Chemistry Chemical Equilibria

Question 1

When there is no net change in the ___ of the products and reactants during a reversible chemical reaction, equilibrium exists

Answer 1

concentrations

Question 2

Given 2A ->

Answer 2

reaction

Question 3

Since k sub f and k sub r are both constants, this equation may be rewritten as
k sub c = [B][C]/[A]^2
where k sub c is called the equilibrium ___ and the subscript c indicates that it is in terms of concentration

Answer 3

constant

Question 4

When dealing with gases the equilibrium constant is referred to as K sub p, and the subscript p indicates that is in terms of ___. For dilute solutions, K sub c and K sub eq are used interchangeably.

Answer 4

partial pressure

Question 5

While the forward and reverse reaction rates are equal at equilibrium, the ___ of the reactants and products usually are not equal. This means that the forward and reverse rate constants, k sub f and k sub r, respectively, are also usually unequal

Answer 5

molar concentrations

Question 6

k sub f [A]^2 = k sub r [B][C]
k sub g = k sub r([B][C]/[A]^2)
Given aA + bB ->

Answer 6

expression

Question 7

Pure solids and liquids do not appear in the equilibrium ___
K sub eq is characteristic of a given system at a given temperature
If the value of k sub eq is much larger than 1 an equilibrium mixture of reactants and products will contain very little of the reactants compared to the products
If the value of K sub eq is much smaller than 1 (i.e., less than 0.1), an equilibrium mixture of reactants and products will contain very little of the products compared to the reactants
If the value of K sub eq is close to 1, an equilibrium mixture of products and reactants will contain approximately equal amounts of reactants and products

Answer 7

constant expression

Question 8

Depending on the actual rates of the forward and reverse reactions, ___ might be achieved in microseconds or millennia

Answer 8

equilibrium

Question 9

At any point in time during a reaction, we can measure the concentrations of all of the reactants and products and calculate the ___ according to the following equation

Answer 9

reaction quotient

Question 10

Q = [C]^c[D]^d/[A]^a[B]^b
This equation looks identical to the equation for K sub eq. It is the same form, but the information it provides is quite different. While the ___ used for the law of mass action are equilibrium (constant) concentrations, the concentrations of the reactants and product are not constant when calculating a value for Q of a reaction

Answer 10

concentration

Question 11

Q < k sub eq, then the forward reaction has not yet reached equilibrium
There is a greater concentration of reactants (and smaller concentration of products) than at equilibrium
The forward rate of reaction is increased to restore equilibrium
Q= K sub e q, then the reaction is in dynamic equilibrium
The reactants and products are present in equilibrium proportions
The forward and reverse rates of reaction are equal
Q > K sub eq, then the forward reaction has exceeded equilibrium
There is a greater concentration of ___ (and smaller concentration of reactants) than at equilibrium
the reverse rate of reaction is increased to restore equilibrium

Answer 11

products

Question 12

Any reaction that has not yet reached the ___, as indicated by Q < k sub eq, will continue spontaneously in the forward direction (consuming reactants to form products until the equilibrium ratio of reactants and products is reached

Answer 12

equilibrium state

Question 13

Any reaction in the equilibrium state will continue to react in the forward and reverse directions, but the reaction rates for the forward and ___ will be equal, and the concentrations of the reactants and products will be constant, such that Q = k sub eq

Answer 13

reverse reactions

Question 14

A ___ that is beyond the equilibrium state, as indicated by Q > K sub eq, will proceed in the reverse direction (consuming products to form reactants) until the equilibrium ratio of reactants and products is reached again

Answer 14

reaction

Question 15

Once a reaction is at ___, any further movement in either the forward direction (resulting in a increase in products) or in the reverse direction (resulting in the reformation of reactants) will be nonspontaneous

Answer 15

equilibrium

Question 16

Q < K sub eq: delta G < 0, ___ proceeds in forward direction
Q=K sub eq: delta G = 0, reaction is in dynamic equilibrium
Q > k sub eq, delta G > 0: reaction proceeds in reverse direction

Answer 16

reaction

Question 17

If an external stress is applied to a ___ currently at equilibrium, the system will attempt to adjust itself to partially offset the stress

Answer 17

system

Question 18

Given A + B ->

Answer 18

concentration

Question 19

___ and volume are inversely related. An increase in the pressure of a system will shift the equilibrium so as to decrease the number of moles of gas present. This reduces the volume of the system and relieves the stress of the increased pressure

Answer 19

pressure

Question 20

N2(g) +3H2(g) ->

Answer 20

molecules

Question 21

Not only does temperature change alter the position of the ___, it also alters the numerical value of the equilibrium constant

Answer 21

equilibrium

Question 22

___ is the only thing that will affect the value of K, equilibrium constant. In contrast, changes in the concentration of a species in the reaction, in the pressure, or in the volume alter the position of the reaction quotient without changing the numerical value of the equilibrium constant itself

Answer 22

temperature

Question 23

The process of ___, like other reversible chemical and physical changes, tends toward equilibrium

Answer 23

solvation

Question 24

Immediately after a ___ has been introduced into a solvent, most of the change taking place is dissociation because no dissolved solute is initially present. However, according to Le Chatelier’s principle, as solute dissociates, the reverse reaction (precipitation of the solute) also begins to occur

Answer 24

solute

Question 25

A slightly soluble ionic solid exists in equilibrium with its saturated solution. The ion product (Q sub sp) of a compound in solution is defined as follows (note that solids and pure liquids are not included in the calculations for Q or K):
Q sub sp = [A]^m[B]^n
The same expression for a saturated solution at equilibrium defines the ___
K sub sp = [A]^m[B]^n in a saturated solution
However, Q sub sp is defined with respect to initial concentrations and does not necessarily represent either an equilbrium or a saturated solution, while K sub sp does Q sub sp, like the reaction quotient, indicates where the dissolution is with respect to equilibrium

Answer 25

solubility product constant

Question 26

Each ___ has its own distinct K sub sp at a given temperature.

Answer 26

salt

Question 27

If at a given temperature a salt’s Q sub sp is equal to its K sub sp, the solution is saturated, and the rate at which the salt dissolves equals the rate at which it precipitates out of solution. If a salt’s Q sub sp exceeds its K sub sp, the solution is supersaturated (holding more salt than it should be able to at a given temperature) and unstable. Consequently, the reverse reaction will be favored. If the ___ solution is disturbed by adding more salt, other solid particles or jarring the solution by a sudden decrease in temperature, the solid salt will precipitate until Q sub sp equals the K sub sp. If Q sub sp is less than K sub sp, the solution is unsaturated and no precipitate will form, and the forward reaction will be preferred

Answer 27

supersaturated

Question 28

The quantity of a salt that can be ___ is considerably reduced when it is dissolved in a solution that already contains one of its ions rather than in a pure solvent. This reduction in solubility is called the common ion effect

Answer 28

dissolved