Question

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.

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 white solid and its density was calculated to be about 1.7 g/mL, it is most likely _______.
A.
sodium hydroxide
B.
water
C.
phosphoric acid
D.
ethanol

Answer 1

If the student's unknown is a white solid and its density was calculated to be about 1.7 g/mL, it is most likely **C. phosphoric acid**.

Phosphoric acid has a density of 1.685 g/mL and can appear as a white solid or a colorless liquid, fitting the description given. Sodium hydroxide, while it is also a white solid, has a much higher density of 2.13 g/mL, which does not match the calculated density.