Australia's Science Forum

Hello oh wise ones!

I have been requested to prepare a prac that uses 0.1 M Calcium Fluoride. I tried to make it up but it wouldn't dissolve. I then googled and found that it is highly insoluble and will only dissolve to about 0.01M in water. Should I be dissolving it in something else?

Any suggestions appreciated! Thanks.

Go back and talk to the teacher. Let them know what you found out. They may be happy with 0.01M or they have given you the wrong chemical - it happens!
Don't feel bad about chatting to the teacher. We all make mistakes.

Merilyn1 wrote: ↑18 Oct 2022, 08:44 Don't feel bad about chatting to the teacher. We all make mistakes.

Absolutely Merilyn , I must drive my teachers bonkers at times , but better they know ahead of time if there are issues .

regarding the Calcium Fluoride , sometimes teachers deliberately ask for the impossible .In this case they may well know its insoluble , and that's the whole object for the class room to see. .......but you won't know unless you ask .

I made up a 0.1M solution of calcium fluoride last week and got a cloudy solution with some left on the bottom, so some of it dissolved. Interestingly, CaF2 is so insoluble that the labelling program on RiskAssess won't allow for the concentration to be listed - it assumes you're labelling the solid.

Merilyn1 wrote: ↑18 Oct 2022, 08:44 Go back and talk to the teacher. Let them know what you found out. They may be happy with 0.01M or they have given you the wrong chemical - it happens!
Don't feel bad about chatting to the teacher. We all make mistakes.

Thank you. Yes, that was my plan. Just thought I'd see if anyone on here had any ideas first. The prac is in a printed textbook, so I figured it must have been done before.

Marama T wrote: ↑18 Oct 2022, 09:23 I made up a 0.1M solution of calcium fluoride last week and got a cloudy solution with some left on the bottom, so some of it dissolved. Interestingly, CaF2 is so insoluble that the labelling program on RiskAssess won't allow for the concentration to be listed - it assumes you're labelling the solid.

Yes, that's how mine looks too. It will probably still work I guess....