Sulfuric Acid

P Manufacture of paper

Di Manufacture of drugs

Di Manufacture of dyes has a ...

P Manufacture of pigments

H Household

D Detergent (manufacture ) in...

Beats As the electrolyte in car batteries

Per Petroleum refining

Minute Metallurgical processes

75% of the Sulfuric Acid that is produced is used to make fertilisers such as Superphosphate Ammonium

sulphate and Ammonium

phosphate.

Rock phosphate contains insoluble Calcium Phosphate. What is the formula for Calcium Phosphate???

Ca3(PO4)2

To be made available to plants it needs to be converted to a soluble form:

Ca3(PO4)2, (s) + 2H2SO4 (l) + 4H2O

Ca(H2PO4)2 (s) + 2CaSO4 • 2H2O (s)

Australia has substantial rock phosphate resources, especially in Queensland

Australian companies usually import rock phosphate from North Africa. WHY?

Cheaper

H2SO4 (l) + H2O (l) HSO4-(aq) + H3O+

(aq) The Ka for this reaction is very high

HSO4-(aq) + H2O (l) SO4

2-(aq) + H3O+

(aq) The Ka for this reaction is small

These reactions are EXTREMELY exothermic. Because of this it is important to add acid to the water and not the other way around.

The reaction is so exothermic that water becomes steam and causes the solution to splutter, causing serious injury.  

Sulphuric acid acts as a catalyst in the following reactions:

C1 2H22O11 (s) (with H2SO4) 12C (s) + 11H2O (l)

Is this a condensation reaction, hydrolysis reaction or neither?

CuSO4 • 5H2O (s) CuSO4 (s) + 5H2O(l)

  Sulphuric acid can even be used as a

dehydrating agent for gases by bubbling them through the sulphuric acid. However, these gases cannot be bases

(i.e. NH4) or reductants. Why?

What health implication might there be for sulphuric acid being such a strong dehydrating agent?

If sulfuric acid is spilt on the skin, wash with running water (wink wink, hint hint)

If there is a large amount of sulfuric acid, first wipe it off quickly

A very strong oxidant, especially when hot.

H2SO4 can be reduced to SO2 S or H2S :

Zn (s) + 2H2SO4 (l) ZnSO4 (aq) + H2O (l) + SO2 (g)

3Zn (s) + 4H2SO4 (l) 3ZnSO4 (aq) + 4H2O (l) + S (s)

4Zn (s) + 5H2SO4 (l) 4ZnSO4 (aq) + 4H2O (l) + H2S (g)  However, when zinc reacts with dilute H2SO4:

Zn (s) + H2SO4 (l) ZnSO4 (aq) + H2 (g)

For each of the reactions above, identify the oxidation numbers of Sulfur.

The production of H2SO4 usually follows the following process:

S SO2 SO3 H2SO4

This is know as “The Contact Process”

Combustion of sulphur recovered from natural gas and crude oil

SO2 formed during the smelting of sulphuric ores of Cu, Zn or Pb

It can be mined directly. This is not necessary in Australia

If solid sulfur is the starting point it is made molten and then sprayed under pressure into a furnace.

It will then combust in air to produce SO2

The high surface area of molten S results in a very fast combustion reaction.

S(l) + O2(g) SO2 (g) Δ H = -297 kj mol-1

Temperature may reach 1000°C so SO2 needs to be cooled

SO2 is converted to SO3 with the use of the V2O5 catalyst.

2SO2 (g) + O2(g) (with V2O5 ) 2SO3 (g) Δ H =

-197 kj mol-1

Where does this reaction occur? Well, thanks for asking, it occurs in a .....

SO2 is mixed with air and passed through trays containing loosely packed porous pellets of the catalyst V2O5

Because the reaction is so exothermic it must continually be cooled

The temperature in the converter is maintained at 400 - 500°C and a pressure of 1 atmosphere

Nearly complete conversion from sulphur dioxide to sulphur trioxide is achieved. SO?

Use Le Chatelier’s principle to determine what temperatures and pressure is desired for this reaction.

Also, would excess reactants be employed?

Excess products? Why/Why not?

What about dilution?

Temperature: Because the reaction is exothermic Le Chatalier predicts the reaction will become more product favoured when the temperature is decreased

Because the generation of products decreases pressure, an increase in pressure will push the reaction forward

By supplying excess reactants the system will try to re-establish equilibrium by getting rid of those reactants. This will also push the reaction forward.

What factors will increase the rate of reaction?

High Temperature

High Pressure

The use of a catalyst

In most instances both a product favoured reaction and a speedy reaction desire the same factors.

Excess oxygen is used as the excess reactant

  Even though increased pressure increases

the rate of reaction and pushes it forwards, manufacturers do not bother as high yields are achieved without this costly addition.

Le Chatelier dictates that a low temperature will push the reaction forward. However, the rate of reaction will slow with reduced temperature. What to do?!

Luckily, the catalyst saves the day by making lower temperatures viable.

The effect of the catalyst is maximised by spreading it over trays which increases the surface area.

The catalyst can become ‘poisoned’ and rendered ineffective by dust. Therefore the air and sulphur dioxide pass through electrostatic precipitators before they enter the converter.

Absorption of SO3

SO3 (g) + H2O (l) H2SO4 (aq) Δ H = -130 kj mol-1

Direct reaction with water is very exothermic which results in the formation of steam. Sulfuric acid as a gas is very difficult to collect so an absorption tower is used instead:

H2SO4 (aq) + SO3 (g) H2S2O7 (l) This product is called oleum

Very little reactant is left. Oleum is then mixed with water:

H2S2O7 (l) + H2O (l) 2H2SO4 (l)

Sometimes the reactions occur simultaneously: H2SO4 (aq) + SO3 (g) + H2O (l) 2H2SO4 (l)

Plants built after 1970 use ‘double desorption’ processes. The unreacted SO2 is passed back through the catalytic converter. This increases efficiency from 98% to 99.6%

SO2, SO3 and H2SO4 emissions are continuously monitored.

H2SO4 mist is minimised by controlling the operating temperature of the absorber, gas flow rates and concentrations.

H2SO4 has a high boiling temperature of 290°C and a low vapour pressure. There is no appreciable air pollution problem with its storage, handling and shipping.

Cooling water is usually recycled

Improvements to conversion have occurred by adding small amounts of cesium to the V2O5 catalyst. This has increased efficiency and allows the reaction to

occur at even lower temperatures. Unfortunately the presence of cesium increases the cost of

the catalyst by three times.

Spent Vanadium is slightly toxic so it needs to be recovered from ‘poisoned’ catalyst before the catalyst is disposed of in landfill.

“The ‘Contact Process’ actually reduces pollution!”

Prove or disprove this statement.

2 minutes 2 reasons

By using the sulphur by products of other reactions it prevents these pollutants escaping into the atmosphere. This helps to prevent acid rain.

Yay!

More energy is produced in the process than is used by it. Another yay!

This energy is recycled by the plant and can even be sold to other plants for use in chemical manufacture.

Sometimes the energy is used to produce ‘green’ electricity.

Transport procedures need to be in place for loading and unloading

H2SO4 is highly corrosive. It is a strong dehydrating agent. It can burn eyes and skin severely. It can cause blindness and 3rd degree burns.

Sulfuric acid mist can cause problems such as pulmonary oedema (fluid in the lungs).

Sulphur dioxide and sulphur trioxide are respiratory irritants, damage plants and contribute to acid rain.

Oleum is a highly corrosive, oily liquid, that produces SO3 fumes. These fumes can build up and accidental release procedures need to be in place.

Work areas must be well ventilated and employees must wear protective clothing.

Acid spills are contained using materials such as earth, clay or sand, then slowly diluted with water before being neutralised with a base (usually CaCO3 or Na2CO3)

What does “P DiDi has a PhD in Beats Per Minute” stand for?

What is the name, location of and formula for the catalyst that is used?

Vanadium Pentoxide, Converter, V2O5 What is the chemical formula for Oleum? H2S2O7

Which reaction occurs in the ‘converter’? SO2 to SO3

What two reactions need to occur for the adsorption of sulfur trioxide?

SO3 + H2SO4 H2S2O7 H2S2O7 + H2O 2H2SO4 How is sulfur converted to sulfur dioxide? Molten sulfur is sprayed into the air Write the formula for the production of superphosphate

http://www.youtube.com/watch?v=zTLiJE-j1-I

From Chapter 22 Answer: Q 2, 3, 5, 6, 7, 8, 9, 10, 11, 13, 15

You will have a SACT test on sulfuric acid and its production next Monday, so get studying!