When you drop a super heavy iron anvil into a pool of mercury, something strange happens: the iron anvil does not sink to the bottom, and this is quite an interesting scientific phenomenon.
The science-focused YouTuber CodyDon Reeder has nearly 2 million subscribers on his channel Cody’s Lab. In a recent video, he conducted a unique experiment by pouring mercury into a specialized basin and then dropping a heavy iron anvil weighing about 50 kg inside it. However, the iron anvil did not sink at all; even when manually pushed, it floated like a cork on the surface of the mercury. Why is this the case?
In fact, the buoyancy or sinking of objects significantly depends on the difference in density between the two substances. Density refers to the amount of space that a substance or object occupies, or its volume relative to the amount of material contained within that substance or object, or its mass. Simply put, density relates to the mass of material within a specific space. Elements at the top of the periodic table tend to have lower densities than those further down.
The heavy iron block does not sink in the mercury pool.
When discussing density, mercury is often referenced as a benchmark for other objects. You might be surprised to learn that large mass objects, such as iron bars or weights that usually sink in water can actually float on the surface of mercury.
From a scientific perspective, objects with lower densities will float on those with higher densities and vice versa. According to Archimedes’ principle, any material placed in a fluid will displace a portion of that fluid. The displaced fluid creates an upward buoyant force proportional to the weight of the object. If the buoyant force is greater than the weight of the object, it will float. However, if the buoyant force is less, it cannot support the object, resulting in it sinking.
The iron block cannot sink in mercury.
Mercury is a substance with high density. This metallic element has a density of about 13.5 grams per cubic centimeter – more than 13 times that of water, which is 1 gram per cubic centimeter. Meanwhile, iron sits in the middle, with a density of 7.87 grams per cubic centimeter. Therefore, we can deduce that iron is denser than water. Hence, it will certainly sink when placed on the surface of water. However, mercury is denser than iron, which is why iron floats in mercury.
On the other hand, objects like sponges, wood, and most types of fruits have a density lower than that of water, so they can easily float on the surface of water. Empty bottles and balloons behave similarly because they are filled with air, making them less dense than water.
Mercury is a substance with high density.
Mercury’s high density means that some objects you might consider heavy, like steel ball bearings or weights, will actually float on the surface of mercury. Other metals like copper and nickel, organic materials such as plastics, wood, and stone, as well as certain gases and liquids, which have densities lighter than mercury, will also float in it.
Some substances like iridium with a density of 22.65 grams per cubic centimeter, platinum at 21.4, and gold at 19.3 have densities higher than that of mercury and will sink. Most radioactive elements classified as actinides will also not float in mercury. Uranium has a density of 19.1 grams per cubic centimeter, neptunium is 20.45, while lawrencium measures 16.6.
If you’re curious whether our bodies can float on the surface of mercury, the answer is definitely yes. Considering pure density, you would float on a substantial amount of liquid mercury. This is because the human body is composed of about 65-80% water, which is less dense than mercury. Remember that any object with a lower density will always float on a heavier or higher density substance.
Mercury is a chemical element with the symbol Hg (from the Latin name Hydrargyrum) and atomic number 80. It possesses many distinct properties compared to ordinary metals.
As a heavy metallic element, mercury is the only metal that is liquid at standard temperature and pressure conditions.
Mercury occurs in mineral deposits worldwide primarily as cinnabar (mercury(II) sulfide). The bright red vermilion pigment is obtained by grinding natural cinnabar or synthetic mercury sulfide.
Ancient Chinese and Hindu civilizations were aware of mercury, and it has been found in ancient Egyptian tombs dating back to around 1500 BC. In ancient China, India, and Tibet, mercury was believed to prolong life, heal fractures, and maintain good health. Ancient Greeks used mercury in ointments, while Romans used it in cosmetics. By around 500 BC, mercury was used to create amalgams with other metals. However, in reality, its effects were entirely the opposite.
