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.
water
B.
sodium hydroxide
C.
phosphoric acid
D.
ethanol

Answer 1

If the student's unknown is a white solid with a density of about 1.7 g/mL, it is most likely **C. phosphoric acid**.

Sodium hydroxide has a higher density (2.13 g/mL) and is also a white solid, but it doesn't match the density of the unknown. Phosphoric acid has a density (1.685 g/mL) that is close to the stated density of 1.7 g/mL and can be either a white solid or a colorless liquid, making it the most appropriate choice based on the provided data.