4. Taking a Melting Point: Packing Pack the capillary tube by pressing the open end gently into a sample of the compound to be analyzed. (Capillary tubes break easily!) The solid should fill the tube to a depth of ~ 2 mm. Tap the bottom of the capillary on a hard surface so that the crystals pack down into the bottom of the tube.
5. Melting Point Apparatus Pack the crystals at the bottom of the tube and place the tube in the slot behind the eye-piece on the Mel-Temp. Turn on the Mel-Temp and turn the knob to adjust heating rate (not too fast or too slow). Watch through eyepiece and record temperature at which the crystals first begin to liquefy and record temperature at which the entire sample is liquid (mp range)
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8. Part II – Eutectic Temperature (skip this) Unknown mp = 133-135 °C Benzoin (mp = 135-137°C) or trans -Cinnamic Acid (mp = 133-134°C) mp = 135-137°C Unknown is Benzoin mp << 133°C Unknown is not Benzoin mp << 133°C Unknown is not trans -Cinnamic Acid mp = 133- 134°C Unknown is trans -Cinnamic Acid Mix Unknown and Benzoin Mix Unknown and trans -Cinnamic Acid