Mass transfer and examples of mass transfer processes

This ppt contain introduction to mass transfer and examples of process.

1. Mass Transfer and Examples of Mass Transfer Processes Presenter: Muhammad Shams Roll No:D-19F-CH-02 Instructor: Ma’am Amna Anjum

2. The operation carried out for separating the component of the mixture, involving the transfer of (mass) material from one homogeneous phase to another, due to the difference in vapor pressure, solubility or diffusivity and in which driving force for transfer is a concentration the difference is called mass transfer operations. Example:- Distillation, Gas absorption, Liquid Extraction, Drying Mass Transfer

3. Mass transfer may occur in a gas mixture, a liquid solution or solid. Mass transfer occurs whenever there is a gradient in the concentration of a species. The basic mechanisms are the same whether the phase is a gas, liquid, or solid.

4. Concentration Number of molecules of each species present per unit volume ( ) Molar concentration of species i = Number of moles of i per unit volume ( ) Mass concentration = Mass of i per unit volume ( )  

5. Whenever there is concentration difference in a medium, nature tends to equalize things by forcing a flow from the high to the low concentration region . The molecular transport process of mass is characterized by the general equation :  

6. Examples Of Mass Transfer Processes

7. Gas to Gas Mass Transfer When we light an incense stick in a corner of our room, its smell spread in the whole room quickly. The smell of perfume spreads due to diffusion of perfume vapors into air. Same happens when we opens a bottle of perfume.

8. 2. Liquid to Gas Mass Transfer Diffusion: A cup of water left in a room eventually evaporate as a result water molecules diffusing into the air. This is liquid to gas diffusion. Gas absorption : If a mixture of ammonia and air is contacted with liquid water, a large portion of ammonia will dissolve in the liquid, and in this way air ammonia mixture can be separated . Humidification of the air: When dry air contacted with liquid water result in evaporation of some water into the air.

9. 3. Liquid to Liquid Mass Transfer The spreading of blue color of copper sulphate into water, on its own, is due to the diffusion of copper sulphate particles and water . Acetone water solution is shaken in separating funnel with carbon-tetra chloride and the liquid allowed to settle, a large portion of acetone will be found in the carbon chloride-rich phase and will thus have been separated from the water.

10. A piece of solid (dry ice) also gets smaller and smaller in time as the molecules diffuse into the air.   4 . Solid to Gas Mass Transfer

11. 6 . Gas to Liquid Mass Transfer Small fraction of in the air diffuses into the water and meets the oxygen needs of marine animals If air is brought into contact with an ammonia-water solution, some of the ammonia leaves the liquid and enters the gas phase.   Leaching of gold from its ore by cyanide solutions. Another example is the leaching of cotton seed oil from the seeds by hexane. Spoon of sugar in a cup of coffee. 5. Solid to Liquid Mass Transfer

12. 7. Solid to Solid M ass T ransfer If metallic gold and metallic lead blocks are bound together tightly and kept undisturbed for a long time then the particles of gold are found to have diffused into lead or vise versa, but this is very slow diffusion . If we write something on black board and don't erase it after some time of period it becomes difficult to erase it because particles of chalk have diffused into board. GOLD LEAD

13. Thank You References: https://chemicalada.blogspot.com/2015/11/examples-of-mass-transfer.html?m=1 https://www.slideserve.com/megan-downs/introduction-to-mass-transfer https://www.knowledgeuniverseonline.com/ntse/Chemistry/diffusion-in-solid-liquid-gases.php