Ammonia and sulfuric acid validation

12 Principles of green chemistry

Prevent waste

Maximise atom economy

less hazardous chemical synthesis

safer chemicals and products

safer solvents and reaction conditions

increase energy efficiency

use renewable raw materials

avoid chemical derivatives

use catalysts, not excess reactants

design chemicals and products to be bio-degradable

analyse in real time to prevent pollution

minimize potential accidents

percentage yield equation

(actual yield/theoretical yield) x 100

how is theoretical yield found

mass of products if 100% conversion of reactants to products

what is ammonia mostly used in

ammonia salts, used in fertilizers

Haber process reaction

N2+3H2 <---> 2NH3 △H=-92 KJ Mol-1

How is hydrogen collected for Haber process

"steam reforming"

CH4+H2O <---> CO + 3H2

CO + H2O <---> CO2 + H2

effects of pressure and temp increase on Haber process and Sulfur dioxide to sulfur trioxide

Increased pressure, increased yield and reaction rate

Increased temp, decreased yield but increased reaction rate

Haber Process conditions

350-500 C

100-250 atmospheres

Iron/iron oxide (Fe3O4) catalyst

yield of Haber process

20% at each pass in reactor, ultimate yield of 98%

Use of sulfuric acid

used to dehydrate, extracts hydrogen and oxygen from sugar in the form of water

also as a catalyst or as a strong acid

Contact process main steps

1. Sourcing SO2

2. Sulfur dioxide to Sulfur trioxide

3. absorption of Sulfur trioxide to sulfuric acid

Sourcing SO2 steps

From natural gas or crude oil

S + O2 ---> SO2 △H=-297 KJ mol-1

Dried air mixed with molten sulfur produces sulfur dioxide

Sulfur dioxide to sulfur trioxide steps

2SO2 + O2 <---> 2SO3 △H=-197 KJ mol-1

Sulfur dioxide to sulfur trioxide conditions

Vanadium oxide (V2O5) catalyst

400-500 C

1 atmosphere (cost of maintaining high pressure outweighs benefits)

Steps of absorption of Sulfur trioxide to sulfuric acid

1. Sulfur trioxide dissolves into acid called Oleum

SO3 + H2SO4 ---> H2S2O7

2. Oleum mixed with water to produce sulfuric acid

H2S2O7 + H2O ---> 2H2SO4

Effects or Sulfur dioxide pollution

Corrosion of metals,

acid rain, sulfur dioxide reacts with rainwater to form sulfurous acid

How is sulfur dioxide pollution limited

Double absorption, where unreacted SO2 is recollected

increases sulfur dioxide conversion from 98% to 99.6%