Nitrogen and Sulfur

Question 1

explain the lack of reactivity of nitrogen

Answer 1

N2 is non polar, no dipoles. triple covalent bond formed between two N atoms; this bond is very strong with high bond energy, needing a lot of energy to break it.

Question 2

describe and explain the basicity of ammonia. show the ionic equation that forms ammonium ion by an acid-base reaction.

Answer 2

it is a bronsted lowry base. Nitrogen’s lone pair can be donated to an H+ ion from an acid, forming a coordinate covalent bond. Ammonia is acting as a base in this reaction because it is accepting an H+ ion.
NH3(aq) + H+(aq) -> NH4+(aq)

Question 3

describe and explain the structure of the ammonium ion

Answer 3

ammonium ion has a tetrahedral shape with bond angle 109.5; it has 4 bond pairs 0 lone pairs.

Question 4

state the industrial importance of ammonia

Answer 4

as fertilizer usually injected into the soil,
reacted with acids to make solid ammonium salts e.g. NH3(aq) + HNO3(aq) -> NH4NO3(aq)
other uses are as a refrigerant gas, for purification of water supplies, and in the manufacture of plastics, explosives, textiles, pesticides, dyes and other chemicals

Question 5

state the industrial importance of nitrogen compounds derived from ammonia

Answer 5

ammonium nitrate pellets spread from tractors as fertilizers. to make explosives too.
ammonium sulfate and ammonium phosphate used in fertilisers.
concentrated nitric acid is also made from ammonia. it is also used to make many types of explosive such as TNT, manufacture of detergents, paints, pigments, dyes and nylon.

Question 6

state and explain the environmental consequences of the uncontrolled use of nitrate fertilizers

Answer 6

the water-soluble nitrates leach out of the soil by rain into groundwater into rivers and lakes promote an overgrowth of water plants, eutrophication (of algae on the surface). Light is blocked for other plant life in the water. When they and the algae die, bacteria feed decomposing them. Bacteria multiply rapidly with so much available food, using up dissolved O2 in the water. Fish die without dissolved O2 to be taken in through gills, the whole ecosystem is affected.

Question 7

describe and explain the displacement of ammonia from its salts. include, with state symbols, an example of the overall chemical equation and its ionic half-equation. What can this tell us?

Answer 7

ammonia is displaced from an ammonium salt when it is heated with a base
e.g.
*2NH4Cl(s) + Ca(OH)2(s) –heat–> CaCl2(s) + 2H2O (l) + 2NH3(g)
*(NH4)2SO4(s) + CaO(s) -heat–> CaSO4(s) + H2O(l) + 2NH3(g)
and
NH4+(s) + OH-(s) -> NH3(g) + H2O(l)
The reaction is used as the basis of the test for ammonium ions. A positive result will give off ammonia and as it is an alkaline gas, turns damp red litmus paper blue.

Question 8

state and explain the natural occurrence of oxides of nitrogen. use chemical equations to help.

Answer 8

N2(g) + O2(g) -> 2NO(g)
Here, lightning provides the activation energy needed for this reaction to occur.
2NO(g) + O2(g) -> 2NO2(g)
Here, the nitrogen(II) oxide is further oxidized by O2 in the air to give nitrogen(IV) oxide.

Question 9

state and explain the man-made occurrence of oxides of nitrogen. use chemical equations to help.

Answer 9

In a petrol (gasoline) engine, a spark is passed through a mixture of petrol vapor and air, to ignite the petrol. But it also causes some of the O2 and N2 in the air to combine.
N2(g) + O2(g) -> 2NO(g)

Question 10

State and explain the catalytic removal of oxides of N2 from the exhaust gases of internal combustion engines.

Answer 10

A catalytic converter, fitted in car exhaust systems, uses expensive metals like platinum coated on to a honeycomb structure to give a high surface area. Platinum catalyzes various reactions which help to get rid of pollutants from the exhaust gases.
In this case,
2NO(g) + 2CO(g) -> N2(g) + 2CO2(g)
The nitrogen oxides are reduced to harmless nitrogen gas which is released from the vehicle’s exhaust pipe.

Question 11

Explain why atmospheric oxides of nitrogen are pollutants, including their catalytic role in the oxidation of atmospheric sulfur dioxide.

Answer 11

Reactions for the catalytic activity of the nitrogen oxides:
SO2(g) + NO2(g) -> SO3(g) + NO(g)
then NO(g) + 1/2 O2(g) -> NO2(g)
2NO2 + H2O + 1/2 O2 -> 2HNO3
Nitrogen oxides cause acid rain, by the shown oxidation of SO2 in the atmosphere during acid rain formation as SO3 reacts with rainwater forming sulfuric acid. and it can also cause acid rain of hno3 as shown.
Nitrogen oxides also cause photochemical smog. It has a role in the formation of ozone, and of chemicals called peroxyacetyl nitrates (PAN). Ozone in smog is dangerous to health and so are peroxyacetyl nitrates. These last substances are formed by complex reactions involving nitrogen dioxide, unburnt hydrocarbons present in exhaust gases, and oxygen from the air.

Question 12

nitrous acid

Answer 12

HNO2

Question 13

ammonia production in factories

Answer 13

haber process
N2(g) + 3H2(g) ⇌ 2NH3(g)
deltaHr = -92 kJ mol-1
450 degrees Celsius, 200 atm, iron catalyst

Question 14

describe the formation of atmospheric so2 from the combustion of sulfur-contaminated fossil fuels

Answer 14

such as from combusting coal, crude oil, natural gas, petrol and diesel,
S + O2 -> SO2

Question 15

chem eq(s) role of so2 in the formation of acid rain

Answer 15

2SO2(g) + O2(g) -> 2SO3(g)
Oxides of nitrogen, such as NO2, as catalyst.

dissolves in, reacts with rainwater to make acid rain
SO3(g) + H2O(l) -> H2SO4(aq)

Question 16

describe the main environmental consequences of acid rain

Answer 16

On plants (especially trees growing at high altitudes, because they are more often in contact with the tiny droplets of h2so4 solution in clouds):

• leaches nutrients from soil, preventing healthy growth of plants.
• attack waxy layer on leaves, increasing water loss, making the plant more susceptible to disease and pests.

On rivers, streams and lakes and the fish and other animals in these habitats:
- lowers the pH of the water. Many aquatic animals are very sensitive to changes in pH and wont survive with the increase in acidity, like for instance insect larvae. —Other animals higher up the food chain may be more resistant, but their numbers will decrease as their food source dies off.

Buildings, statues and metal structures corrode and are damaged.

Question 17

fun fact: lead compounds actually stop the catalyst from working. You can’t use leaded petrol in a car with a catalytic converter.

Answer 17

oooo fun fun

Question 18

ammonium nitrate, ammonium sulfate
acidic or basic
respectively

Answer 18

acidic, acidic

Question 19

describe how no2 is produced by power stations (3)

Answer 19

high enough temperature to break strong triple bond in N2, then nitrogen and oxygen from the air react