Question

Which wire is made of a mixture of substance and has a specific melting point?​

Answer 1

Answer:

Determining the melting point of a compound is one way to test if the substance is pure. A pure substance generally has a melting range (the difference between the temperature where the sample starts to melt and the temperature where melting is complete) of one or two degrees. Impurities tend to depress and broaden the melting range so the purified sample should have a higher and smaller melting range than the original, impure sample.

MEL-TEMP apparatus

Fill a capillary tube with crystals about 3 mm high. Put the capillary tube (open end down) into the crystals and tap it on the bottom of the crystallization dish to get the crystals into the tube. Force the crystals to slide to the bottom of the tube using one of the following methods: tap the tube (open end up) on the lab bench; drop the capillary tube through a 2-3 foot piece of glass tubing; or rub the capillary tube along a piece of wire gauze.

Place the capillary tube in the MEL-TEMP melting point apparatus. Set the MEL-TEMP at a high enough level to make a rapid determination of melting point. Observe the melting process though the magnifying lens.

Once a melting point range is determined, prepare another capillary tube (tubes should only be used once and then discarded) and set the MEL-TEMP to the appropriate power level, based on the power level/temperature chart. This time, make sure that the increase in temperature is no more than 2oC per minute. Again, observe through the lens.

Explanation: