How Concentration Affects Electrolysis Product

When the electrolyte is concentrated, the products of electrolysis can be affected. This applies to concentrated ions with small electrode potential difference between the species to be discharged at the electrode. Let's use the electrolysis of brine or concentrated NaCl as an example. 1. Reduction at Cathode Species migrating to cathode will be Na+ and water. Since reduction occurs at the cathode, we need to find both species on the left hand side of half equation in the Data Booklet. The E value for Na+ is much more negative than E value for H2O. This means it's much harder to reduce Na+ as compared to water, even if Na+ is concentrated. Hence water will be reduced at the cathode. 2. Oxidation at Anode Species migrating to anode are Cl- and water. We need to find both species on the right hand side of half equation since oxidation occurs at the anode. The E value for Cl- is very close to E value for H2O. This means the ease of oxidation for both species are similar, E value factor is less significant and concentration is the dominant factor. Since Cl- is concentrated, it will be oxidised at the anode. Topic: Electrochemistry, Physical Chemistry, A Level Chemistry, Singapore Please SUBSCRIBE to my channel and SHARE this video with your friends if you find it helpful! View the full video with description at my website https://chemistryguru.com.sg/how-conc-affects-electrolysis-product This video is extracted from our Chemistry Guru on-demand video lessons. Learn A Level Chemistry online anytime, anywhere and at your own pace! Find out more at https://chemistryguru.com.sg/on-demand-video-lesson