chemical equilibrium

Question 1

A chemical reaction is in equilibrium when…

Answer 1

A chemical reaction is in equilibrium when the composition of the
reactants and products remains constant indefinitely.

Question 2

what does this capital K represent

Answer 2

The equilibrium constant (K) characterises the equilibrium composition of the reaction mixture.

Question 3

what can the value of the equilibrium constant indicate

Answer 3

The value of an equilibrium constant indicates the position of
equilibrium.

Question 4

what are taken as constant and given a value of 1 in the equilibrium expression.

Answer 4

The concentrations of pure solids and pure liquids at equilibrium are taken as constant and given a value of 1 in the equilibrium expression.

Question 5

what does the numerical value of the equilibrium depend on

Answer 5

The numerical value of the equilibrium constant depends on the reaction temperature and is independent of concentration and/or
pressure.

Question 6

what is the effect of temperature on K in endothermic reactions

Answer 6

For endothermic reactions, a rise in temperature causes an increase in K and the yield of the product is increased.

Question 7

what is the effect of tempreature on K for exothermic reactions

Answer 7

For exothermic reactions, a rise in temperature causes a decrease in K and the yield of the product is decreased.

Question 8

what does the presence of a catalyst do to the equilibrium constant

Answer 8

The presence of a catalyst does not affect the value of the equilibrium
constant.

Question 9

what is the equilibrium in water and aqueous solutions

Answer 9

In water and aqueous solutions there is an equilibrium between the
water molecules and hydronium (hydrogen) and hydroxide ions

Question 10

is water amphoteric and what does that mean

Answer 10

Water is amphoteric (can react as an acid and a base).

Question 11

what is the dissociation constant for the ionisation of water known as

Answer 11

The dissociation constant for the ionisation of water is known as the ionic product

Question 12

does temp effect the value of the ionic product

Answer 12

The value of the ionic product varies with temperature.

Question 13

what do the Brønsted-Lowry definitions of acids and bases state

Answer 13

The Brønsted-Lowry definitions of acids and bases state that an acid
is a proton donor and a base is a proton acceptor

Question 14

how is a conjugate base formed

Answer 14

For every acid there is a conjugate base, formed by the loss of a
proton.

Question 15

how is a conjugate acid formed

Answer 15

For every base there is a conjugate acid, formed by the gain of a
proton.

Question 16

how do strong acids and bases dissociate

Answer 16

Strong acids and strong bases are completely dissociated into ions in
aqueous solution

Question 17

how do weak acids and bases dissociate

Answer 17

Weak acids and weak bases are only partially dissociated into ions in
aqueous solution.

Question 18

what are some examples of strong acids

Answer 18

Examples of strong acids include hydrochloric acid, sulfuric acid and
nitric acid.

Question 19

what are some examples of weak acids

Answer 19

Ethanoic acid, carbonic acid and sulfurous acid are examples of
weak acids.

Question 20

what are strong bases

Answer 20

Solutions of metal hydroxides are strong bases.

Question 21

what are examples of weak bases

Answer 21

Ammonia and amines are examples of weak bases.

Question 22

how can the weakly acidic nature of solutions of carboxylic acids, sulfur dioxide and carbon dioxide can be explained

Answer 22

The weakly acidic nature of solutions of carboxylic acids, sulfur dioxide and carbon dioxide can be explained by reference to equations showing the equilibria.

Question 23

how can the weakly alkaline nature of a solution of ammonia or amines can be explained

Answer 23

The weakly alkaline nature of a solution of ammonia or amines can be explained by reference to an equation showing the equilibrium.

Question 24

equimolar solutions of weak and strong acids….

Answer 24

Equimolar solutions of weak and strong acids (or bases) have different pH values, conductivity, and reaction rates, but the stoichiometry of reactions are the same.