The Big WATER Power Point

1. The Big WATER Power Point

2. WATER FORMULA H2O

3. 3 atoms makes water TRI-ATOMIC

4. The polar bonds between oxygen and hydrogen in water are COVALENT. It is not ionicsince both oxygen andhydrogen are NON-METALS.

5. Water is always a BENT molecule. • It does not have Radial Symmetry, • It a POLAR MOLECULE dot diagram for water

6. Covalent Bonding To make a covalent bond in chemistry you need 2 electrons, one from each atom involved. A pair of electrons makes a single bond.

7. UNSHARED PAIRS OF ELECTRONS Oxygen has 6 valence electrons. One electron forms a bond with a hydrogen(a pair of electrons makes one bond).Another oxygen electron bonds with the other hydrogen (another pair of electrons makes another bond). That leaves 4 more oxygen electrons, which like to hang out in pairs. So, the oxygen in water has 2 pairs of unshared electrons.

8. These dipole arrows between oxygen and hydrogen, show that the valence electrons from H move to the oxygenatom, making the hydrogen more “positive”; and the oxygen more “negative”. The arrow heads point towhere the electrons go. The cross is a (+) sign,indicating where the electroncame from. The smiley face is just that, it has no bearing in chemistry that I know of.

9. Electronegativity difference between HYDROGEN and OXYGEN oxygen EN = 3.4 hydrogen EN = 2.2 difference = 1.2 = polar bond oxygen gets the electrons from hydrogen MOST OF THE TIME, because it has the HIGHER Electronegativity value on Table S. The greater the EN difference, the MORE POLAR THE BOND.

10. THE DIPOLE ARROWS INDICATE THE (–) and (+) sides of a bond THE BONDS ARE POLAR

11. Hydrogen Bonding is the bonding between different molecules, or inter-molecular bonds. It has NOTHING to do with bonds inside of a single molecule. The positive side of the molecule, the hydrogen side in water, is attracted to the negative side of another water molecule, the oxygen side. Hydrogen Bonding occurs only between DIFFERENT MOLECULES.

12. MOLAR MASSES Bigger molecules that are gases at STP includeoxygen, nitrogen, and fluorine. oxygen: 32 g/mole fluorine: 38 g/mole nitrogen: 28 g/molewater: 18 g/mole You might guess that water should be a gas at STP because it has such a lower molar mass, but it’s not. That’s because it has so manyINTERMOLECULARhydrogen bonds. Those are the bonds between water molecules due to the fantastic polarity the molecules have. They stick together + to – , very strongly.

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14. Water Properties Surface Tension is HIGH. Vapor Pressure is LOW (it won’t evaporate very well) Heat of Vaporization & BOILING POINT is HIGH. SOLID ICE IS LESS DENSE THAN LIQUID WATER.

15. HYDROGEN BONDING Surface Tension is HIGH.Due to hydrogen bonding keeping the surface of the water tightly bound together. There is no water to air bonding. Vapor Pressure is LOWDue to hydrogen bonding keeping the water is tightly bound together. The water does not want to let itself evaporate easily. Heat of Vaporization & BOILING POINT is HIGH. Due to hydrogen bonding keeping the surface of the water tightly bound together. It takes a lot of energy to heat up and boil the water, it is so attracted to itself that the energy required to break all of the hydrogen bonds is high. SOLID ICE IS LESS DENSE THAN LIQUID WATER. Due to hydrogen bonding keeping the water tightly bound together. The Hydrogen bonds force the water molecules into 6-sided (6 molecules) hexagonal shapes, that take up MORE ROOM than six molecules loose that can flow on each other. As a solid, these six molecules have a small but real space in the center, leaving the solid ice less dense than the liquid water. This is one of few substances that the solid floats in its own liquid.

16. If the question has anything to do with the PROPERTIES OF WATER, the answer is MOST LIKELY HYDROGEN BONDING.

17. Vapor Pressure & Boiling Point are alike, in that water leaves the liquid phase to enter the gas phase. The first is by evaporation & the other by high temps.

18. TABLE H Look NOW and see that at 180 kPa water boils at the temperature of 120°C (approximately) High air pressure increases the boiling point because the air pressure pushes down on the water as it boils, holding it together until more energythan usual is added.

19. Surface tension is caused by the attraction of water molecules to themselves by hydrogen bonding. The “tightness” of this bonding creates a strong “skin”which defines the edge of the water clearly from the air.

20. Surfactants interfere with the hydrogen bonding between water molecules (or other polar liquids) which disrupts the amount of inter molecular bonding. This lowers surface tension. If you put soap into water with water striders on it, the bugs “fall through” the surface of the water because the surface tension breaks down.

21. A neat example of hydrogen bonding in action, SURFACE TENSION of water, caused by the intermolecular attractiondue to hydrogen bonds.

22. The specific heat capacity of water is given in table B, it is 4.18 J/g·°CThese boys have nothing to do with chem

23. Eggs may cook on the metal man hole cover because the heat it absorbs will raise the temperature of the metal higher than that of the puddle. That’s because water has a high specific heat capacity and metals have a much lower specific heat capacity.

24. SOLUTIONS When water dissolves a compound, an solution is formed. An aqueous solution has water as the SOLVENT. What is dissolved into the water is called the SOLUTE. Saltwater has water as a solvent, and salt as the solute.

25. Density most solids are more dense than they were as liquids. They sink in their own liquid. Water is completely opposite of that, ice floats on water. Liquid water is MOST DENSE at 4ºC and solid ice is least dense of all water (in any phase).Ice floats on all water.

26. HONEYCOMB It’s a tasty breakfast cereal and it accurately describes how water molecules of ice are arranged. This structure makes this arrangement larger per mass than the liquid, therefore ice floats because it’s less dense than water.

27. See the 6 water models, with dotted lines showing Hydrogen bonding between the molecules. When the kinetic energy is low enough (cold enough) the molecules slow down enough that the hydrogen bonding is then strong enough to “lock” the molecles into these hexagonal lattices. Sometimes smaller or larger groupings of molecules is possible, this is normal.

28. To melt 10.0 g of ice you use the formulaq = mHf q = (10.0 g)(334 J/g) = 3340 J To heat 10.0 grams of water from 10.0°Cto 75.0°C you use the other formulaq = mC∆T q = (10.0 g)(4.18J/g·°C)(65.0 °C) = 2720 J Here is MATHEMATICAL PROOF that melting 10.0 grams of ice takes more heat than to warm 10.0 grams of water up by 65 °C

29. Pure Water? In nature, pure water does not exist because too many things can dissolve into it. Some things are pollution, others are just normal stuff likeminerals and salts, etc.

30. Aqueous Solutions are solutions with water as a solvent. Solvent: something that the solute mixes into, such as water, or another liquid. Solute: what mixes into the solvent, for example, in a soda pop, sugar is a solute dissolved into the solvent water. SWEAT is actually an aqueous sodium chloride solution. It tastes salty too.

31. Like Dissolves Like This means that POLAR SOLVENTS, such as WATER, can dissolve POLAR solutes, like salts, HCl, or chloroform CHCl3. Non Polar Solvents can dissolve Non Polar solutes, such as carbon tetrachloride (the solute) dissolving into gasoline (the solvent) Oil does not mix with water, oil is non polar but water is.

32. Oil does not mix with vinegar (HC2H3O2 in H2O). Oil is a NONPOLAR liquid. Water and vinegar are polar.LIKE DISSOLVES LIKE. Oil Vinegar

33. Miscible and Immiscible Miscible and immiscible are vocabulary words youwill NEED to remember. MISCIBLE: means that 2 liquids can dissolve into each other, such as water and alcohol (both polar) have this trait together. IMMISCIBLE: means that 2 liquids cannot dissolve into each other, for example: oil and vinegar, oil and water, gasoline and water.

34. CoCl2 • 6H2O Hydrates are ionic compounds with water associated with them- like copper (II) sulfate pentahydrate. What is the name of this compound? What is the molar mass of this compound? Don’t just jump ahead, the answer is not as important, as being able to get the answer!

35. Find the Molar Mass CoCl2 • 6H2O has a molar mass of Co + Cl + Cl + 6 water moleculesor 59 g + 35 g + 35 g + 108 g = 257 g/mole The molar mass of this hydrate is 257 grams /mole And its name… Cobalt (II) chloride hexahydrate

36. How much water is in CoCl2 • 6H2Oby mass? The % by mass of water for this compound is found this way: % comp by mass = % comp by mass of water in this hydrate is = 108 g 257 g Mass of the partMass of the whole X 100% X 100% = 42.0% water

37. Consider making your academic life better, start reading chapter 17 on Water.