Hello students in this module we are going to study the large scale manufacture of sulphuric acid using contact process as we can see on the screen is the setup for the plant of manufacturing of sulphuric acid which is used in the industries let’s study each and every part of the plant in detail first on the left hand side we have the blower we’re air is pumped inside the plant we also have the iron pyrite or sulphur burners where cipher or iron pyrites undergo the oxydation in the presence of air to form sulphur dioxide next the entire setup as we are going to see is for cleaning the sulphur dioxide so form sulphur dioxide is first put into the dusting tower where all the dust particles are settle down further it is sent through cooling pipes were sulphur dioxide is cooled after which it is taken to the scrubbing tower for further removal of dust particles and then to the dry tower to remove any amount of moisture which is present and finally to the arsenic purifier where arsenic oxide impurities are removed now where are all the impurities are removed or not can be tested using the small testing box clean and dry sulphur dioxide which is from its next sent to the contact tower now this student is the most important process of the entire plant where sulphur dioxide is getting converted to sulphur trioxide after the sulphur trioxide conversion it is taken into the absorption tower where it’s absorbed by concentrated sulphuric acid after absorption by sulphuric acid it is then finally diluted in the delusion tank for the concentration which is required this is the entire setup of the plant now let us begin with the main process that is the contact process now the main reaction which is happening over is the clean and dry gas mixture of sulphur dioxide and oxygen which is then passed through the contact tower that is so2 is reacting with o2 to form so3 now this reaction is not very feasible and hence we require a catalyst to increase the speed of the reaction the catalyst which is added is vanadium pentoxide again we can also use platinized asbestos as a catalyst but it is not prefer the reason is because when vanadium pentoxide is cheaper and it is less easy poisoned by impurities so even after all that purification and some amount of abilities are present they might poisonize platinized asbestos catalyst which is rare in case of vanadium pentoxide the promoter which is used over here now what is exactly a promoter the promoter is a substance which is added to a solid catalyst to improve its performance in a chemical reaction here the catalyst is increasing the speed of the reaction the promoter would further increase the speed of the reaction he promoter which is used here is potassium oxide along with vanadium pentoxide now this is the reaction which is happening between sulfur dioxide and oxygen let’s first study the first step where we are forming sulphur dioxide it is done in the first part of the first chamber of the entire process which is the blower and cipher or pyrite burner production of sulphur dioxide then in this chamber by bombing sulphur or iron pyrites now iron pyrites is FeS2 they burned in the presence of purified air now why do we use purified air because heat energy would be wasted in eating the unreacted nitrogen component of the raw air that is why we purify the air and then use it let’s see the first reaction which is occurring between sulfur and oxygen if you’re using cipher in this case so S+O2 gives us SO2 as we can see the reaction is self balance or alternatively we can use iron pyrites so let’s see the oxidation of iron pyrites which happens FeS2 which is iron pyrites reacts with oxygen to form fe2O3 + SO2 now this reaction is not balanced on the right hand side we can see oxygen odd to make it even will multiply fe2O3 by 2 now iron has become 4 on the right hand side whereas on the left hand side it is just one so on the left hand side will multiply FeS2 by 4 cipher on the left hand side thus become 8 and on the right hand side it is 1 so we’ll multiply SO2 on the right hand side by 8 total oxygen on the right hand side has become 22 now so left inside oxygen will be multiplied by 11 and hence we have the balanced chemical equation for fes2 + 11 or to giving to fe2O3 + 8SO2 and that’s our self or dioxide is produced which is going to get further purified