When a sample of NO2(g) (5.641 mol) is placed in 360.0 L reaction vessel at 716.0 K and allowed to come to equilibrium the mixture contains 3.412 mol of NO(g). What is the equilibrium concentration (mol/L) of NO(g)?
When a sample of PCl5(g) (1228 grams) is placed in 270.0 L reaction vessel at 906.0 K and allowed to come to equilibrium the mixture contains 2.079 mol of PCl3(g). What concentration (mol/L) of PCl5(g) reacted?
what is the difference between equilibrium concentration and concentration reacted
A+B><C+D
A and B are reacting to make C and D. C and D are reacting to make A and B. When the reaction rates both ways are the same, or equal, the reaction is said to be in equilibrium. The equilibrium concentrations are the moles of A, B, C, and D divided by the volume.
This is not the initial concentration. Pretend you had some A, some B, and Some C, and no D. You have then four intial concentrations (one zero). The reaction proceeds to a final equilibrium, and reaches concentrations of A, B, C, D as determined by conditions. The amount reacted is different than the initial amount, and in fact, it can be + or -, as it could be less or more than was present initially.
To answer both of these questions, we can use the concept of equilibrium and the equation for calculating equilibrium concentrations.
In a chemical reaction, when both the forward and reverse reactions are occurring at the same rate, we say that the reaction has reached equilibrium. At equilibrium, the concentrations of all reactants and products remain constant over time.
The equilibrium constant expression (Kc) for a reaction is given by the ratio of the concentrations of the products to the concentrations of the reactants, each raised to the power of their respective stoichiometric coefficients. The general formula is:
Kc = ([Products])^m / ([Reactants])^n
Now, let's apply this concept to the given questions.
Question 1:
Equilibrium equation: 2NO2(g) ⇌ 2NO(g) + O2(g)
Given: [NO2] = 5.641 mol and [NO] = 3.412 mol
We need to find the equilibrium concentration of NO(g).
As per the equilibrium equation, the stoichiometric coefficient of NO(g) is 2. Therefore, we can say that [NO] = 2x, where x is the equilibrium concentration of NO(g).
Using this information, we can set up the equation:
(3.412 mol) = 2x
Solving for x, we find x = 1.706 mol
So, the equilibrium concentration of NO(g) is 1.706 mol/L.
Question 2:
Equilibrium equation: PCl5(g) ⇌ PCl3(g) + Cl2(g)
Given: [PCl5] = 1228 g and [PCl3] = 2.079 mol
We need to find the concentration of PCl5(g) that reacted.
As per the equation, the stoichiometric coefficient of PCl5(g) is 1. Therefore, we can say that [PCl5] = x, where x is the concentration of PCl5(g) that reacted.
Using this information, we can set up the equation:
(2.079 mol) = x
Solving for x, we find x = 2.079 mol/L
Therefore, the concentration of PCl5(g) that reacted is 2.079 mol/L.
In summary, the equilibrium concentration refers to the concentration of a substance in a reaction mixture at equilibrium, while the concentration reacted refers to the amount of a substance that has been consumed or converted in the reaction.