We all love to have our drinks cold. Either we add cold water to our drink or simply toss in some ice cubes. But have you ever wondered when you add sugar to water, it goes right down to the bottom of your glass, but when you add ice cubes, they float instead of sinking. We will help you find an answer...
Everyday Chemistry - Why does ice always float and not sink?
We either add cold water or simply toss in some ice cubes to enjoy chilled drinks. But have you noticed that ice cubes always float in water instead of sinking? Here's why...
Why does ice float?
Ice is the solid state of water. Density plays a vital role in ice floating on water. Density is the qualitative property of any material and is calculated as mass per unit volume. Ice is denser than water and hence it always floats. Ice does not follow the basic rules of thermodynamics. According to this theory, a solid mass is heavier than water and will sink, but ice instead of sinking, floats on water.
Liquids tend to contract on cooling. The individual, free molecules of liquid slow down and stay till the matter turns solid. Water also contracts but only up to a certain point. As the temperature drops, molecules slow down and start contracting. Once the temperature reaches 4°C, water begins to expand. This unique property of ice lies in its molecular structure.
The molecular structure of water
Water contains two atoms of hydrogen and one atom of oxygen. These atoms share electrons with one another. The atoms are negatively charged and tend to pull the hydrogen atoms. The water molecules are attracted to each other because of this and get positively charged because of the hydrogen atoms.
This bonding between the water molecules is known as hydrogen bonding.
In a glass of water, the molecules keep running here and there. Thus both positive and negative atoms exist and there is attraction between the molecules.
Water has some density and so do ice cubes. However ice cubes have lesser density than water and hence they float in water.
Why does ice sink in alcohol?
Although ice floats in water, when it's added to alcohol, it sinks. This is because ice cubes have a higher molecular density compared to alcohol.