Illinois Field Crop Applicators Practice Test

How does temperature generally affect the density of a liquid?

1. Density increases with temperature

2. Density decreases with temperature

3. Density remains constant regardless of temperature

4. Density varies randomly with temperature

The correct answer is: Density decreases with temperature

The relationship between temperature and the density of a liquid is primarily based on the principles of thermal expansion. As temperature increases, the kinetic energy of the molecules within the liquid also increases, causing them to move apart from each other. This increase in molecular motion results in a decrease in density, as density is defined as mass per unit volume. When a liquid is heated, even though its mass remains constant, the increased volume due to thermal expansion leads to a lower density. This phenomenon is observed in most liquids, hence, density generally decreases with temperature. This understanding is fundamental in various applications, including fluid dynamics, environmental science, and even in everyday occurrences such as the behavior of ocean currents or the rising of hot air.