Oceanography 5 - Properties of Water

13 pages
69 views

Please download to get full document.

View again

of 13
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Share
Description
MOLECULAR STRUCTURE OF WATER PHYSICAL AND CHEMICAL PROPERTIES OF SEAWATER H2O Two atoms of hydrogen (one proton +, one electron -) One atom of oxygen (8 protons +, 8 electrons -) They are joined by COVALENT BONDS (the oxygen and hydrogen share electrons) MOLECULAR STRUCTURE OF WATER Both hydrogen atoms are on one side of the water molecule The molecule’s electrons are clustered on the opposite side of the molecule This gives the water molecule POLARITY i.e. one side has a slight positive cha
Tags
Transcript
  1 PHYSICAL AND CHEMICALPROPERTIES OF SEAWATER MOLECULAR STRUCTURE OF WATER  H 2 O Two atoms of hydrogen (one proton +, one electron -) One atom of oxygen (8 protons +, 8 electrons -) They are joined by COVALENT BONDS (the oxygen and hydrogen share electrons) MOLECULAR STRUCTURE OF WATER  Both hydrogen atoms are on one side of thewater moleculeThe molecule’s electrons are clustered on theopposite side of the moleculeThis gives the water molecule POLARITYi.e. one side has a slight positive charge and oneside a slight negative charge = DIPOLAR e.g. like a flashlight battery or bar magnet HYDROGEN BONDS The positive side of the molecule is attractedto negative charges,e.g. the opposite sides of other watermoleculesThe attraction forms a weak bond =HYDROGEN BONDNB A hydrogen bond is much weaker than athe bond between atoms (covalent bond)  2 HYDROGEN BONDS Hydrogen bonds help give water some of itspropertiesIncluding –SURFACE TENSION…the “skin” on glass of water or a pondCOHESION….molecules pulling together to form dropletsCAPILARITYThe ability to pull molecules behind it up anarrow tube (capillary) e.g. the xylem of plants Surface TensionCapillarity THE UNIVERSAL SOLVENT Water molecules not only stick to other watermolecules, but also other polar substancese.g. Atoms in salt (NaCl) molecules are heldtogether by IONIC BONDSPositive Na + is strongly attracted to negative Cl - = ELECTROSTATIC ATTRACTIONWhen NaClis put in water the attractionbetween Na + and Cl - is reduced (80 times) → Na + and Cl - become separatedand the salt crystals dissolve  3 THE UNIVERSAL SOLVENT The process by which water moleculessurround ions (positively or negatively charged particles) = HYDRATIONBecause water molecules not only interact withother molecules, but also with polar substanceswater can dissolve almost anything= THE UNIVERSAL SOLVENTIf water cannot dissolve a substance it isbecause it is not polar (e.g. oil) THERMAL PROPERTIES OF WATER  Water, like other matter, can exist in threestates: SOLID, LIQUID or GASWhat need to happen to change the state of asubstance?Bonds between molecules must be brokenThis requires that molecules move faster andmove further apartThis requires ENERGYBonds between molecules includeVAN DER WAAL’S FORCESWeak forces of attraction, but can be importantwhen molecules are close together (e.g. solid)In water –also Hydrogen Bonds THERMAL PROPERTIES OF WATERTHERMAL PROPERTIES OF WATER  The amount of energy needed to raise thetemperature of water by 1 o C= THE SPECIFIC HEAT CAPACITYThe SHC of water is very high – it takes more energy to increase the energy of hydrogen—bonded water molecules thanmolecules just kept together by Van DerWaal’sforces THERMAL PROPERTIES OF WATER  Therefore water can absorb a lot of heat before itstemperature rises.Also a lot of energy has to be released to causewater to coolThis means that water temperatures change moreslowly compared to the land -for examplee.g. California -sea water: 6.3 o C –20 o Cland: 3.6 o C –45.7 o CSOLID:When water is solid (i.e. ICE) water has a rigid,regular structure (crystalline) and moleculesare locked in placeLIQUID:Most common state of water. Molecules movefreely about, but still interact with each other(some bonds)GAS:Water molecules do not interact with each otherexcept during random collisions and movefreely THERMAL PROPERTIES OF WATER   4 If enough energy is added to water, bondsbreak and it becomes liquid( @ MELTING POINT) [0 o C; 34 o F] If enough energy is then addedit turns into gas ( @ BOILING POINT) [ 1 00 o C; 2 1 2 o F] If energy is removed the gas reverts back intoliquid ( @ CONDENSATION POINT)And more energy removes turns into a solid( @ FREEZING POINT) THERMAL PROPERTIES OF WATER  The heat energy needed to turn 1 g of asubstance at the melting point temperaturefrom solid to liquid=THE LATENT HEAT OF MELTING (i.e. the energy require to break bonds) The heat energy needed to turn 1 g of asubstance at the boiling point temperatureliquid to gas=THE LATENT HEAT OF VAPOURIZATION LATENT HEATSLATENT HEATS The heat energy needed to BE REMOVED to turn 1 g of a substance at the boiling point temperaturefrom gas to liquid=THE LATENT HEAT OF CONDENSATION (i.e. the energy required be removed to slow moleculesdown and to allow bonds to reform)The heat energy needed to BE REMOVED to turn 1 g of asubstance at the melting point temperature from liquid tosolid= THE LATENT HEAT OF FREEZING / FUSION
Related Search
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks
SAVE OUR EARTH

We need your sign to support Project to invent "SMART AND CONTROLLABLE REFLECTIVE BALLOONS" to cover the Sun and Save Our Earth.

More details...

Sign Now!

We are very appreciated for your Prompt Action!

x