General Chemistry 2 - Lesson 1.4: Water Structure & Properties PDF

Lesson 1.4 The Structure and Unique Properties of Water General Chemistry 2 1/2 Science, Technology, Engineering, and Mathematics  Have you ever thought about why researchers keep looking for traces of water on other planets?...

Lesson 1.4 The Structure and Unique Properties of Water General Chemistry 2 1/2 Science, Technology, Engineering, and Mathematics  Have you ever thought about why researchers keep looking for traces of water on other planets? 2 This is mainly because water is essential to life. All life on earth depends on water. 3 We, as humans, use water for drinking, cooking, cleaning and making other substances. 4 If a planet has liquid water in it, then there is a chance that life, similar to Earth, may exist. 5 5 Water Facts na…. Water makes up a large proportion of the entire biosphere and of these, 95% is saltwater and the remaining 5% is freshwater. 6 Water Facts na…. Water is locked up in ice and glaciers, deep and shallow underground lakes, soil, atmosphere, and in the rivers. 7 Water Facts na…. The human body consists of 70% water. 8 Water Percentage in Human Organs https://svalbardi.com/blogs/water/percentage 9 Water Percentage in Human Organs https://svalbardi.com/blogs/water/percentage 10 Total Body Water Percentage in Animals https://svalbardi.com/blogs/water/percentage 11 Water Facts na…. Water serves important purposes for life on Earth. Water’s unique properties result from the strong intermolecular forces of attraction characterized by hydrogen bonds. 12 What are the unique and important properties of water that make it suitable for life? 13 Learning Competency At the end of the lesson, you should be able to do the following: Explain the properties of water with its molecular structure and intermolecular forces (STEM_GC11IMF-IIIa-c-103). 14 What is the molecular shape of water? 15 The Structure of Water Water is represented by the chemical formula H2O. Lewis structure of water 16  The Structure of Water There are 4 electron domains around the central atom, O. Lone Pairs or Non-bonding Pairs -valence electrons that are not shared with another atom Lewis structure of water 17  The Structure of Water The electron domain geometry of water is tetrahedral. *4 electron domains -2 lone pairs on O -bonded to 2 H atoms 18 The Structure of Water Since there are two lone pairs present, the molecular geometry becomes bent. 19  The Structure of Water Since oxygen is more electronegative than hydrogen, then the dipole moment moves towards the oxygen atom. dipole moment of water 20  The Structure of Water The dipole moments do not cancel out. This means that the water molecule is polar. Polar Covalent Bond -the bonding electrons are shared unequally between atoms; there are partial charges. 21 Remember four (4) electron Water has _____________ domains around the central atom (O). It has two single bonds and two (2) lone pairs. _____________ Its electron domain geometry is tetrahedral and its molecular __________________ bent geometry is ___________________. 22 Remember 23 What intermolecular forces are present in water? 24  IMFAs Present in Water Water is an electrically neutral molecule. It exhibits the following intermolecular forces: London dispersion forces; dipole-dipole interactions; and hydrogen bonding. 25 Much of the unique properties of water are owed to the hydrogen bonding capacity of water. 26 What are the unique properties of water? 27  Properties of Water Physical Properties of Water Property Values specific heat capacity (liquid water) 4.18 J/g · ºC specific heat capacity (water vapor) 2.11 J/g · ºC specific heat capacity (ice) 2.00 J/g · ºC melting point 0 ºC boiling point 100 ºC 28  Properties of Water 1) Water has high boiling point due to H-bonds. 29 Properties of Water This also explains why water is liquid at room temperature in contrast to NH3, H2F, and HF which are all corosive gases at room temperature. 30  Properties of Water 2) Water has high specific heat. Specific heat is the amount of heat needed to change the temperature of 1 gram of a substance by 1°C. 31  Properties of Water The specific heat of water is 1 cal/g °C. It means that water can absorb or release large quantities of heat without change in temperature. 32  Properties of Water This is the reason why body temperature remains at 37°C even when there’s a change in the area’s temperature. 33  Properties of Water This also explains why oceans and lakes exert an influence on the climate. If there were no large bodies of water that surround the earth, the planet would experience great temperature variations. 34  Properties of Water 3) Water has high density in its liquid form. Solid water is less dense, and floats on liquid water. When solid water forms, the hydrogen bonds result in a very open structure with unoccupied spaces, causing the solid to occupy a larger volume than the liquid. This makes ice less dense than liquid water, causing ice to float on water. 35 When liquid water solidifies to ice, it arranges itself based on the hydrogen bonding requirements. 36 Properties of Water 37 Challenge Yourself How can you relate this property of water to the survival of aquatic organisms in temperate and polar countries? 38 Challenge Yourself Antarctic Icefish (Chaenocephalus aceratus) 39  Properties of Water 4) Water has high surface tension. This is because hydrogen bonds among water molecules resist stretching or breaking the surface. 40  Properties of Water 5) Water has high heat of vaporization. Large amount of heat is needed to vaporize a given amount of water. This causes a significant drop in temperature during evaporation. This explains why perspiration lowers the body temperature. 41  Properties of Water 6) Water is a good solvent. It has the ability to dissolve a large variety of chemical substances. ▪ salts and other ionic compounds ▪ polar covalent compounds such as alcohol and organic substances ▪ gases like oxygen and carbon dioxide 42 Challenge Yourself How can you relate this property of water to the role of water in plant nutrition? 43 Challenge Yourself 44 Challenge Yourself How can you relate this property of water to the issues on pollution? 45 Challenge Yourself 46