There are etched or marked lines on the device so the user can see how high or low the hydrometer is floating. The hydrometer is gently lowered into the liquid to be measured until the hydrometer floats freely. It consists of a cylindrical stem and a weighted bulb at the bottom to make it float upright. More often, though, it is made of glass and looks a lot like a thermometer. It is one of the simplest of scientific-measuring devices, and you can even make your own out of a plastic straws (see links below). The instrument to measure the density of a liquid is called a hydrometer. As more material is dissolved in a gallon of water then that gallon will weigh more and be more dense- ocean water is denser than pure water.Ī hydrometer is used to measure density of a liquid. Water in nature contains minerals, gasses, salts, and even pesticides and bacteria, some of which are dissolved. The real-world explanation of water density is actually more complicated, as the density of water also varies with the amount of material that is dissolved in it. And, with water being such a good insulator (due to its heat capacity), some frozen lakes might not totally thaw in summer. If water was most dense at the freezing point, then in winter the very cold water at the surface of lakes would sink, the lake could freeze from the bottom up. Since water at about 39☏ (4☌) is more dense than water at 32☏ (0☌), in lakes and other water bodies the denser water sinks below less-dense water. This property of water is critical for all life on earth. That means that about 10 percent of an ice cube (or iceberg) will be above the water line. The density of ice is about 90 percent that of water, but that can vary because ice can contain air, too. Again, lucky for us, as we would not hear that delightful tinkle of ice cubes against the side of a glass if the ice in our ice tea sank to the bottom.

It happens that the lattice arrangement allows water molecules to be more spread out than in a liquid, and, thus, ice is less dense than water. Ice actually has a very different structure than liquid water, in that the molecules align themselves in a regular lattice rather than more randomly as in the liquid form. The best way to visualize how water can have different densities is to look at the frozen form of water. Most of an iceberg exists below the water surface. Sources/Usage: Some content may have restrictions. Upon freezing, the density of ice decreases by about 9 percent. This is due to ice's density being less than liquid water's density. This is not a surprise, but actually almost all of the volume of an iceberg is below the water line, not above it.

If you look at this picture you can see that some of the iceberg is below the water level. The Water Encyclopedia, Third Edition, Hydrologic Data and Internet Resources, Edited by Pedro Fierro, Jr.Īnd Evan K. Department of the Interior, Bureau of Reclaimation, 1977, Ground Water Manual, from So, when they demanded another gallon of water, I consulted the 'Internet' of that day-an encyclopedia- and found out that a gallon of water at the boiling point only weighed 7.996 pounds! I ran up the hill carrying my gallon of water that weighed 0.333 pounds less and ran back down even faster, their angry voices fading behind me. That gallon of tap water at 70☏ weighed 8.329 pounds, which was a lot for a 70-pound kid to haul up a huge hill. They got thirsty and made me go back home and bring them a gallon of water. One hot summer day they climbed the huge hill next to our house to dig a hole to hide their bottle-cap collection. I was able to use water density once to at least play a trick on them, though. Growing up with an older brother was difficult, especially when he had his friends over, for their favorite activity was thinking of ways to antagonize me. The rounded value of 1 g/ml is what you'll most often see, though. A common unit of measurement for water's density is gram per milliliter (1 g/ml) or 1 gram per cubic centimeter (1 g/cm 3).Īctually, the exact density of water is not really 1 g/ml, but rather a bit less (very, very little less), at 0.9998395 g/ml at 4.0° Celsius (39.2° Fahrenheit).

Density is just the weight for a chosen amount (volume) of the material. As long as an object is made up of molecules, and thus has size or mass, it has a density. The definition of density, makes a lot more sense with a little bit of explanation. If you're not still in school, then you probably forgot you ever even heard it. On Earth, you can assume mass is the same as weight, if that makes it easier. If you're still in school, you've probably heard this statement in your science class: ' Density is the mass per unit volume of a substance'.

Density of water in english units