Why Does Ice Float on Water? ~ BZU SCIENCE

When we drop ice into water, a question comes to our mind that why does ice float on water rather than sinking. To understand the answer to this question, we try to divide this question into two parts. First of all, we try to know ‘Why does anything float on water?’. Secondly, we try to know ‘Why does anything sink in the water?’. After getting answers to these questions, we can understand the answer to the actual question.

Why Does Anything Sink in the Water?

If we drop anything into the water and it sinks, it means that thing is denser than water. In other words, this thing has a greater mass per unit volume than water. The density of water is 997 kg/m³. If we drop anything into the water whose density is greater than water, it will sink into the water. For example, if we drop a small part of iron into the water, it will sink into the water. Its reason is that iron has a density of 7873 kg/m³. This density of iron is much greater than the density of water.

Why Does Anything Float on Water?

If we drop anything in the water and it floats on the surface of the water, it means that water is denser than that thing. In other words, we can also say that this thing has less mass per unit volume than water. If we drop wood in the water, it will float on the surface of the water. It means that it will not sink. Its reason is that the density of the wood is from 320 kg/m³ to 550 kg/m³. On the other hand, the density of water is 997 kg/m³. This difference in the density prevents the wood from sinking into the water. Due to this reason, wood floats on the surface of the water.

Why Does Ice Float on Water?

From the above discussion, you can get an idea of why water float on water. Water has a peculiar behaviour than other solids. Its reason is that on cooling, water converts into ice. Its density decreases rather than increasing like other solids. Water has a maximum density at 4-degree centigrade. If we further cool it, at zero degrees centigrade, it converts into ice. As a result, the distance between their molecules increases. The density of ice decreases than the density of water. When we drop ice in the water, it floats on the water. Its reason is that the density of ice is 917 kg/m³ which is less than the density of water 997 kg/m³.

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Why Does Water Show Peculiar Behaviour?

It is due to the hydrogen bonding. As we know that a water molecule is made up of one oxygen atom and two hydrogen atoms. One oxygen atom and two hydrogen atoms in a water molecule are strongly attached. They are attached with the help of covalent bonds. Between the positively charged hydrogen atoms and negatively charged oxygen atoms, there are weaker hydrogen bonds. These weaker hydrogen bonds become the cause of the attraction of the water molecules. When we cool water below 4-degree centigrade, these hydrogen bonds adjust the negatively charged oxygen atoms apart from the positively charged hydrogen atoms. As a result, crystals are formed. We can these crystals ice.

Why Does Heavy Water Ice Sink?

Sometimes, we see that ice sinks in the regular water. If you make ice by using heavy water, it will not float on the surface of the water. Its reason is that heavy water ice contains the deuterium isotope of Hydrogen. No doubt, it has Hydrogen bonding but it can’t offset the mass difference between heavy water and normal water. Another amazing fact is that heavy water ice also sinks in heavy water.