what method can i use to determine the freezing point of 1h,1h,2h,2h-perfluorooctanol?

Question

i have to come up with a cheap method and write the procedure so please help me somebody....

Answer 1

The freezing point for your material is probably not as cold as dry ice (-78 C), so get some dry ice and acetone and make a cold bath by slowly adding dry ice to a beaker (or better yet a Dewar flask) of acetone.

You will also need a thermocouple or RTD thermometer which can measure this cold.

Keep adding pellets of dry ice one pellet at a time until the temperature is close to -75 C.

Now put some of your fluorochemical in a small glass vial, half full. Attach the vial directly to the thermocouple probe using rubber bands or wire.

Put the probe with attached vial into the cold bath and stir.

The samlpe should freeze. Now keep stirring and allow the bath to slowly warm up. Every 1 or 2 degrees remove the vial and tip it on it's side to see if it is melting yet. Count five seconds. If the liquid does not move, it's still frozen so put it back into the cold bath.

When the liquid first begins to melt, this is the freezing point so write down and report this temperature.

The melting point and freezing point are actually the same. It's better to freeze the sample first and then melt it. If you go the other direction and cool it until it freezes, the liquid can be super-cooled before it actually nucleates and freezes. You will get a more reliable and repeatable result by freezing first then melting.

Answer 2

depends where you think it should be around. put a thermometer in a testtube with the alchol and put it in an ice slurry. if it doesn't freeze start adding salt. if that doesn't work use dry ice in acetone, if that doesn't work liquid nitrogen in ethyl acetate.

Answer 3

There is something with molality you can use. I forget the formula but it involves molality, number of ions, and the change in temperature of something.