Dear stack exchange,
For my next lab session we have been tasked to come up with two different methods for determining the concentration of an unknown sample of phosphoric acid.
Design at least two different experimental methods to determine the concentration of the phosphoric acid solution using the materials and equipment provided. (NB: two different volumetric titrations are not two different methods.)
For reference, the "materials and equipment provided" are (along with the standard burettes, pipettes, etc.):
A sample of the phosphoric acid solution
A selection of pH indicators:
- Bromocresol green (range 3.8-5.4)
- Phenolphthalein (range 8.0-10.0)
- Thymolphthalein (range 9.3-10.5)
A standardised NaOH (approximately 0.1 M) solution
A pH meter
One obvious method is an acid-base titration, which is fine, but I have no idea what to do as a second method since we cannot do two different volumetric titrations - perhaps there is some finnicky definition of "volumetric" which means there is another type of titration we can do? It seems as though it has to be something along those lines based on the provided equipment.