FUEL CELLS

 Dear students,

Check out this post to explore about fuel cells.. the future...

A fuel cell is an electrochemical cell that converts chemical energy (energy stored in bonds) into electrical energy by electrochemical reaction. These cells require a continuous input of fuel and oxygen as an oxidizing agent in order to sustain the reactions that generate the electricity.

Hydrogen Fuel Cell:

One of the most successful fuel cells uses the reaction of hydrogen as a fuel with oxygen to generate electricity. It consists of an electrolytic solution such as 25% KOH and two inert porous electrodes. Hydrogen and oxygen gases are bubbled through the anode and cathode compartment respectively where the following reaction takes place.

At Anode: hydrogen molecules are oxidized with the liberation of electrons, which then combine with hydroxide ions to form water.

At Catode: The electrons are absorbed by oxygen to form hydroxide ions.

The standard emf of the cell is given by 1.23 V. Therefore 80% of chemical energy is converted into electrical energy.

Determination of pH.

 Dear Students,

This post discuss the pH determination by colorimetric method. Two videos are attached for easy understanding.

Determination of pH:

pH determination measures the acidity or alkalinity of a solution using pH paper, indicators, or a pH meter to find hydrogen ion concentration. 

Methods: 

Electrometric Method (pH Meter): This is the most accurate method, utilizing a glass electrode to detect electromotive force (EMF) generated by hydrogen ions, often utilizing two- or three-point calibration with buffer solutions.

Colorimetric Method (pH Paper/Indicators): A less precise method involving pH paper or universal indicators that change color, which is then compared against a standard chart.

Working Principle:

The pH is measured by noting the various colour changes in this method. A universal indicator (e.g., B.D.H. universal indicator) and various buffer solutions in the pH range 3 to 11 are prepared. A drop of universal indicator is added to each buffer solution and the colour change is noted. Then, few drops of universal indicator are added to the solution of unknown pH. The colour of this solution is compared with the suitable buffer solution and the pH may be determined. Comparators are employed for the matching of colour tints. Hellige comparator is generally used in water analysis.