Polarity of Water • Water molecules consists of two hydrogen atoms bonded to an oxygen atom. • The Hydrogen atom has a slight positive pole and the oxygen has a slightly negative pole. • This feature is called polarity.
Bonding in water • A bond can form between the positive pole of a water molecule and the negative pole of another molecule. • This is called a Hydrogen bond. • Water is cohesion and adhesion which means; Cohesion; sticks together with other water molecules and Adhesion; sticks to other polar surfaces. • If it wasn’t for hydrogen bonding evaporate and be a gas at normal room temperature (20-24 degrees Celsius) • When the water freezes the volume and density of the water may increase.
Relations between properties of water and it’s uses in living organisms. • Strong pulling forces sucks the water up to the top of the tallest trees in their transport system. They rarely break because of how strong the bond is. Water is used as transport in the xylem for plants(Xylems are vessels in the wood and they act as transport tubes). • Most chemical reactions in living organisms take place with all the substances dissolved in water. Water is the medium for metabolic reactions. • There’s also a wide range of molecular compounds which also dissolves in water; including sugars, amino acids, small nucleic acids and proteins • Water is not only used as a transport medium for plants but also for animals. • Blood is mainly consistent of water and can carry heat to cooler parts of the body. • Water is below freezing point everywhere, but in most areas it’s above freezing point – as a liquid it can act as a medium for metabolic reactions. • Water can also be used as a coolant. When humans swear or when plants transpirations it cools us / them down.
Properties of Water listed • Cohesion: Water molecules stick to each other because of the hydrogen bonds that form between them. • Solvent properties: Many different substances dissolve in water, for example organic substances with polar molecules, for example glucose. • Thermal properties, heat capacity: It has a large heat capacity because of great masses needs a lot of energy to break the hydrogen bonds. • Thermal properties, boiling point: is 100 degrees Celsius, to convert it from liquid to gas ALL the hydrogen bonds need to be broken. Thermal properties the cooling effect of evaporation: Water can evaporate at temperatures below boiling point. The bonds have to be broken to do so, the heat is taken from liquid water, cooling it down.
Water has a high heat capacity Water has a high heat capacity and as I wrote before the reason for this is the hydrogen bonds. Here is some examples to see how much heat it takes to raise the temeperature; 100 degrees at sea level while it only takes 68 degrees to boil at the top of Mount Everest. As much as it takes for water to boil it’s good for the animals that lives underwater, it means that they can regulate their internal temperature by a steady tempo instead of being affected by sudden changes in temperature above water. Fish is an example of that.
Properties of Water • All the hydrogen bondings in the water causes it to have a high surface tension. Which is why some insects / beetles can float on water. Like water beetles. • Other animals can walk on water because of this high tension such as the Jesus Lizard. (To all of you who didn’t know, the bible claims that Jesus did some water walking, hence the name). • Frozen water is less dense than liquid water. As water decreases in temperature the water molecules moves closer together. • When it gets below freezing point and some of the water freezes, it does that to prevent the rest of the water freezing and that’s why it creates the crust.
pH scale for Water • Here is the pH scale for water.