UNIT 8 - Acids And Bases Flashcards
State the equation of pKw
pH + pOH
State how is SO2 most usually produced and its environmental consequences.
- Produced from the burning of fossil fuels especially coal and heavy oil in power plants used to generate electricity.
- Dissolved in water to form sulphurous acid or can be oxidized to suffer trioxide which then dissolves in water to form sulphuric acid.
State the ways of reduction of SO2 emissions.
- pre-combustion methods - reducing the super present in coal or oil before combustion.
- post-combustion methods - flue-gas desulfurisation
State how is NO most usually produced and its environmental consequences.
- mainly from internal combustion engines where the burning of fuel releases heat energy causing nitrogen and oxygen from the air to combine.
- nitrogen dioxide is formed from the oxidation of nitrogen monoxide and NO2 will dissolve in water to form a mixture of nitrous acid and nitric acid.
Define hydrodesulfuristation.
Catalytic process of removing soulful from refined petroleum products by reacting it with hydrogen sulphide, a highly toxic gas which is captured and later converted into elemental soulful for use in the manufacture of sulphuric acid.
Define flue-gas desulphurisation.
Removal of up to 90% of SO2 from flue gas in the smoke of coal-fired power station before it is released into the atmosphere through reacting wet slurry of CaO and CaCO3 with SO2 to form the neutral product calcium sulphate CaSO4.
Describe the ways of reducing NO emissions.
- Catalytic converters in vehicles - controlling of the exhaust gases with the use of catalytic converters where the hot gases are mixed with air and passed over a platinum or palladium based catalyst which converts them into relatively harmless products.
- Lower temperature combustion - the formation of nitrogen monoxide at lower temperature.
State the factors determining the pH of a buffer.
- pKa / pKb of its acid/base
- ratio of its initial concentrations of acid and salt/base and salt.
List the 3 main types of reaction by which acids react to form salts.
- Acid + reactive metal -> salt + hydrogen
- Acid + base -> salt + water
- Acid + carbonate -> salt + water + carbon dioxide
Define alkalis.
Bases that dissolve in water to form the hydroxide ion OH- (subgroup of bases).
Define leaching.
Important minerals for the soil such as Mg2+ , Ca2+ and K+ become soluble and so wash away before they can be absorbed by plants.
State what are the pKa / pKb values dependant on and its consequence.
Temperature and thus they need to be quotes at a specific temperature.
List the only soluble hydroxides.
- NH4OH
- LiOH
- NaOH
- KOH
State the pH at half equivalence point.
pH = pKa
pOH = pKb
List the only soluble hydrogencarbonates.
- NaHCO3
- KHCO3
- Ca(HCO3)2
State the effect of temperature on the value of Kw and equilibrium.
- it will shift to the right
- increase in the Kw value (thus decrease in pH and a reduction in temperature)
Define Ka and list an expression for it.
Acid dissociation constant/acid ionization constant is a direct measure of the strength of an acid as it depends on the position of the equilibrium of acid dissociation.
Ka = ([H3O+][A-]) /[HA]
State the condition necessary for the indicator to be effective in singling the equivalence point of a titration.
End-point coincides with the pH are equivalence point.
List the weak acids.
- CH3COOH
- H2CO3
- H2PO4
State the formulas for pKa and pKb.
pKa = -log 10 Ka
pKb = -log 10 kb
State the formula for Kw.
Kw = [H+][OH-]
List the only soluble carbonates.
- (NH4)2CO3
- Na2CO3
- K2CO3
Describe the impact of acid deposition on human health.
- Asthma
- Bronchitis
- Emphysema
- Irritation of the eyes
State the Brønsted-Lowry-Lowry theory.
- acid is a proton (H+) donor
- base is a proton (H+) acceptor
State the main components of acid rain.
- H2SO3
- H2SO4
- HN02
- HNO3
Distinguish through definition strong and weak acids and bases.
- strong acids and bases ionize almost completely in a solution
- weak acids and bases ionize only partially in a solution (the reaction is reversible)
State where does the point of inflection occur on the pH curve and how is it related to the equivalence point.
- at equivalence a big jump in pH occurs
- equivalence point is half-way up this jump
State the formula for concentration of protons based on the pH.
[H+] = 10 -pH