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

Guess

A

BC

BC

C

Reasonable (Y/N)

4

1.85

0.45

3.15

4.15

(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 = 1.85 - 4.0 = -2.15 (Since the equilibrium amount is less than the initial amount we include a '-' to indicate is A reacting.)

For BC: [BC]equilibrium - [BC]initial = 0.45 - 2.6 = -2.15 (Since the equilibrium amount is less than the initial amount we include a '-' to indicate is BC reacting.)

For AB: [AB]equilibrium - [AB]initial = 3.12 - 1.0 = +2.15 (Since the equilibrium amount is higher than the initial amount we include a '+' to indicate is AB forming.)

For C: [C]equilibrium - [C]initial = 4.15 - 2.0 = +2.15 (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

-2.15

-2.15

+2.15

+2.15

Equilibrium

1.85

0.45

3.15

4.15

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

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

One important criteria is the stoichiometry in the chemical equation must be the same as the stoichiometry of the Change row: 1 A : 1 BC : 1AB : 1 C. In this case it is.

This is a reasonable guess in terms of the stoichiometry of the reaction.

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