A table used to organise the Initial concentration or partial pressure, the Change in concentration or partial pressure and the Equilibrium concentration or partial pressure of each species in a reversible reaction.

Why must the Change row of an ICE table use stoichiometric coefficients as multipliers on x ?

Because reactants and products are consumed or produced in the molar ratios given by the balanced equation . Using the stoichiometric coefficient as a multiplier ensures that the changes in each species are consistent with one another — if one reactant decreases by x , a product with a coefficient of 2 must increase by 2 x .

True or False? The equilibrium row of an ICE table is calculated by adding the Initial and Change values for each species.

True. The equilibrium concentration or partial pressure of each species is the sum of its initial value and its change (which may be negative for a species that is consumed).

How can you check whether your calculated equilibrium concentrations are correct?

Substitute the calculated equilibrium concentrations or partial pressures back into the equilibrium expression and evaluate K . If the result is close to the given value of K , the calculation is correct.

True or False? An ICE table can only be used with concentrations in M, not with partial pressures in atm.

False. An ICE table can be used to track concentrations (M), amounts (mol), or partial pressures (atm) — the appropriate quantity depends on whether K c or K p is being used.

In an ICE table, species that are consumed during the reaction have a Change of .......... multiplied by the appropriate stoichiometric coefficient, while species that are produced have a Change of .......... multiplied by the appropriate stoichiometric coefficient.

In an ICE table, species that are consumed during the reaction have a Change of −*x multiplied by the appropriate stoichiometric coefficient, while species that are produced have a Change of + x * multiplied by the appropriate stoichiometric coefficient.

Define chemical equilibrium .

The state of a reversible reaction in which no observable changes occur to the number of particles (or concentrations) of any species over time. The forward and reverse reactions continue at equal rates.

How is a particulate diagram of a system at equilibrium used to calculate K c ?

Count the particles of each species and use the given scale and container volume to convert them to molar concentrations. Substitute those concentrations into the K c expression — products raised to their stoichiometric powers divided by reactants raised to their stoichiometric powers.

True or False? The reaction quotient Q can only be calculated when the system is at equilibrium.

False. Q uses the same expression as K , but its value can be determined from concentrations or partial pressures at any point during the reaction, not just at equilibrium. At equilibrium, Q = K .

A particulate diagram shows 3 particles of X and 6 particles of Y in a 1.00 L vessel at equilibrium for the reaction X (g) ⇌ 2Y (g). What is K c ?

Concentrations: [X] = 3.00 M, [Y] = 6.00 M. K c = [Y] 2 / [X] = (6.00) 2 / 3.00 = 36.00 / 3.00 = 12.0

True or False? When reading a particulate diagram, the size of the container and the scale used (moles or concentration per particle) must be taken into account before calculating K or Q .

True. The number of particles shown must be converted to concentration using the given scale and container volume. A 2.00 L vessel changes concentrations by a factor of two compared to a 1.00 L vessel, even if the particle count is the same.

A particulate diagram can be used to calculate Q by substituting the current concentrations into the equilibrium expression. At equilibrium, Q .......... K .

A particulate diagram can be used to calculate Q by substituting the current concentrations into the equilibrium expression. At equilibrium, Q equals K .

AP®ChemistryCollege BoardFlashcardsUnit 7: EquilibriumEquilibrium Representation & Calculations

Equilibrium Representation & Calculations (College Board AP® Chemistry): Flashcards

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FrontCalculating Equilibrium Concentrations
Define ICE table.

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Define ICE table.
A table used to organise the Initial concentration or partial pressure, the Change in concentration or partial pressure and the Equilibrium concentration or partial pressure of each species in a reversible reaction.
Why must the Change row of an ICE table use stoichiometric coefficients as multipliers on x?
Because reactants and products are consumed or produced in the molar ratios given by the balanced equation. Using the stoichiometric coefficient as a multiplier ensures that the changes in each species are consistent with one another — if one reactant decreases by x, a product with a coefficient of 2 must increase by 2x.
True or False?
The equilibrium row of an ICE table is calculated by adding the Initial and Change values for each species.
True.
The equilibrium concentration or partial pressure of each species is the sum of its initial value and its change (which may be negative for a species that is consumed).
How can you check whether your calculated equilibrium concentrations are correct?
Substitute the calculated equilibrium concentrations or partial pressures back into the equilibrium expression and evaluate K. If the result is close to the given value of K, the calculation is correct.
True or False?
An ICE table can only be used with concentrations in M, not with partial pressures in atm.
False.
An ICE table can be used to track concentrations (M), amounts (mol), or partial pressures (atm) — the appropriate quantity depends on whether K_c or K_p is being used.
In an ICE table, species that are consumed during the reaction have a Change of .......... multiplied by the appropriate stoichiometric coefficient, while species that are produced have a Change of .......... multiplied by the appropriate stoichiometric coefficient.
In an ICE table, species that are consumed during the reaction have a Change of −*x multiplied by the appropriate stoichiometric coefficient, while species that are produced have a Change of +x* multiplied by the appropriate stoichiometric coefficient.
Define chemical equilibrium.
The state of a reversible reaction in which no observable changes occur to the number of particles (or concentrations) of any species over time. The forward and reverse reactions continue at equal rates.
How is a particulate diagram of a system at equilibrium used to calculate K_c?
Count the particles of each species and use the given scale and container volume to convert them to molar concentrations. Substitute those concentrations into the K_c expression — products raised to their stoichiometric powers divided by reactants raised to their stoichiometric powers.
True or False?
The reaction quotient Q can only be calculated when the system is at equilibrium.
False.
Q uses the same expression as K, but its value can be determined from concentrations or partial pressures at any point during the reaction, not just at equilibrium. At equilibrium, Q = K.
A particulate diagram shows 3 particles of X and 6 particles of Y in a 1.00 L vessel at equilibrium for the reaction X (g) ⇌ 2Y (g). What is K_c?
Concentrations: [X] = 3.00 M, [Y] = 6.00 M.
K_c = [Y]² / [X] = (6.00)² / 3.00 = 36.00 / 3.00 = 12.0
True or False?
When reading a particulate diagram, the size of the container and the scale used (moles or concentration per particle) must be taken into account before calculating K or Q.
True.
The number of particles shown must be converted to concentration using the given scale and container volume. A 2.00 L vessel changes concentrations by a factor of two compared to a 1.00 L vessel, even if the particle count is the same.
A particulate diagram can be used to calculate Q by substituting the current concentrations into the equilibrium expression. At equilibrium, Q .......... K.
A particulate diagram can be used to calculate Q by substituting the current concentrations into the equilibrium expression. At equilibrium, Q equals K.

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