I've never really though about this until now.
When a question says something like, a 30cm3 sample is diluted by 50cm3 water, find the pH of the solution formed.
Should you take into account the moles of H+ that is in the water that is added (1) or would you just assume that the water doesn't dissociate at all (2). I have always assumed it is the latter but when thinking about it to get a more accurate answer you should consider the dissociation of water right? I know to 2dp it wouldn't usually make any difference but t would lose method marks right.
Which one is correct and more importantly which one should I use in an exam?
pH calculations (simple) watch
- Thread Starter
- 17-05-2016 00:37
- 17-05-2016 08:09
pH calcs will always be done at concs so low that you can forget about the ionisation of water.
Use your latter thought, esp. in exams.