39degF Water is the densest at 39 degrees Fahrenheit (or 3.98 degrees Celsius). This is due to the fact that the molecules are closest together at this temperature. The weight of the water increases as it gets colder.
The density of water decreases as the temperature increases. At 100 degrees Fahrenheit (or 38 degrees Celsius), water is half its volume at room temperature. A cube foot of water at 100 degrees F will only hold 57.14 cubic feet compared to 80 cubic feet at 0 degrees F.
The weight of the water increases as the temperature decreases. At 0 degrees F, the water is half its volume and weighs less than at 100 degrees F. A cube foot of water at 0 degrees F will weigh 62.5 pounds compared to 80 pounds at 100 degrees F.
H2O molecules bond together more tightly when they're closer together. So, at a given pressure, the H2O molecule becomes heavier as temperature goes up because there's more space between their atoms. And lower down concentration, the H2O molecule becomes lighter because there are more gaps between them.
Water is the densest at 39 degrees Fahrenheit (or 3.98 degrees Celsius). This is due to the fact that water's molecular structure and hydrogen bonding take up more space when it is frozen solid than when it is a warmer liquid. In other words, even though the water is hardening into ice, the molecules are more apart. This leaves more room for them to be dense.
Ice floats on water because there are gaps between the ice crystals. This is also why ice cream works: There are lots of small holes in it so it doesn't sink like a rock.
Frozen water is called "glass" because it can break if hit with enough force. When water is liquid, its molecules are close together and there isn't much space between them.
The reason ice is less dense than liquid water is because the ice crystals are not touching. There are spaces in between each one that could hold more water. The same thing happens when you freeze a liquid: The molecules get closer and closer until they reach space where there's nothing else they can go to. That's why freezing liquids makes them more dense.
Gases are made up of tiny particles that don't touch. Between each particle is empty space that the gas molecule can fill. So gases are very dense.
Liquid gases such as argon or helium are called "superfluids" because they conduct electricity without resistance.
Water with a temperature of 4 degrees Celsius has a higher density. Explanation: Density is connected to the mass-to-volume ratio. Water expands as it is chilled or heated. As it approaches freezing temperature, it begins to contract again when it reaches its normal boiling point.
Ice, on the other hand, does not expand when it is cooled down; this is why frozen ponds and lakes do not break their bonds and float away if they are cut into pieces with an axe or thrown into the lake from a high vantage point. If you drop a rock into a puddle of icy water, it will not disappear because it is covering more area than a volume-sized piece of ice.
As ice melts, it becomes liquid again - water. So, ice must have a greater density than water. In fact, ice weighs more per unit volume than water at any given temperature. The difference in weight between solid ice and liquid water varies with the temperature. At 0 degrees Celsius, it is 1.8 times as much; at 32 degrees Celsius, it is 1.6 times as much.
The question here is: What is the temperature of the water in that example? Since we are comparing weights of equal volumes of ice and water, we need to make sure they have the same temperature.