Chemistry question

[ranniks]

I have to make a solution with:

titration 1:

- 10mL 0,1 M HCI
- 90mL purified water

I will be adding 1 mL of 0,1 M NaOH with a buret 20 times to observe the change of pH with a pH-meter (so note down the pH 20 times).

What indicator should I use here, and why?

titration 2:

- 10 mL 0,1 M Acetic acid
- 90mL purified water

I will be adding 1 mL of 0,1 M NaOH with a buret 20 times to observe the change of pH with a pH-meter (so note down the pH 20 times).

What indicator should I use here, and why?

[j_menz]

What's HCI ?

[ranniks]

What's HCI ?

My bad. I meant to say HCl

It's hydrogen chloride.

[j_menz]

What are the indicator options in each case? And what are the pH ranges over which they are optimal?

[ranniks]

What are the indicator options in each case? And what are the pH ranges over which they are optimal?

I'm not sure which ones are available. I know at least phenolphthalein is available though..

https://en.wikipedia.org/wiki/Phenolphthalein

[j_menz]

I'm not sure which ones are available. I know at least phenolphthalein is available though..

There's a fuller list here:

https://en.wikipedia.org/wiki/PH_indicator

What you are looking for is one that covers the range of pHs expected during the mix, so look for the transition pH range.

[iansinclair]

No one indicator is going to cover your full range -- but I presume you know that.  Phenolphthalein is a good, reliable solid indicator -- but in this instance I think I would probably have picked bromothymol blue.  Harder to work with, and somewhat harder to see, but better range. your pH meter, though, is going to be what tells you the story, not the indicator.

Be sure to stir! 

[ranniks]

Thanks J_menz and Ian.

In the end there was no other indicator than Phenolphthalein, so we used that.

I'm happy the titration went well.