a) Compound X has a literature melting point of 145-147°C. You take the melting point of pure X. Which of the following melting observed melting ranges can ONLY be due to thermometer calibration AND NO OTHER source of error. Assume all precautions for packing the melting point capillary was adhered to. [ Select ] ["142-151° C", "135-141° C", "149-151° C"]
b) You have been given a white solid that has a melting point of 180-182ºC and you suspect that it is NOT 4-toluic acid (mp: 180-182ºC). What would you observe about the melting point if the unknown were mixed with and equal quantity of 4-toluic acid if your suspicion is true? [ Select ] ["mp stays the same", "mp goes up", "mp goes down"]
c) When packing a solid sample in a melting point capillary BEFORE placing it in the melting point apparatus, what is the immediate next step AFTER creating a pile of dry and finely powdered sample? [ Select ] ["Tap closed end of melting point capillary on hard surface", "Force closed end of melting point capillary into sample", "Force open end of melting point capillary into sample", "ap open end of melting point capillary on hard surface"]