Answer:
a) The functional group that will be evident in the IR spectrum is the OH group.
b) OH group appears between 3200-3600 cm⁻¹
c) An important impurity that have the same functional group is water.
Explanation:
Eugenol is a chemical substance that consist in a benzene that have in 1 an alcohol, in position 2 a methyl ether and in position 4 an 1-propene bonded by the terminal alkyl carbon.
a) Having this in mind, the functional group that will be evident in the IR spectrum is the OH group.
b) This OH group appears between 3200-3600 cm⁻¹
c) An important impurity that have the same functional group is water. When you have water in your sample a big signal will appear in this zone and it is possible that overlapes the OH signal of eugenol.
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The researcher may first weight the beaker with water and then start to heat the water to a constant temperature, for example 30 °C and then start adding salt and stirring. He should add salt slowly until solid salt starts to become visible and the solution starts becoming cloudy. When this happens, he should quickly weigh the beaker. The increase in mass is the mass of salt dissolved at that temperature.
The procedure is then repeated but at an increased temperature until 5-6 temperatures have been tested.