The half-reactions that occur in ordinary alkaline batteries can be written as In 1999, researchers in Israel reported a new type of alkaline battery, called a 'super-iron' battery. This battery uses the same anode reaction as an ordinary alkaline battery but involves the reduction of FeO₄^2- ion (from K₂FeO₄) to solid Fe(OH)₃ at the cathode. (b) Write a balanced equation for the cathode half-reaction in a super-iron battery. The half-reaction occurs in a basic environment.

Video transcript

Hello. In this problem we're told alkaline fuel cells with potassium hydroxide is the electrolyte Was used by NASA for the Space Apollo and Gemini missions this operates between 25 to approximately 250°C with an efficiency of and involves a reduction of oxygen gas to hydroxide ions. At the cathode shown below are the N a half reaction. And the overall cell reaction were asked to write the balanced cathode half reaction in an alkaline fuel cell. So we're told that the reaction taking place at the cathode is the reduction of oxygen. Gas form hydroxide means so we'll balance the oxygen by adding water. So we need one water to balance the oxygen well. Then balance the hydrogen by adding hydrogen ions. We have three on the product side. So we need three on the reacting side and next will balance the charge is plus three on the reacting side, minus on the product side. So we'll add four electrons to the reacting side. Well then at our reaction taking place at the an ode which is hydrogen gas reacting with the director lines form water. When we combine these two half reactions. Then we see that the moles of electrons gained is equal to those lost. So those cancel we also have four hydroxide on the reactive side, one on the product side. So one of those will cancel on the reacting side. And we then have three hydro nines and three hydroxide ions. So those will form three waters we have a total of five waters on the product side. So three waters on the reactive side will cancel With three on the product side. And we'll be left within two waters on the product side writing what's left over. Then we have two moles of hydrogen gas plus oxygen gas. Most form two moles of water, which is the overall cell reaction that we were provided. So taking our reaction at the cathode, we have four moles of electrons to us. three moles of hydrogen ions, plus oxygen gas goes to form hydroxide plus water. So this is taking place in an alkaline fuel cell. So that means we need to neutralize our hydrogen ions by adding equal number of hydroxide ions. So we're gonna add three hydroxide ions. And in doing that we have to do it to both sides. So we then end up with formals of electrons Plus three moles of water. That's oxygen gas, most foreign formals of hydroxide ins plus water. So we can eliminate then Water on the product side with one on the reacting side. And so our balanced reaction and taking place at the cathode in an outlying fuel cell will be water plus oxygen gas going to form or hydroxide. And this then corresponds to answer. Be thanks for watching. Hope this helped