# The concentration of B at equilibrium

• JessicaHelena
In summary, the given problem involves a reaction with 2.00 moles of A, 3.00 moles of B, and a 6.00L container. At equilibrium, the concentration of A is given as 0.246 mol/L. Using the concept of stoichiometry and an ICE table, it can be determined that B is the limiting reactant and its concentration at equilibrium can be calculated to be 0.123 mol/L. The concentration of C and the value of K are not needed for this calculation.
JessicaHelena

## Homework Statement

For the reaction given below, 2.00 moles of A and 3.00 moles of B are placed in a 6.00L container.
A(g) + 2B(g) --> C(g)
At equilibrium, the concentration of A is 0.246 mol/L. What is the concentration of B at equilibrium?

## Homework Equations

for aA+bB-->cC,
K = [C]^c/([A]^a[ B]^b)

c=n/V

## The Attempt at a Solution

Frankly, I'm not sure what to do here. The LR is B since using all 3.00 moles of B, we'd only need 1.5 moles of A, but that's when the reaction goes to completion and we don't know if it does. Also, we are not given C's concentration or the K value... What can I do here?

Last edited by a moderator:
JessicaHelena said:
The LR is B since using all 3.00 moles of B, we'd only need 1.5 moles of A, but that's when the reaction goes to completion and we don't know if it does.
That's something you can figure out

JessicaHelena said:
Also, we are not given C's concentration or the K value...
It is not given because it is not needed.

JessicaHelena said:
What can I do here?
What happens to A and B when you mix them? What is the relation between the concentrations of A, B and C?

how can I figure at which point the experiment stops — I'm still not so sure.

The amount of A and B decrease to produce C.

concentrations of A:B:C = # of moles of A:B:C

Think in terms of a simple stoichiometry.

Chestermiller
So then at equilibrium, there'd be 0.246 mol/L of A, and 0.246 x 2 mol/L of B and 0.246 mol/L of C?

No. you have the concentration of A, and the volume. How many moles of A are there?
So how many moles of A have reacted?
How many moles of B have reacted, and how many are left?
What is the concentration of B?
Have you heard of an ICE table?

## 1. What is the definition of equilibrium in regards to the concentration of B?

Equilibrium in regards to the concentration of B refers to the point at which the rate of the forward reaction is equal to the rate of the reverse reaction, resulting in no net change in the concentration of B over time.

## 2. How is the equilibrium concentration of B determined?

The equilibrium concentration of B is determined by the initial concentrations of reactants, the stoichiometry of the reaction, and the equilibrium constant (K) for the reaction.

## 3. What factors can affect the equilibrium concentration of B?

The equilibrium concentration of B can be affected by changes in temperature, pressure, or the concentrations of reactants or products. The addition or removal of a catalyst can also impact the equilibrium concentration.

## 4. How does Le Chatelier's principle relate to the equilibrium concentration of B?

Le Chatelier's principle states that when a system at equilibrium is subjected to a stress, it will shift to counteract the stress and re-establish equilibrium. This can affect the equilibrium concentration of B by changing the direction of the reaction or altering the concentrations of reactants and products.

## 5. Can the equilibrium concentration of B ever be reached in a real-life scenario?

No, the equilibrium concentration of B is an idealized concept and can never be truly reached in a real-life scenario. However, a system can approach equilibrium and maintain a steady state with minimal changes in the concentration of B over time.

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