Chapter 16: Chemical Equilibrium

What is chemical equilibrium?

A state in which forward and reverse chemical reactions occur simultaneously at the same rate, with concentrations of reactants and products remaining constant.

when is equilibrium established in terms of reaction rates

equilibrium is established when rates of forward and reverse rxns are equal

when is equilibrium established in terms of concentration

when concentrations remain constant

Not all rxns are reversible, true or false?

false, all rxns are reversible and can go in either direction

when the position of equilibrium favors the products....

rxn reaches equilibrium only after almost all the reactant molecules are consumed

position of equilibrium favors the reactants....

when only small percentage of reactant molecules are consumed

What does the Law of Mass Action describe?

The relationship between a chemical equation and the concentrations of reactants and products.

Out of all the states of substances (solids, gases, liquids...), which ones are written in equilibrium expression?

ONLY gases and substances in solutions, NOT pure liquids and solids (they are constants)

What does a large equilibrium constant for concentrations (Keq) indicate?

It indicates that the system contains more products than reactants at equilibrium.

What does a small equilibrium constant for concentrations (Keq) indicate?

It indicates that the system contains more reactants than products at equilibrium.

if K is less than 1 what does that mean?

reverse rxn is favored, reactants are favored

if K is greater than 1 what does that mean?

forward rxn is favored, products are favored

What happens to K in a forward exothermic reaction when temperature increases?

K decreases with increasing temperature.

What happens to K in a forward endothermic reaction when temperature increases?

K increases with increasing temperature.

What is dynamic equilibrium?

A state where forward and reverse reactions occur at the exact same rate.

what is hemoglobin?

protein that reacts with oxygen and carries it through the bloodstream

Concentrations of Hb, O2, and HbO2 are interdependent, true or false?

True

Describe oxygen transport in the lungs

High concentration of O2, equilibrium shifts to the right, Hb and O2 combine to make more HbO2

describe oxygen transport in the muscles

low concentration of O2, equilibrium shifts to the left, HbO2 dissociates increasing amount of free O2

What is Le Châtelier's Principle?

If stress is applied to a system in equilibrium, it will readjust to reduce the stress.

if more products have been produced from a disruption, equilibrium is said to have shifted....

right

if more reactants form from a disruption, equilibrium is said to have shifted...

left

How does concentration affect equilibrium?

The system will shift in the direction that consumes some of the added component.

How does temperature affect equilibrium?

Increasing temperature favors endothermic reactions; decreasing temperature favors exothermic reactions.

What effect does pressure have on equilibrium?

addition of non reactive gas does not affect the equilibrium position

How does decreasing volume affect equilibrium?

It shifts equilibrium toward the side with fewer moles of gas.

how does the addition of catalysts affect equilibrium?

they dont change position of equilibrium, but it is established more quickly because of them

the concentration of gas in a mixture is no proportional to its partial pressure, true or false?

False it is proportional

the value of the equilibrium constant will always remain the same as long as what is kept constant?

temperature, it is independent of initial amounts of reactants and products

What is the reaction quotient (Q)?

A measure used to determine the direction in which a reaction will reach equilibrium when the reaction mixture is not at equilibrium.

What does it mean if Q < K?

The reaction will proceed to the right, toward products.

What does it mean if Q > K?

The reaction will proceed to the left, toward reactants.

what does it mean if Q = K?

rxn is at equilibrium

What is a (R)ICE table used for?

To calculate equilibrium concentrations by organizing (I) initial concentrations, (C) changes, and (E) equilibrium concentrations.

What does Kp represent?

The equilibrium constant in terms of partial pressures.

How do you determine the direction of a reaction using Q and K?

Compare Q to K: if Q < K, shift right; if Q > K, shift left; if Q = K, at equilibrium.

What is fetal hemoglobin's advantage over adult hemoglobin?

Fetal hemoglobin (HbF) has a greater oxygen-binding affinity than adult hemoglobin (HbA), allowing for more efficient oxygen transfer from mother to fetus.

when is it valid to approximate equilibrium concentration?

when you do ((approximate x)/(initial concentration))*100 and the answer is less than 5%