Question

In Siemens ozoniser, 60% ${{O}_{2}}$is converted to ozone. How many moles of ozone will be obtained from 10 moles of ${{O}_{2}}$?

Answer 1

Hint: We carry out the process of conversion of oxygen to ozone in an ozoniser. By finding the number of moles of oxygen converting to ozone and balancing the stoichiometry, we can find out the number of moles of ozone formed.

Complete answer:
When we pass an electric current through pure, cold and dry molecular oxygen in a specially designed device, we obtain ozone which is a triatomic compound of oxygen.
One such device was designed by Siemen, known as the Siemens ozoniser. In this device, two co-axial glass tubes are fused together and we use a layer of tin foil to coat the extreme inner and the outer sides of the tube. Then, we connect the tin coatings to the terminals of an induction coil which passes high voltage current through the space. After that we introduce pure and cold oxygen to the space through which we pass a silent electrical discharge without sparking. This gives us ozonised oxygen which contains around 10% - 15% ozone.
In the given question, we have a Siemens ozoniser which converts 60% of di-oxygen to ozone. We have to find out the number of moles of ozone prepared by 10 moles of di-oxygen. We can write that-
Number of moles of 10 moles ${{O}_{2}}$ converted to ozone = 60% of the 10 moles = $\dfrac{60}{100}\times 10=6\text{ moles}$ i.e. 6 moles of di-atomic oxygen were converted to ozone. We can write the balanced equation as-
     \[6{{\text{O}}_{2}}\to 4{{O}_{3}}\]
As 6 moles of oxygen was converted to ozone therefore we balanced the equation by multiplying the right hand side by 4 which gave us that 4 moles of ozone was prepared.
Therefore, 4 moles of ozone was obtained from 10moles of ${{O}_{2}}$in Siemens ozoniser.

Note: In a Siemens ozoniser, the yield of ozone wasn’t that great but there are a few precautions we can take for a better yield like use of pure and dry oxygen, making sure that the ozoniser is completely dry, maintaining a low temperature of zero degree Celsius and making sure that there is no sparking. There are other ozonisers too like Brodie’s ozoniser and Siemen-Halske’s ozoniser.