posted by lon .
i have to do a lab on finding the melting point , but i do not understand these instructions : for the known sample raise the temp until it is within 10 to 20 C of known value, and then lower the rate of heating to 2-3 C per minute
please explain with the temperature of 120 C
If the known melting temp is say 450C, raise the temperature of the surrounding water bath to 440, then turn down the heat low, so the temperature slowly rises, at a slow rate, say 2C per minute.
If you went fast, you would miss the melting point, as there is only a brief time the sample stays at constant temperature before it melts. You don't want to miss it going by.