Right, so I'm doing A2 OCR Chemistry coursework right now, and am evaluating an experiment with two methods to find the formula of hydrated iron(II) sulphate crystals. One was a standard heat-a-crucible-full-of-the-stuff jobbie, and I'm fine with the many possible procedural errors and improvements with that, but the other is a titration, and I'm not too sure of any improvements that could be made to the titration procedure. I had thought about some equipment that could tell when the solution had changed colour, thus letting you know when to stop adding to it, but I'm not sure if there is even such a piece of equipment? Any other ideas would be great too. Thanks.
I've done percentage errors, that's the Measurement Errors section. I'm stuck on the Procedural Errors section, although I just put some rubbish about a pH meter, to let you know of the end-point for the titration. It'll do I suppose. Thanks for trying to help anyway.
Maybe you could use a colorimeter to measure the light intensity through the solution (at least I think that's how they work, you might want to check up on that...) I suppose you could put a piece of white paper under the conical flask so you can see the colour change more clearly?
Maybe I'm not understanding this 100%, but in my mind procedural changes would include arranging the titration to have bigger titres (reducing errors), and using larger aliquots (reducing errors). Similarly you could choose standards that have a larger molecular mass (to reduce error percentages when weighing). you could also carry out the titration more times to ensure that the endpoint is more accurate. If it's an acid base titration involving a weak acid (or base) you could involve some kind of conductimetric meter to get the end point via ion concentrations (but as a good titration depends on one drop of titrant then this couldn't improve on it)
Procedure is just that - what you actually do. Using a colourimeter or any other measuring device does not improve the experiment as the weakest point is the one drop of titrant that leaves the burette. Any procedural improvement would have to improve on that.
Well we already had a white tile beneath the flask to help you see the colour change easily, and we also redid it until we got answers within 0.1 of each other. I think I'm gonna go with colorimeter, as it makes more sense than the pH meter, although I'm still unsure. It measures absorptions of light, and so the colour change will alter the absorption, letting you know when the end-point is, no?
the only "improvement" that makes common sense is to get rid of the burette and replace it with a fine capillary injection colorimetry detection computer controlled system. Hmm, got plenty of those lying around.