Water is a nearly universal solvent. That means it can dissolve many substances, or solutes. Substances that dissolve in water are called hydrophilic, and substances that don’t dissolve in water are called hydrophobic. One example of a hydrophilic substance is salt. When salt and water combine, they form a homogeneous solution that can’t easily be separated. The oceans are filled with saltwater, as are our tears. One example of a hydrophobic substance is oil. It resists combining with water and naturally separates.

Question

Water is a nearly universal solvent. That means it can dissolve many substances, or solutes. Substances that dissolve in water are called hydrophilic, and substances that don’t dissolve in water are called hydrophobic. One example of a hydrophilic substance is salt. When salt and water combine, they form a homogeneous solution that can’t easily be separated. The oceans are filled with saltwater, as are our tears. One example of a hydrophobic substance is oil. It resists combining with water and naturally separates.

Shabbir added an unknown substance to a bottle of water and shook the bottle until the two substances were combined. Then he set the bottle aside for 30 minutes. When he came back, the unknown substance had settled on the bottom of the bottle, and the water had risen to the top. Based on Shabbir’s experiment, what can you tell about the unknown substance?

A
It is hydrophilic.

B
It is a type of oil.

C
It is hydrophobic.

D
It is a homogeneous solution.

Answer 1

C. It is hydrophobic.

Since the unknown substance settled at the bottom of the bottle and did not mix with the water, it shows characteristics of being hydrophobic, meaning it does not dissolve in water.