Studied by 22 people
What is a Bronsted-Lowry acid
A species which donates H+ in a reaction
What is a Bronsted-Lowry base
A species which accepts H+ in a reaction
What are conjugate acid-base pairs
Acids react to form bases
Bases react to form acids
What does amphiprotic mean
According to the Bronsted-Lowry theory it is when a substance posses both a lone pair of electrons and a H+ which can be donated. Meaning it can act as a base or acid.
What does the reaction between an acid and a metal form
Salt and Hydrogen
What does the reaction between an acid and a base form
Salt and Water
What does the reaction between an acid and carbonate form
Salt, water and carbon dioxide
What is the equivalence point in an acid-base titration
Where the acid and the base exactly neutralise each other
How can we calculate the concentration of H+ from pH
[H+] = 10-pH
How does the increase by 1 unit in pH affect the concentration
It decreases concentration 10 times
How do we calculate pH from [H+]
pH = -log[H+]
What is Kw
The ionic product constant of water
It is equal to 1 Ă— 10-14
How can Kw show us the pH of pure water
[H+] = the square root of Kw
Then -log[H+] gives pH which in pure water is 7
What is the relation ship between [H+] [OH-] and Kw
[H+] = Kw/ [OH-]
[OH-] = Kw/[H+]
What is the difference between a weak and strong acid
Strong acids fully dissociate in water to form ions in solution
Weak acids only partially dissociate in a reversible reaction
Whats the difference between a strong base and a weak base
A strong base will ionise fully
A weak base will only ionise partially
What do the conjugate bases show about strength
A strong base will have a conjugate pair of a weak acid
A strong acid will have a conjugate pair of a weak base
What are examples of strong acids
HCl = Hydrochloric acid
HNO3 = Nitric acid
H2SO4 = Sulphuric acid
What are examples of weak acids
Any organic acid
H2CO3 = Carbonic acid
H3PO4 = Phosphoric acid
What are examples of strong bases
LiOH = Lithium hydroxide
NaOH = Sodium hydroxide
KOH = Potassium hydroxide
Ba(OH)2 = Barium hydroxide
What are examples of weak bases
NH3 = Ammonia
All amine bases
How does electrical conductivity differ with strength of base/acid
Stronger acids/bases show higher electrical conductivity due to more mobile ions
What is the difference between lewis acids and bases
A lewis acid is an electron pair acceptor
A lewis base is an electron pair donor
What is a nucleophile
an electron rich species which donates a lone pair to form a new covalent bond in a reaction.
It is a lewis base.
What is an electrophile
An electron deficient species which accepts a lone pair from another reactant to form a new covalent bond.
It is a lewis acid
How do the bronstead and lowry, and lewis theories of acids and bases compare
Bronstead and lowry focuses on proton donation/acceptance whereas lewis focuses on electron pairs
All Bronstead and lowry acids are lewis acids but not all lewis acids are Bronstead and lowry acids
How does a shift in equilibrium alter the Kw
Equilibrium shifted to the right increases Kw
Equilibrium shifted to the left decreases Kw
What is the pOH scale
The parallel scale
Used to describe the concentration of OH- ions in a solution.
How is pOH calculated
-log [OH-] = pOH
[OH-] = 10-pOH
How can pKw be calculated
pH + pOH = pKw
How is pH and pOH of strong acids/bases calculated
Assuming full dissociation so from equilibrium concentrations
What is Ka and how is it calculated
Ka is the acid dissociation constant
It is calculated by dividing product concentrations by reactant concentrations
The higher the Ka the stronger the acid.
Ka can also be calculated from pKa
What is Kb and how is it calculated
The base dissociation constant
It is calculated by dividing product concentrations by reactant concentrations
The higher the Kb the stronger the base
What happens when Ka or Kb is very low
Barely any dissociation/ionisation occurs so the concentration at equlibrium is around the same as the initial
What is pKa and pKb
The negative logarithm of Ka and Kb
They are usually positive and have no units
Low pKa/pKb means a strong acid/base its the opposite to Ka/Kb
What is a buffer solution
It is resistant to changes in pH on the addition of small amounts of acid/alkali
How is an acidic buffer created
Mixing an aqueous solution of a weak acid with a solution of its salt of a strong alkali.
How is a basic buffer created
Mixing an aqueous solution of a weak base with a solution of its salt of a strong acid.
How does dilution affect a buffer solution
Diluting a buffer does not change its pH
However it decreases its buffering capacity
What does the pH at the half equivalence point show us
pH = pKa
What are indicators
they are weak acids/bases in which the dissociated and undissociated forms have different colours
What indicators are used for strong acid + strong base
Phenolphthalein
Methyl orange
What indicators are used for weak acid + strong base
Phenolphthalein
Phenol red
What indicators are used for strong acid + weak base
Methyl orange
Bromophenol blue
How is acid rain formed
Dissolved carbon dioxide in water forms a weak carbonic acid which gives the water a minimum pH of 5.6. However with additional pollutants it forms acid rain. The main pollutants are sulfur and nitrogen which forms acid rain when they dissolve.
What is acid deposition
Broader than acid rain and contains all processes by which acid components as precipitates or gases leave the atmosphere.
What is wet acid deposition
Rain, snow, sleet, fog, mist, dew
Aqueous precipitates.
What is dry acid deposition
acidifying particles, gases falling to the ground as dust/smoke later dissolve in water to form acids
How is sulfur oxide released into the atmosphere.
The burning of fossil fuels, particularly coal and oil
Also in the industrial process of smelting where metals are extracted from their ores
Which acids are formed from sulfur oxide
It dissolves in water to form sulfurous acid
It is oxidised to sulfur trioxide which then dissolves in water to make sulfuric acid
How is nitrogen monoxide released into the atmosphere
Mainly from internal combustion engines, burning of the fuel releases heat energy that causes nitrogen and oxygen from the air to combine
What are the environmental effects of acid deposition
Causes slower growth, injury or death of plant life
Causes soil leaching where important minerals in the soil become soluble and wash away, leaving the plants deficient.
It can make lakes “dead” meaning unable to support life. Many fish cannot survive below pH 5
What are the human/social impacts of acid deposition
Fine sulphate and nitrate particles can be inhaled and irritate the respiratory tract and also can cause irritation to the eyes.
Marble and limestone react with the acid rain, forming a calcium salt which is more soluble making it easier to wash away and degrade. Leading to erosion of buildings.
It can also increase the rate of rusting
how can we reduce nitrogen oxide emissions
Catalytic converters in vehicles to control exhaust gases.
Lower temperature combustion in vehicles
How can we reduce sulfur dioxide emissions
Hydrodesulfurization (HDS) is a catalytic process that removes sulfur from refined petroleum products by reacting it with hydrogen to form hydrogen sulfide
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