mechanical work and heating duty are process quantities that are dependant upon the transition between two equilibrium states.
5) Elaborate on enthalpy further than "a thermodynamic variable" or "H= E + PV"
Enthalpy allows you to track the impact of adding heat to a system whilst taking into account pressure and volume changes.
Note, E = internal energy
P = Pressure and
V = Volume
In effect a kW of heat added to the system increases the enthalpy of the system by said kW.
However, this kW will only directly translate into a thermal effect by increasing the internal energy of the system if it is held at constant pressure and volume. (isobaric and fixed volume). Therefore the equation is a method of explaining why adding a kW of energy to a system does not increase the heat by a kW.
Conversely - and perhaps more usefully - it allows one to gauge how manipulating the volume or pressure of a system will change it's internal energy without applying additional heating duty to the system.
It should be noted that internal energy is made up of a number of factors besides sensible heat such as entropy.
Enthalpy is a state function of the system even though it cannot be directly measured with an 'enthalpy gauge' therefore it must be calculated by experiment with a reference point of absolute zero temperature/pressure.