Water

Turbidity

: Turbidity is a measure of relative clarity of a liquid,and is an optical characteristic of water and is an expression of the amount of light that is scattered by material in the water when a light is shined through the sample. The higher the intensity of scattered light, the higher the turbidity. Causes of tubridity include clay, silt, organic and inorganic matter, algae, plankton, etc. Turbidity makes water cloudy or opaque. Reported in nephelometric turbidity units. During times of low flow, turbidities are usually low(less than 10). In fast moving water or storms there is much higher turbidity. Turbidity affects light concentration, productivity, recreational values, habitat quality, and makes lakes fill faster. Turbidity can make it easier for a water body to become polluted, so turbidity could be sort of a measure or pullution as well. Turbidity in water your going to drink is unapealing and could present a great health risk. It can be a shelter for pathogens, leading to waterborne disease outrbreaks. Turbidity particles provide a shelter for microbes from disenfectants. Turbidity sensors shoot light into water and test how much water is reflected back.

Physical Properties of Water

Adhesion/Cohesion: Cohesion is water being attracted to water, while adhesion is water attracted to other substances. Basically, how 'sticky' water is. If it weren't for gravity, water would stick to you and never let go after a bath, shower, or a swim. Water is highly cohesive, the highest of all non-metallic liquids. Water is cohesive and adhesive because of the charges of its hydrogen and oxygen atoms. The negative oxygen charge connects to other molecules positive hydrogen charge. Water may appear to have a 'skin' holding it together, but it doesn't. This surface tension happens because water molecules tend to attract one another. A water drop naturally occurs in its lowest energy state, or in other words when it is surrounded on all sides by other water molecules, making the drop.

Capillary action:

CA is important for moving water around: "movement of water within the spaces of a porous material due to the forces of adhesion, cohesion, and surface tension.". Water's adhesion to a vessel's walls causes an upward force, resulting in an upward meniscus. Surface tension holds this in tact. When adhesion to walls is greater than cohesion to itself, capillary action occurs. This is limited by surface tension, and gravity. Used when something spills and you dry it and it spreads through paper towel fibers, trees and plants and people, tear fluid, in fountain pens. Putting food colouring in water and having a plant in the water will show that capillary acton works.

Rainbows (light):

More common than rainbows are things called sun dogs, which are formed by light refracting through the ice crystals of cirriform clouds. They are created by falling ice crystals in earths atmosphere. Rainbows happen because the sun causes a white light with different wavelengs in it, and when it gets refracted and bent through water or prisms, these wavelengths visibly split. Rainbows will be bigger and more visible if the water drops in the sky are big, if the sun is close to the horizon. It is possible to see more than 1 rainbow at once, but it is uncommon. Cool fact, rainbow colours in a secondary rainbow are reversed. I didnt understand how it worked though...

Water, the universal solvent:

Water is one of the best and most versatile solvents there are. Thanks to its structure. This is why salt gets dissolved very well in water as well. Both salt and water are polar (atoms have a negative charge side and a positive charge side). Waters bonds are stronger than salts, not to mention since the water completely dominates salt in terms of amount, so many water molecules can "tug" and break away at a salt crystal, using the negative oxygen to pull at the sodium and positive hydrogen to pull at the negative clorine.

Meniscus

: A meniscus is a curve in the surface of a molecular substance(water) when it touches another material. Meniscus happen because of adhesion and has to do with waters fairly high surface tension. Water molecules are attracted to other molecules, but since they also like to stick to water molecules, when they touch the glass they cling and others will too. They go up as far as cohesion and gravity allow. Theres a concave meniscus, which happens when the water molecules of the liquid are attracted to the container(you see it with water). A Convex meniscus happens when the molecules are more attracted to themselves. Theres also flat, which happens when the liquid is not attracted to its container. In any case, you have to read the center of the liquid.

Color

: Everyday water is full of dissolved minerals and such, and pure water is rare. Practically all 'clean' water has a slight hint of blue in it. it's blue because the water molecules are absorbing the red wavelength of light. Water with a bit of Iron dissolved in it leaves a metallic taste. Brown shades of water usually come from rust. Milky, or hazy water usually has some air in it. Colour in seen water can be imparted in two ways, suspended sediments or dissolved matter (tannins). Tannin is caused by organic matter like leaves dissolving into water. Most colour though comes from suspended sediment. Algae and suspended sediments particles are common which cause natural waters to become coloured. The good thing however, is suspended sediment can almost always be filtered out. Suspended sediment may be natural or due to human causes. Dissolved organic matter can be yellow or brown, some algae and stuff can make red or deep yellow, water with lots of plankton and algae is usually green, and soil runnoff makes yellow, red, brown, and gray colours. Water colour is extremely important because it can block light, and light is vital for organisms and ecosystems to flourish underwater.

Heat capacity

: Water has a high heat capacity, or how much energy it takes to raise its temperature by 1. Metals have a very low heat capacity. Since it takes a lot of energy to change waters temperature, this makes it great for regulating our temperatures, and also makes sure many animals underwater dont freeze or boil to death at night.

Compressibility

: Water is practically incompressible, especiialy incompressible. This allows water to shoot out of hoses, fountains, water pistols, etc. In these cases, there is some added pressure and comes shooting out of an opening, rather than compress. However, if you squeeze hard enough, water will compress, shrink and become more dense. This compressed water is so strong it can cut through metal, you need a ton of PSI (Pounds per square inch).

Water Notes

:Earth's surface is literally covered in 70-75% water, and 95% of that water is in the oceans, but only 1-3% of it is actually drinkable water. The human body is around 66% of water, making water so incredibly important and why dehydration is such a scary thing. Not to mention but of that 1-3% clean drinking water, 68.7% is in glaciers and ice caps (which are melting and mixing in with salt water) and 30.1% is made up of ground water, lakes and rivers, which are becoming polluted.

Vapor pressure:

Vapor pressure: The vapor pressure of liquids helps to determine the extent to which molecules in a liquid stay as a liquid or escape into the air as a gas or vapor. For example, added heat to water and raises the normal vapor pressure of water, with the result being water vapor going through the kitchen. The vapor pressure of a liquid is the point at which equilibrium pressure is reached ( in a closed container) between molecules leaving the liquid and entering a gaseous phase and molecules leaving a gaseous phase and entering the liquid one. At equilibrium the movement of molecules between the liquid and gas does not stop, but the number of molecules in the gaseous phase stays the same , there is a certain concentration of molecules in the gaseous phase; the pressure the gas is exerting is the vapor pressure. When the temperature of a liquid is raised, the added energy in the liquid gives the molecules more energy and they have a greater ability to escape the liquid phase and enter the gaseous phase. You can use a pressure container to trick things, because once water hits its boiling point its temperature does not raise.

Density and weight:

Water's density is affected and varies with temperature. The higher the temperature of the water, the less dense and heavy it is. Ice, however, is less dense then water, and this is why about 20% of icebergs are above water. This is essential to life on earth. If water was denser at colder temperatures, water would freeze from the bottom up and kill all life in it, and may not even thaw out. Warmer water sinks to the bottom in the real world. There is something called "heavy ice" which does sink in water. Density is measured with a hydrometer, a straw like device which floats in different parts of water depending on how dense it is, it doesnt just apply to water however.