Question

The solutions you will use include KI, NaBr and K2SO4. You will add phenophthalein or bromothymol blue indicator to each solution as directed.

Before proceeding, predict the oxidation and reduction that will occur in each case. Predict the color change of the indicator, if any, that should occur at the anode and cathode in each electrolysis (your textbook should have this information). Predict whether a gas should be formed at the anode or cathode. Remember that water can participate in oxidation/reduction reactions.

the exercise involves electrolysis of aqueous solutions. using a constant current system and stainless steel electrodes.

Answer 1

electuolysis of Na By Anode possibilities 2Br - Br2 +2e- H₂O 402 + 2H+ + 20 So at anode 267-Byg + 2e waction will be Cathode possibilities Nat + 2e Na H₂O + 2 H₂ + 200 E -271 E = -0.330 It Cathode H₂O + 2e H₂ + Ron- H₂ gas will be liberated pink blowe Solution in present of Phenorthele Bromo thymol Blue - yellow Ladent solution hooo Blue - Basic Solution at Cathode (OR)

KI and prinopthalunni undicale snode 21 - In the (Oxidatiert Junction cathode 2H₂O + 2é 20H + H₂ Reduction maction) godide on is oxidized to I2 at anode. Confoem by appearenco Velloro brown Colour in solution... This colour is due to formation of Is reaction is I2 (aq) + J (aq) 3 (a) Tui odide ions st Cathode H2 gas is evolved with pink colour in solution, indication. clonin puusena of phenop thalein unditata T Bromothymol thue will give due to our conso blue colour

Electrolysis of K250g At ano de Toxidation snode 2502 H₂O possibilities S202 +2e 102 + 2H+ +2e E= - 2.010 E = -1.23 V more positive) 22 + 2H+ So at anode H₂O 1 O2 + 2H +2e reaction will occur .O2 on gas will be liberated cathode - Reduction occurs) Possibildies w kt t e K E = -2.92 H₂O + 2e H₂ + 200" E = -0.83v. (more the So at Cathode H2O + 2e H₂ + 20H reaction will occur Hydrogen gas will be liberated at cathode pink colour due to on in presence of phemop thaluin indicator Bromo thymol blue will give blue colour in Cathode & yellow colour in anodile