5.1.3 Acids, Bases and Buffers

Question 1

acids dissociate and release ….

Answer 1

H+ ions

Question 2

Alkalis dissociate and release…..

Answer 2

OH- ions in solution

Question 3

Bronsted-Lowry Acid

Answer 3

a species that donates a proton

Question 4

Bronsted- Lowry base

Answer 4

species that accepts a proton

Question 5

conjugate acid-base pairs

Answer 5

an acid and a base that can become each other through the transfer of a H+ /proton

Question 6

Hydronium ion

Question 7

monobasic

Answer 7

when one mole of acid dissociates to form one mole of H+ ions/protons

acids that release one proton into solution. Has one H that can be replaced.

Question 8

example of mono basic acids

Answer 8

HCl, CH3COOH

Question 9

dibasic acid, example

Answer 9

when one mole of acid dissociates to form 2 moles of H+/ protons

An acid that contains two replaceable hydrogen atoms per molecule of the acid - produces 2 H+ ions

H2CO3, H2SO4

Question 10

tribasic

Answer 10

when one mole of acid dissociates to form 3 moles of H+/protons

Question 11

why is CH3COOH mono basic ?

Answer 11

organic acids don’t replace any hydrogen atoms from the carbon chain

Question 12

acid + carbonate

Answer 12

salt and water and co2 (carbonates are bases)

Question 12

acid + metal

Answer 12

salt + hydrogen

Question 13

why is solid carbonate included in the ionic equation?

2H+ + CuCO3 (s) —> Cu 2+ (aq) + H20(l) + CO2 (g)

Answer 13

it changes state to a gas, which is included in an ionic equation

Question 14

what does pH measure?

Answer 14

the concentration of H+ ions in solution

Question 14

hydrogen ion concentrations have a large range of values, what method makes it a more manageable scale?

Answer 14

negative log (10^-)

Question 15

equation to find pH from H+ concentration

Answer 15

pH = -log (H+)

Question 16

equation to find H+ ion concentration from pH value

Answer 16

[H+] = 10 to the minus pH

Question 17

how does a change in pH by 1 affect H+ ion concentration?

Answer 17

x 10 difference

Question 18

How would you dilute a solution from 1 to 4 pH?

Answer 18

changes by pH of 3 so dilute by 10x10x10 = 1000 times

Question 19

How many more H+ ions does a solution of pH 1 have compared to ph 14?

Answer 19

10 to the power of 13

Question 20

when calculating pH of a strong, monobasic acid, why is H+ equal to the concentration of the acid?

Answer 20

amount of H + ions determines concentration and if strong acids completely dissociate their H+ ions , thats equal to concentration

Question 21

What is the version of the equilibrium constant used in acid-base equilibria?

Answer 21

acid dissociation constant (Ka)

Question 22

What does the Ka value measure?

Answer 22

the amount a weak acid dissociates. strong acids fully do.

Question 23

formula of Ka?

Answer 23

Ka = concentration of products / concentration of reactants

Question 24

what does a larger Ka value mean? and why?

Answer 24

more dissociation so stronger acid, because for equilibrium to be further right, number at top (concentration of ions) needs to be bigger than bottom (concentration of acid)

Question 25

what factor changes equilibrium constant Ka?

Answer 25

temperature - affects all equilibrium constants

Question 26

Ka values are hard to compare, so what negative algorithm value is used?

Answer 26

pKa

Question 27

pKa =

Answer 27

-log Ka

Question 28

How can you find ka from pKa?

Answer 28

10 to the -pKa

Question 29

compare the size of ka and pKa in a strong acid

Answer 29

stronger the acid, larger Ka value because more dissociation, smaller the pKa

Question 30

compare the size of Ka and pKa in a weak acid

Answer 30

weaker the acid, smaller the Ka, bigger the pKa

Question 31

water acts as both an acid and as a abase, show its acid base equilibrium

Answer 31

H20 + H20 ---> H30+ + OH-

Question 32

what is the acid dissociation constant for water?

Answer 32

Ka = [H+ (aq)] [OH- (aq)] / [H2O(l) ]

Question 32

weak acids partially dissociate, how is that shown?

Answer 32

through arrow going both ways (equilibrium arrow)

Question 33

What is Kw?

Answer 33

Ionic product of water - the ions in water H+ and OH- multiplied together

Question 34

equation for Kw?

Answer 34

Kw = [H+][OH-]

Question 35

in aqueous solution there will always be both H+ and OH- ions in solution. However, when there are more H+ ion, it is ...

Answer 35

acidic

Question 36

in an acid solution with pH 4, what is the concentration of OH- ions?

Answer 36

10 to the power of -10 because concentrations of H+ and OH- add up to -14 (kw value)

Question 37

How do you find the pH of a strong base?

Answer 37

use kw - find H+ concentration and ionic product of water value to find OH-

Question 38

How is finding the pH of a mono basic base and dibasic base different?

Answer 38

have to multiply number of OH+ ions by 2 because its a dibasic base so produces two moles of OH- ions

Question 39

when there are two acids in a reaction, How do you know which acids as a base or acid?

Answer 39

the strongest acid will act as the acid (bigger Ka value etc ) and other as the base