8.. Flashcards

Question

weak bases

Answer 1

base that partially (or incompletely) dissociates in aqueous solutions - NH3 (ammonia), amines and some hydroxides of transition metals - equilibrium

Answer 2

- pH values - electrical conductivity - reactivity

Answer 3

- strong acids have a higher concentration of H+, so they conduct electricity better -

Answer 4

- strong and weak acids of the same concentrations react differently with reactive metals - this is bc the concentration of H+ is greater in strong acids compared to weak acids - The greater H+ concentration means that more H2 gas is produced in a shorter time -

Answer 5

- Rain is naturally acidic because of dissolved CO2 which forms carbonic acid H2O (l) + CO2 (g) ⇌ H2CO3 (aq) - Carbonic acid is a weak acid and dissociates in the following equilibrium reaction giving a pH of 5.6 H2CO3 (aq) ⇌ H+ (aq) + HCO3- (aq) For that reason acid rain is defined as rain with a pH of below 5.6 Acid deposition includes all processes by which acidic components leave the atmosphere - This could be gases or precipitates There are two types of deposition: wet acid deposition and dry acid deposition - Wet acid deposition refers to rain, snow, sleet, hail, fog, mist and dew - Dry acid deposition refers to acidic particles and gases that fall to the ground as dust and smoke - Acid deposition is formed when nitrogen or sulfur oxides dissolve in water to form HNO3, HNO2, H2SO4 and H2SO3

Answer 6

- fossil fuels are often contaminated with small amounts of sulfur impurities - when these contaminated fossil fuels are combusted, the sulfur in the fuels get oxidised to sulfur dioxide - sulfur dioxide may be further oxidised to sulfur trioxide - the sulfur dioxide and trioxide then dissolve in rainwater droplets to form sulfurous acid (H2CO3) and sulfuric acid (H2CO3) - these acids are components of acid rain which has several damaging impacts on the environment

Answer 7

- the temperature in an internal combustion engine can reach 2000 °C - nitrogen and oxygen, which at normal temperatures don't react, comine to form nitrogen monoxide - nitrogen monoxide reacts further forming nitrogen dioxide - nitrogen dioxide gas rects with rain water to form a mixture if nitrous and nitric acids, which contribute to acid rain - lightning can also trigger the formation of nitrogen monoxide and nitrogen dioxide in the air - -

Answer 8

- acid deposition can react with metals and rocks (limestone) causing buildings and statues to get damaged - limestone and marble both contain CaCO3 - calcium carbonate reacts with sulfuric or nitric acids causing stoneworks to corrode or weaken - metallic structures, such as iron bridges, are vulnurable to corrosion by wet and dry deposition forming the salt of the metal

Answer 9

- Apart from acid deposition directly falling on leaves and killing plants, acid particulates can block stomata ( plant pores) and prevent gaseous exchange - Acid rain can fall on soils and release important minerals such as magnesium, calcium and potassium which are leached (washed out) from soils and are therefore unavailable to plants - Aluminium ions released from rocks are toxic to many plants and damage their roots

Answer 10

- When acid rain falls on rivers and lakes the pH can fall to levels that are unable to support life - Below about pH 4, aluminium ions are released from rocks when they are held as aluminium hydroxide - Alumnium ions are toxic to fish as they damage the gills and prevent fish from efficiently absorbing oxygen - Nitrate ions from nitric acid in acid rain can contibute to over-fertilization of waterways and lead to eutrophication - Eutrophication is excessive algal growth that results in oxygen depletion and stagnation of waterways

Answer 11

- no direct impact on skin - however, acid particulates in the air can increase the risk of respiratory diseases - When acid rain comes into contact with metal pipes there is an increased risk that toxic metal ions will be released into the water supply such as Cu2+, Al3+ and Pb2

Answer 12

- removal of sulfur from fossil fuels can either take place pre-combustion or post-combustion - SO2 and SO3 are both acidic and toxic - sulfur dioxide is produces naturally during volcanic eruptions - large quantities have been emitted by burning coal, oil and natural gas

Answer 13

- Pre-combustion takes place for coal and petroleum, altough it is expensive to remove all the sulfur, so a small percentage often remains - essential to remove most of the sulfur as it damamges the workings of the internal combustion engines - sulfur is removed by reacting it with hydrogen - hydrodesulfurization - sulfur is recovered and used in the manifacture of sulfuric acid

Answer 14

- carried out in a coal fired power stations - the waste gases from burning the coal contain sulfur dioxide - the waste gases are passed through a wet slurry of calcium oxide and calcium carbonate which react with SO2 and produce calcium sulfate - calcium sulfate is also known as gypsum and is used to make plsterboard and other useful building materials

8.. Flashcards

(40 cards)