Each student in Ms. Major's class was given an unknown substance. Ms. Major gave her students a list, shown below, of substances and their properties to help them identify their unknown.

Question

Substance Density Boiling Point Appearance
Water 1.0 g/mL 100°C colorless liquid
Ethanol 0.789 g/mL 78.4°C colorless liquid
Sodium Hydroxide 2.13 g/mL 1388°C white solid
Phosphoric Acid 1.685 g/mL 158°C white solid or colorless liquid

If a student's unknown is a colorless liquid and its boiling point was measured to be about 78°C, it is most likely _______.
A.
water
B.
ethanol
C.
sodium hydroxide
D.
phosphoric acid

Answer 1

If the student's unknown is a colorless liquid with a boiling point measured to be about 78°C, it is most likely B. ethanol.

Water has a boiling point of 100°C, sodium hydroxide is a white solid, and phosphoric acid can be a white solid or colorless liquid but has a boiling point of 158°C. The closest match is ethanol, which is a colorless liquid with a boiling point of 78.4°C.