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6.
Response progress
Chemical reaction
v A A+v b B=v G G+v H H
In the formula, v is the stoichiometric number of each substance, which is a physical quantity of dimension 1
.
When the reaction did not occur (t = 0), the amount of material of the individual substances are n- 0A , n- oB , n- oG and n- oH ; reacted to t = t, the amount of substance in each substance are n- A , n- B , n- G and n- H
It can be seen that the progress of the reaction can be described as the ratio of the amount of the substance reduced by the reactant or the amount of the substance increased by the product to the stoichiometric number of each substance in the reaction formula
.
The unit of the reaction progress ξ is mol
.
The reaction progress can be zero, a positive integer, or a positive score, but it cannot be a negative number
ξ=1mol means that from the time when ξ=0, v A mol A and v B molB have been consumed, and v G mol G and v H mol H are generated
.
That is, based on vA A particles and vB B particles as a unit, 6.
02×10 23 unit reactions have been carried out
7.
Reversible pathway
Under ideal gas constant temperature conditions, expand from p1=16×10 5 Pa, V1=1×10 -3 m 2 to p2=1×10 5 Pa, V2=16×10 -3 m 3 , the system can be expanded by one expansion ( Expansion times (N=1), two expansion paths (N=2) to complete this thermodynamic process, or four expansion paths (N=4) or more expansion paths to complete this thermodynamic process (Figure 2 -4)
.
The pV line and the covered area of each expansion pathway are shown in Figure 2-5
Figure 2-4 Different ways of ideal gas constant temperature expansion
Figure 2-5 The pV lines and reversible paths of different paths of ideal gas constant temperature expansion
It can be found from Figure 2-5 that when the initial state and the final state are the same, the greater the number of expansions of the ideal gas N, the greater the area covered under the pV line
.
When the number of expansion N tends to infinity, the pV fold line approaches the pV=nRT curve, and the area covered under the pV fold line also approaches the area covered under the pV=nRT curve
The reversible path is a special path in which the absolute value of the work done by the system is the largest (indicated by Wr)
.
Each step in the reversible path is reversible, and the process completed by the reversible path is naturally reversible, so it is also called the reversible process
