if solid has a greater density than liquid,then how come a cube of ice can float on water?

Question

the teacher gave us this question to think about till tomorow,but i couldn't think of any logical reason.Do u know the answer?

Answer 1

Water is a very unusual substance in that it reaches its maximum density at 3.98°C (39.16°F) in its liquid phase. Thus, ice floats on water, instead of sinking to the bottom.

Aaaargh!

Answer 2

Density=Mass/Volume

We already know that water expands when frozen. If you put water in the freezer and it turns to ice, it still has the same weight or mass.

But as it expands the volume will be larger.

For example.

3/x=y
3/ (x+2)=y

asumming x is a whole positive number, the second formula will turn out as a smaller number equalling a lighter density. (btw this isn't and actual formula for water)

And get some extra credit:

Most substance contract when frozen. Water, along with several other substance such as gallium, bismuth, acetic acid, antimony and silicon all expand and thus all of these substance will have a greater density when liquid then when solid.

HOPE THIS HELPS!

Answer 3

There are two parts to the answer for this question. First, let's take a look at why anything floats. Then, let's examine why ice floats on top of liquid water, instead of sinking to the bottom.
A. A substance floats if it is less dense, or has less mass per unit volume, than other components in a mixture. For example, if you toss a handful of rocks into a bucket of water, the rocks, which are dense compared to the water, will sink. The water, which is less dense than the rocks, will float. Basically, the rocks push the water out of the way, or displace it. For an object to be able to float, it has to displace a weight of fluid equal to its own weight.

Water reaches its maximum density at 4°C (40°F). As it cools further and freezes into ice, it actually becomes less dense. On the other hand, most substances are most dense in their solid (frozen) state than in their liquid state. Water is different because of hydrogen bonding.

A water molecule is made from one oxygen atom and two hydrogen atoms, strongly joined to each other with covalent bonds. Water molecules are also attracted to each other by weaker chemical bonds (hydrogen bonds) between the positively-charged hydrogen atoms and the negatively-charged oxygen atoms of neighboring water molecules. As water cools below 4°C, the hydrogen bonds adjust to hold the negatively charged oxygen atoms apart. This produces a crystal lattice, which is commonly known as 'ice'.

Ice floats because it is about 9% less dense than liquid water. In other words, ice takes up about 9% more space than water, so a liter of ice weighs less than a liter water. The heavier water displaces the lighter ice, so ice floats to the top. One consequence of this is that lakes and rivers freeze from top to bottom, allowing fish to survive even when the surface of a lake has frozen over. If ice sank, the water would be displaced to the top and exposed to the colder temperature, forcing rivers and lakes to fill with ice and freeze solid.

Answer 4

The answer is that not all solids are denser than liquid.

Specifically, when ice forms, it makes a crystal structure, so it actually spreads its molecules out further than if it were the chaos it is in its liquid state.

Most solids that float follow this pattern. Wood for example has a very open structure that entraps large amounts of air in it. So the density of the whole (wood fibers + air) is less than that of water. (Just like a ship made of metal). However, eventually the water seeps into those air voids in the wood and take the place of the air. Then the wood is "waterlogged" and does not float.

Answer 5

Generally, solids are denser than liquids of the same substance. Solid lead, for instance, is denser than liquid lead. Because it is denser, it sinks.
This is not the case for water, however. Ice is less dense than water, therefore it floats.

Ice is less dense than water because of a special type of chemical bonding called hydrogen bonding. A hydrogen bond is a weak bond between a hydrogen atom and an unbonded pair of electrons from another atom.

We can think of a water molecule as being in the shape of an "X" twisted so that the top half is perpendicular to the botton half. In the center of the "X" is an oxygen atom, at the bottom tips of the "X" are two hydrogen atoms, and at the top tips of the "X" are two unbonded electron pairs from oxygen.

As you can see, water molecules are prime candidates for hydrogen bonding between each other.

At warm temperatures, water molecules have a lot of energy and are able to move past and mix with each other despite the attractions between the hydrogen atoms and unbonded electron pairs.

As water is cooled down, however, the molecules have less energy and hydrogen bonding takes over. The molecules form a ordered crystal through hydrogen bonding that spaces the molecules farther apart than when they were in a liquid. This makes ice less dense than water allowing it to float.

Answer 6

Water is an unusual material , It is one of the few materials that has its melting point and boiling point close to each other and near to daily temperatures. Ice expands when it freezes so the particles are farther apart and less dense so ice floats. The molecules are "L" shaped and have to line up to crystalize for ice. Water is most dense at 4 degrees C.

Answer 7

Ice is actually less dense than liquid water. When it freezes, a hydrogen bonds with high bond lengths form to make a crystalline stucture, keeping the water molecules at a greater distance apart.

Answer 8

Water is one of the very few substances which is less dense as a solid than as a liquid. This has a profound impact on the life forms that live in water - because liquid water is more dense than ice, the top of a lake freezes while the bottom stays liquid, allowing the fish to survive. This fact in itself is almost enough to make you believe God planned it that way.

Answer 9

Ahh, the marvels of H2O!
Yes, in most cases, you're right- solids are more dense than liquids. However, in the case of the water molecules, which are held together with hydrogen bonds, the H2O molecules in the ice are actually farter apart than those in the liquid. In that case, there is more unoccupied space in the solid, therefore making it less dense. Good luck! :)

Answer 10

most solids are denser than the liquids from which they freeze - but in the case of water its crytalline structure is determined by a phenomenon known as "hydrogen bonding" in which the hydrogen atoms in H2O bond not only to the oxygen in their own molecule of water but to the oxygen in nearby molecules as well. This causes the molecules to settle into a rigid crystalline structure where the average distance between molecules in the solid is slightly greater than the average distance between molecues in the liquid where they have the freedom of motion to approach each other more closely.