Nitrogen and sulfur

Ammonia is made in the Haber process.

a. What is the formula of ammonia?

b. Write a balanced equation for the formation of ammonia from nitrogen and hydrogen in the Haber process.

c. Give three uses of ammonia.

a. The formula of ammonia is NH₃

b. The balanced equation for the formation of ammonia from nitrogen and hydrogen in the Haber process

`N_2 + 3H_2 ⇌ 2NH_3`

c. Three uses of ammonia 

(1) to make ammonium salts in neutralisation reactions with different acids

(2) agriculture as fertilizer

(3) a refrigerant gas, for purification of water supplies

a. Give the formulae of the following ammonium salts:

i. ammonium chloride

ii. ammonium nitrate

iii. ammonium sulfate

b. Ammonium chloride reacts with calcium hydroxide when heated to produce ammonia gas.

i. Is this reaction carried out using solids or solutions?

ii. Write the balanced equation for this reaction.

a. The formulae of the following ammonium salts

i. NH₄Cl

ii. NH₄NO₃

iii. (NH₄)₂SO₄

b. 

i. This reaction is carried out using solid

ii. `2NH _4Cl + Ca(OH)_2 → CaCl_2 + 2H_2O + 2NH_3`

The reaction `2SO _2(g) + O_2(g) ⇌ 2SO_3(g)`

reaches dynamic equilibrium. The forward reaction is exothermic. The reaction is catalysed by vanadium(V) oxide, V₂O₅. You are given a vessel containing all three gases at equilibrium.

What will happen to the position of equilibrium if:

A. you add more oxygen to the vessel?

B. you remove some sulfur trioxide from the vessel?

C. the pressure in the vessel is lowered?

D. more V₂O₅ is added?

E. the temperature in the vessel is increased?

A. When we add more oxygen meaning that the concentration of oxygen will increase, making this reaction shift to the right

B. When we remove some sulfur trioxide meaning that the concentration of sulfur trioxide decrease, making this reaction shift to the right

C. The forward reaction is exothermic, pressure in the vessel is lowered, leading to this reaction shifting to the left

D. When we add more catalysts, they do not affect the reaction equilibrium. They help a reaction to reach at equilibrium faster

E. The forward reaction is exothermic, the temperature in the vessel is increased, leading to this reaction shifting to the left.

A. Give three uses of sulfuric acid.

B. Why is it important that as little sulfur dioxide as possible is released into the atmosphere when sulfuric acid is manufactured?

C. Explain, including a balanced equation, how sulfur dioxide enters the atmosphere from a coal-fired power station.

A. Three uses of sulfuric acid 

(1) Fertilisers

(2) Pigments

(3) Cleaning metal surfaces

B. Because it can cause acid rain

C. Because there are sulfur impurities in coal, and they can react with oxygen with the heat presence.

`S + O_2 -> SO_2`

Extreme conditions are required to synthesise ammonia from nitrogen in the Haber process due to the lack of reactivity of the nitrogen molecule. 

Give two reasons for the lack of reactivity of the nitrogen molecule, N₂.

The reasons for the lack of reactivity of N₂ are

(1) The strong triple bond in a molecule

(2) N₂ is a non-polar molecule

Under conditions of high temperature, nitrogen and oxygen react together to give oxides of nitrogen.

A. Write an equation for a possible reaction between nitrogen and oxygen.

B. State two situations, one natural and one as a result of human activities, in which nitrogen and oxygen react together.

C. State the two main environmental effects of the presence of nitrogen oxides in the atmosphere.

A. The equation for a possible reaction between nitrogen and oxygen

`N_2 + 2O_2 -> 2NO_2`

B. One natural as a result in which nitrogen and oxygen react together is lightning

One as a result of human activities is combustion of fuels

C. Two main environmental effects of the presence of nitrogen oxides in the atmosphere are photochemical smog generation and acid rain production

A. State how nitrogen monoxide is removed from the exhaust gases of motor vehicles.

B. Write an equation for this process.

A. Nitrogen monoxide is removed from the exhaust gases of motor vehicles by a catalytic converter or passing the exhaust gases over hot catalysts, for example, Pt or Rh

B. An equation for this process

`2NO + 2CO -> N_2 + 2CO_2`

Nitrogen oxides can react with substances in the air to make secondary pollutants. 

One of these secondary pollutants is peroxyacetyl nitrate, commonly known as PAN.

A. State the type of compounds that react with nitrogen oxides to form PAN.

B. PAN is one of the components found in photochemical smog. Explain why the term photochemical is used to describe smog.

A. The type of compounds that react with nitrogen oxides to form PAN are unburnt hydrocarbons or volatile organic compounds

B. The term photochemical is used to describe smog because the reaction (between nitrogen oxides and unburned hydrocarbons/VOCs) is initiated by the energy from sunshine.

Using your knowledge of the Bronsted-Lowry theory, which of the following correctly describes ammonia?

A. Neutral

B. Acid

C. Base

D. Amphoteric

The answer is C

The Bronsted-Lowry theory describes acids as proton donors and bases as proton acceptors.

Thus,

`NH_3 + H_2O -> NH""_4^(+) + OH^-`

A is incorrect because NH3 is not neutral

B is incorrect because NH3 cannot donate a proton

D is incorrect because it does not act as an acid

Which statement correctly describes an ammonium ion, `NH""_4^(+)`?

A. The bonds are all the same length.

B. All bond angles are 107°

C. Ammonium ions are unreactive when heated with NaOH (aq).

D. Ammonium ions are formed when ammonia behaves as an acid.

The answer is A

Because the distance between the two nuclei of each bond is the same and the difference in electronegativity and bond strength is the same in all for N-H bonds 

B is incorrect because this ion has a tetrahedral shape which has angle of 109.5

C is incorrect because `NH""_4^(+) + OH^-) -> NH_3 + H_2O`

D is incorrect because ammonia cannot behave as an acid