Properties of Water PDF

2.2 Properties of Water Water is an inorganic compound essential for sustenance of all forms of It is present in all living cells in life. It is the predominant different proportions ranging compound present in all from 70% to 95%. living systems. The...

2.2 Properties of Water Water is an inorganic compound essential for sustenance of all forms of It is present in all living cells in life. It is the predominant different proportions ranging compound present in all from 70% to 95%. living systems. The human body is made up of 70% water that is distributed differently among different types of cells. For example, our brain cells have 85% water while bone cells have only 20%. Water is not limited to living systems only, as it covers more than 71% of our earth. https://alevelbiology.co.uk/ 2.2 Properties of Water Water’s unique properties allow life to exist on Earth. Life depends on hydrogen bonds in water. Water is a polar covalent molecule. – Polar molecules have slightly charged regions. _ O H H + + – Nonpolar molecules do not have charged regions. 2.2 Properties of Water Life depends on hydrogen bonds in water Hydrogen bonds form between slightly positive hydrogen atoms and slightly negative atoms. 2.2 Properties of Water Hydrogen bonds are responsible for four important properties of water. 1. universal solvent (adhesion) 2. high specific heat 3. surface tension (cohesion/polar) 4. less dense as a solid Fig. The water's surface (left, dyed red) is curved down because water has greater adhesion than cohesion. The surface of the mercury (right) is curved up because mercury has greater cohesion than adhesion. 2.2 Properties of Water Examples of each property of water Universal solvent (adhesion) – the attraction among molecules of different substances is called adhesion. In other words, water is “sticky” to lots of other substances. transpiration Example: Adhesion helps plants transport water from their roots to their leaves because water sticks to the sides of cellular structures in plants called xylem. 2.2 Properties of Water 2.2 Properties of Water Examples of each property of water High specific heat – hydrogen bonds give water abnormally high specific heat. This means water resists changes in temperature. Water also helps maintain homeostasis inside cells by keeping temperatures stable. For instance, our fish in the pond is indeed happy because the heat capacity of the water in his pond above means the temperature of the water will stay relatively the same from day to night. He doesn't have to worry about either turning on his air conditioner or putting on his woolen flipper gloves. 2.2 Properties of Water Examples of each property of water Cohesion is the attraction among molecules of a substance. In other words, water is “sticking” to other water molecules due to hydrogen bonds. Fig. Water’s surface tension comes from hydrogen bond’s that cause water molecules to stick together. 2.2 Properties of Water Examples of each property of water Water is less dense as a solid due to its hydrogen bonds. Compare: How are hydrogen bonds similar to ionic bonds? 2.2 Properties of Water Many compounds dissolve in water. A solution is formed when one substance dissolves in another. – A solution is a homogeneous mixture. – Solvents dissolve other substances. – Solutes dissolve in a solvent. solution Connect: What are the solvent and solutes in a beverage you drink? 2.2 Properties of Water “Like dissolves like.” – Polar solvents dissolve polar solutes. – Nonpolar solvents dissolve nonpolar solutes. – Polar substances and nonpolar substances generally remain separate. Polar Ex: The liquid part of your Nonpolar Ex: blood, called Fats and oils plasma, is about rarely dissolve in 95% water. The water. Fats and solvent in plasma oils are nonpolar is water and all so they do not the dissolved have charged substances are regions so they the solutes: are not attracted sugars and to polar proteins etc.. molecules. 2.2 Properties of Water Some compounds form acids or bases. An acid releases a hydrogen ion when it dissolves in water. – high H+ concentration stomach acid pH between 1 and 3 – pH less than 7 more acidic 2.2 Properties of Water A base removes hydrogen ions from a solution. – low H+ concentration – pH greater than 7 bile pH between 8 and 9 more basic 2.2 Properties of Water A neutral solution has a pH of 7. pure water pH 7 Apply: Cells have higher H+ concentrations than blood. Which has a higher pH? Why? 2.2 Properties of Water Biology Connection and pH Most organism’s (including humans) need to keep their pH within a very small range (around 7). pH can be regulated by buffers, compounds that can bind to an H+ ion when the H+ concentration increases and can release H+ ions when the H+ concentration decreases. – Exceptions: A few organisms thrive in very acidic environments: azalea’s prefer soil around a 4.5 pH and microorganisms called Picrophilus survive best at extremely acidic pH (0.7). 2.2 Properties of Water pH indicators Indicators are chemicals that can be used to determine the pH of a substance. Ex: natural indicator = cabbage Ex: Litmus papers are indicators 2.2 Properties of Water SUMMARY Water is a molecule of life as it is essential for all the metabolic processes taking place in our body. A molecule of water is made up of one oxygen atom to which two hydrogen atoms are attached via covalent bonds making a bond angle of 104.5o. All water molecules are held together via strong hydrogen bonds among them. One water molecule can make a total of 4 hydrogen bonds. In its pure form, water is tasteless and odorless liquid that appears blue against a white background. Due to its polarity and its ability to form hydrogen, it acts as an excellent solvent for polar as well as ionic substances. This property makes water a universal solvent although it cannot dissolve non-polar substances. https://alevelbiology.co.uk/ 2.2 Properties of Water SUMMARY Because of strong hydrogen bonding, water has two very important properties; High specific heat capacity- the high heat capacity acts as a temperature stabilizer in living bodies. High heat of vaporization - the high heat of vaporization makes it a heat sink for living bodies providing cooling effect upon vaporization. Water also acts as an excellent lubricant providing a cushion effect to protect vital body organs. Water also acts as an ideal transport medium as well as reaction medium in living organisms. https://alevelbiology.co.uk/ 2.2 Properties of Water References https://alevelbiology.co.uk/ http://www.deercreekhs.org https://www.youtube.com/watch?v=3jwAGWky98c 2.2 Properties of Water ASYNCHRONOUS ACTIVITY 1. List down at least 3 application of hydrogen bonding in biological system. Show the bonding of hydrogen with other electronegative element. Importance of hydrogen Hydrogen bonding bonding to biological system 1. 2. 3. 2. List down the importance of water in the human body. Draw an arrow to pinpoint the part where water is needed. https://www.innerbody.com/