AP BIOLOGY

Detailed explanation-1: -Water’s lower density in its solid form is due to the way hydrogen bonds are oriented as it freezes. Specifically, in ice, the water molecules are pushed farther apart than they are in liquid water. That means water expands when it freezes.

Detailed explanation-2: -The extra hydrogen bonds that occur when water freezes increase the space between molecules, causing a decrease in overall density. In fact, each water ice molecule forms hydrogen bonds with four other molecules, while water molecules only form hydrogen bonds with an average of 3.4 other molecules.

Detailed explanation-3: -Water density changes with temperature and salinity. When water freezes at 0°C, a rigid open lattice (like a web) of hydrogen-bonded molecules is formed. It is this open structure that makes ice less dense than liquid water. This is why icebergs float.

Detailed explanation-4: -When frozen, water molecules take a more defined shape and arrange themselves in six-sided crystalline structures. The crystalline arrangement is less dense than that of the molecules in liquid form which makes the ice less dense than the liquid water. When water freezes, the volume expands by approximately 9%.

Detailed explanation-5: -Cohesion: Hydrogen Bonds Make Water Sticky The property of cohesion describes the ability of water molecules to be attracted to other water molecules, which allows water to be a “sticky” liquid.