- 1. Vital Water Alice NewtonUniversity of Algarve Joint Master in Water and Coastal Management University of Bergen 2005-2006
- Philip Ball 1999:H 2 O A biography of Water ISBN 0 75381 092 1
- Peter H. Gleick 1993:Water in CrisisOxford University Press
- Open University course team 1997 : Seawater: its composition, properties and behaviour
- Frank J. Millero 1996 : Chemical Oceanography, CRC Press
3. Bibliography 2
- United Nations Environment Program www.unep.org Vital Water Graphics
- Global International Water Assessment www.giwa.net
- Intergovernemntal Panel on Climate Change www.IPCC.org
- Vital water is an introductory lecture that relatesboth to integrated river basin management or integrated coastal zone management
- It also links up with many other modules in the course
- No special skills are required for this lecture
- A knowledge of basic inorganic and environmental chemistry is useful.
- The constituents of water
- Composition of natural waters
- Water and society, resources, uses and abuses
7. Learning outcomes
- After completing this module you should know:that although water is a very common substance on Earth, it has strange properties and is a scarce resource
- After completing this module you should be able to:Explain why water is so special and what some consequences are for water and coastal management
8. Other skills
- Consult scientific literature and websites
9. The Constituents of Watera little chemistry
- H 2 O is the basic unit of water
- Ratio 2:1 is a consequence of the atomic structure
- About of the mass of the Universe is Hydrogen!
- H usually has no neutrons, so the atomic mass is 1
- 0.000015 % of H has 1 neutron, so atomic mass is 2 (1 proton + 1 neutron)
- This isotope (different number of neutrons) is called heavy water, Deuterium, or Hydrogen-2
- Mass of O is about 16 x mass of H (different isotopes and neutons)
- O can have 7,8 , 9 or 10 neutrons
- O is the third most abundant element in the Universe
- (the second most abundant element in the Universe is Helium, relatively unreactive)
12. The Origin of H and Oa little cosmo-chemistry
- Protons (H + ) formed a millionth of a second after Big Bang,T~ a trillion degrees
- Nucleosynthesis started one hundredth of a second later (protons+neutrons),T~ three billion degrees
- Hydrogen atoms form, T~ 4000 C
13. The Origin of H, O and Water
- Gravity leads to formation of Galaxies and StarsHans Bethe 1939
- Elements (C-N- O) formed in stars byfusion
- Mainly generates15 O but also16 O17 OBurbridge,Burbridge, Fowler and Hoyle 1957
- Water formed byreactionof H and O
14. From Element to compound
- Water classically was thought of as an Element
- Lavoisiers experiments 1784 prove that water is formed by burning Hydrogen in the presence of oxygen. Hydrogen means water former
- Nicholson and Carlisle split water by electrolysis to form hydrogen and oxygen
- Berzelius recognized the fixed ratios H=2, O=1
15. Wateras a Liquid 16. Liquid water
- At present most of the water on Earth is in the liquid phase
- Most liquid water (~97%) is in seawater
- Water is the main component (~96%) of seawater
17. The Water Molecule
- Hydrogen (H) and Oxygen (O)
- H 2 O is the basic unit of water
- Consequence ofatomicand molecularstructure
18. Molecular Structure of Water
- Hydrogen atoms havea partial positive charge.
- Oxygen has 2 unbondedpairs of electrons withpartial negative charges.
- Tetrahedral, distorted by charges to minimize repulsion
- Molecular structure is "bent" to yield a104.5angle between the hydrogen atoms instead of 109.5 for a regular tetrahedron .
19. Hydrogen bonds
- A partly positive hydrogen atom of one water molecule attracts the partly negative unbonded electron pair in the oxygen atom, forming a hydrogen bond.
20. Hydrogen bonds
- The oxygen atom of a water molecule is the hydrogen bond acceptor for two hydrogen atoms .
- Each O-H group serves as a hydrogen bond donor.
21. 4 Hydrogen bonds
- Leads to the formationof4 hydrogen bonds by water
- The tetrahedral structureof the water hydrogen bondsis a consequence of the sp3hybridization of theoxygen's electrons.
- The two hydrogen bonds between the oxygen and the hydrogen atoms on another water molecule utilize the two partly-negative pairs of unbonded electrons on oxygen.
22. Structure of liquid water
- The hydrogen bonding pattern of water is more irregular than that of ice.
- The absolute structure of liquid waterhas not been determined .
- Many theoriese.g.Frank and Wenflickering cluster model : as a liquid, water has partly crystalline clusters but some loose molecules
23. Properties of Water The Strange Liquid 24. Density anomaly
- Most substances are denser in the solid than in the liquid phase
- The structure of ice at 0 o C is less dense than that of liquid water at 0 o Cbecause ice has a more rigid lattice.
- Ice forms at surface and floats
- Enormous implications for climate
25. High SpecificHeat Capacity
- Very high energy required tochange the temperatureof water
- Water is slow to heat and slow to cool
- Warm ocean currents can therefore transport huge amounts of heat
- Gulf Stream transports more heat daily than would be produced by burning global quantity of coal mined annually
26. Latent Heat Capacity
- Energy tochange phasewithout changing temperature
- When water isheated to 100C, is doesnt all instantly evaporate to steam. A lot of heat has to be supplied to transform all the liquid into vapour.
- When ice isreaches 0C, is doesnt all instantly melt. A lot more heat must be applied to transform all the ice into liquid water
27. Specific HeatandLatent Heat Heat Energy Supplied 100 C 0 C T C Boiling Point Freezing Point Specific Heat of Water Specific Heat of Ice Latent Heat ofWater LatentHeatof Ice 28. Phase transitions solid-liquid-gas
- Boundaries ofphasesare controlled by temperature and pressure
- Phase diagramplots phases on a graph of temperature and pressure
T P 29. Phase diagram of water 30. Triple Point
- Solid, Liquid andGas phasescan co-exist
- BelowTriple Point , solidsublimesto gas
- Gas and Solid extend throughout T and P
- Liquid is a contigent state, not always necessary
- Boundarybetween Liquidand Solid stops atCritical Point
- Supercritical region: gas and liquid behave in same way
- Gas and Liquid are bothFluids phases
32. More anomalous properties
- Excellentsolvent , especially of ionic compounds
- Highlyreactiveand therefore corrosive
- Viscosity increases with pressure
- High boiling point and freezing point
- Low dissociation, but can act as an Acid or Alkali and is an electrolyte
33. Water as Ice 34. Molecular structure of ice
- Water molecules in ice form an open hexagonal lattice in which every water molecule is hydrogen bonded to four others.
- The geometric regularity of these hydrogen bonds contributes to the strength of the ice crystal.
- All hydrogen bonds are satisfied in ice.
Structure of Ice I normal ice 35. Normal ice
- Ice I hashexagonal symmetrythat we associate with snowflakes
- Dendritic( branching ) growth from a seed particle
36. Many types of ice
- Under pressure, Ice I can change to other formse.g.ice II andice III.
- 1998 Ice XII was discovered!
- Some forms are very unsta