Here is why the this set of equilibrium amounts for A, BC, AB and C is unreasonable.

Guess

A

BC

BC

C

Reasonable (Y/N)

5

4.2

2.8

1.2

2.2

(Yes/No)

In this guess the Change (the amounts reacting and forming) can be determined for A, BC, AB and C by comparing the equilibrium amount of each species to the initial amount.

For A: [A]equilibrium - [A]initial = 4.2 - 4.0 = +0.2 (Since the equilibrium amount is higher than the initial amount we include a '+' to indicate is A forming.)

For BC: [BC]equilibrium - [BC]initial = 2.8 - 2.6 = +0.2 (Since the equilibrium amount is higher than the initial amount we include a '+' to indicate is BC forming.)

For AB: [AB]equilibrium - [AB]initial = 1.2 - 1.0 = +0.2 (Since the equilibrium amount is higher than the initial amount we include a '+' to indicate is AB forming.)

For C: [C]equilibrium - [C]initial = 2.2 - 2.0 = +0.2 (Since the equilibrium amount is higher than the initial amount we include a '+' to indicate is C forming.)

Experiment #7

[A]

[BC]

[BC]

[C]

Initial

4.0

2.6

1.0

2.0

Change

+0.2

+0.2

+0.2

+0.2

Equilibrium

4.2

2.8

1.2

2.2

The Change does follows the stoichiometry of the balanced chemical equation;

A(g) + BC(g) ---> AB(g) + C(g)

but there is a major problem, both the reactants and the products are increasing the amounts at equilibrium. That is NOT possible. If the equilibrium amounts of the reactants is higher, the equilibrium amounts of the products must be smaller.

This is an unreasonable guess.

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