KA5- Equilibrium

Question 1

What is the definition of equilibrium?

Answer 1

when the composition of the reactants and roducts remains constant indefanitly

Question 2

What does K represent?

Answer 2

indicates the position of equilibrium
no units

Question 3

what is not included in equilibrium constant calculations?

Answer 3

concentrations of pure solids and pure liquids are constant so are not included

Question 4

What does the numerical value of equilibrium depend on?

endo and exo

Answer 4

the reaction temperature being changed
* for endothermic reactions a rise in temperature increases the K value (yield of product is increased)
* for exothermic reactions a rise in temperature decreases the K value (yield of product is decreased

Question 5

Does the presence of a catalyst affect K?

Answer 5

No

Question 6

What can also be used in place of H+ ions?

Answer 6

Hydrodium ions (H30+)

Question 7

Water can act as a ____ or a ____

Answer 7

acid or a base (it is said to be amphoteric)

Question 8

What is represented through Kw

Answer 8

the dissosiation constant for the ionisation of water is known as the ionic product and is represented as by Kw

Question 9

What is Kw as 25 celsius

Answer 9

1 x 10^-14

Question 10

pH= -log(10)[H3O+] to…

Answer 10

[H3O+]+10^-pH

Question 11

In water and aqueous solutions with the pH of 7 what are the concentrations of H3O+ and OH-

Answer 11

both 10^-7 mol l^-1 at 25 degrees

Question 12

What equation do you use if the concentrations of OH or H3O are known?

Answer 12

Kw or pH + pOH=14

Question 13

What are the Brønsted-Lowry definitions of acids and bases?

Answer 13

acid- proton donator
base- proton acceptor

Question 14

For every acid there is a ____, formed by the ____ of a proton.

Answer 14

conjugate base, loss

Question 15

For every base there is a ____, formed by the ____ of a proton

Answer 15

conjugate acid, gain

Question 16

Stong acids and ____ bases are ____ ____ into ions in a aqueous solution

Answer 16

strong, completely dissociated

Question 18

Weak bases and ____ acids are ____ ____ into ions in a aqueous solution.

Answer 18

weak, only partially dissociated

Question 19

Examples of strong acids are…

Answer 19

Hydrocholoric acid (HCl), Sulfuric acid and Nitric acid

Question 20

Examples of weak acids are…

Answer 20

Ethanoic acid, carbonic acid and sulfurous acid

Question 21

Strong bases are…

Answer 21

solutions of metal hydroxides

Question 22

Examples of weak bases are…

Answer 22

ammonia and amines

Question 23

What is Ka?

Answer 23

the acid dissociation constant
pKa=-log(10)Ka

Question 24

To work out the approximate pH of a weak acid you use,

Answer 24

pH=1/2pKa-1/2log(10)c
(c being the concentration)

Question 25

A ____ salt of a strong acid and a strong base dissolves in ____ to produce a ____ solution

Answer 25

soluble, water, neutral

Question 26

A soluble salt of a weak acid and a strong base dissolves in water t produce what?

Answer 26

An alkaline solution

Question 27

A soluble salt of a storng acid anf a weak base dissolves in water to produce what?

Answer 27

An acidic solution

Question 28

The name of the salt produced depends on what?

Answer 28

the parent acid and base

Question 29

Using the appropriate equilibria, the changes in ____ of hydronium and hydroxide ions of ____ solutions can be explained

Answer 29

concentations
salt

Question 30

What is a buffer solution?

Answer 30

is a solution in which the pH remains approx. constant when small amounts of acid, base or water are added

Question 31

An acid buffer consists of a solution of what?

Answer 31

weak acid and one of its salts made from a strong base

Question 32

In an acidic buffer solution the ____ acid provides ____ ions when these ions are removed by the addition of a small amount of ____. the salt of the weak acid provide the ____ ____ which can absorb excess ____ ions produced by the addition of a small amount of acid.

Answer 32

weak
hydrogen
base
conjugate bases
hydrogen

Question 33

A basic buffer consists of what?

Answer 33

a weak base and one of its salts

Question 34

in a basic buffer solution the … base removes … … ions and the … … provided by the salt supplies … ions when these are removed.

Answer 34

weak
excess hydrogen
conjugate acid
hydrogen

Question 35

What equation is used to find the pH of an acid buffer solution?

Answer 35

pH=pKa- log(10) {[acid/[base]}

Question 36

What are indicators?

Answer 36

weak acids

Question 37

What is K(In)?

Answer 37

the acid indicator dissociation constant. it has the following expression;
Kin=[H3O+][In-]/ [HIn]

Question 38

In ____ solution the ____ of an acid idicator is ____ from that of its ____ ____.

Answer 38

aqueous, different, conjugate base

Question 39

The colour of the indicator is determined by what?

Answer 39

The ratio of [HIn] to [In-]

Question 40

The theorectical point at which colour change occurs is when?

Answer 40

When hydromium ion concentation ([H3O+]) = K(In-)

Question 41

the colour change is assumed to be distinguishable when?

Answer 41

when [HIn] and [In-] differ by a factor of 10

Question 42

What is the expression used to determine the pH range using a indicator?

Answer 42

pH=pK(In) +/- 1