Laboratory Investigation and Chromatography Analysis

Extract

[...] 1b) Removal of copper from the color : Copper has a characteristic color that is reddish-brown or brown-red, and not grey. Given that the solid found is described as being of color grey, We can immediately rule out copper as a candidate, since its color does not match that of the observed solid. [...]

[...] The liquid that forms a homogeneous mixture with water is formic acid, and the one that forms two separate phases is cyclohexane. Identification of liquids without using water : Yes, we could have identified the two liquids without using water, by comparing their temperatures of boiling. - Method : Heat the two liquids and measure the temperature at which each one begins to boil. ? The liquid that boils around 80.7°C is the cyclohexane. ? The liquids that boil around 100.8°C is theformic acid. [...]

[...] Boiling point = 80.7°C (it starts to boil beyond this temperature). As the ambient temperature (20°C) is between the melting point (6.5°C) and the boiling point (80.7°C), the cyclohexane is in the state liquid at 20°C. - Formic acid : ? Melting point = 8.4°C (it is solid below this temperature). ? Boiling point = 100.8°C. Similarly, the ambient temperature (20°C) is between 8.4°C and 100.8°C, so formic acid is also in the state of liquid at 20°C. Thus, the two substances are liquids at ambient temperature. [...]

[...] The line drawn at the top of the chromatogram corresponds to the front of the eluent. This is the maximum position reached by the eluent after a certain migration time. This line allows measuring the distance traveled by each substance (the distance between the initial deposit and the position of each spot), in order to calculate their frontal ratio which allows identifying the substances. It was necessary to reveal the chromatogram to the ultraviolets because some substances are not not visible to the naked eye. [...]