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Ch 15/16 Water and its Properties

Ch 15/16 Water and its Properties. 1mL = 0.001L. Vocabulary (tested-star these terms) • solute, solvent, pressure • temperature, agitation, concentration • saturated, unsaturated, % composition *** Molarity ***.

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Ch 15/16 Water and its Properties

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  1. Ch 15/16 Water and its Properties

  2. 1mL = 0.001L • Vocabulary (tested-star these terms) • • solute, solvent, pressure• temperature, agitation, concentration• saturated, unsaturated, % composition • *** Molarity ***

  3. Surface tension – hydrogen bonds create an inward pull that minimizes surface area. Mr. B:: Creates a solid shell on top of water that can support light weight items (small bugs, pepper flakes). Createsraindrops.

  4. Hydrogen bonds between water molecules. All atoms like to have 8 electrons in valance shell (2 s and 6 p’s.) They are in 4 pairs of two. 2 pairs grab H. 2 pairs grab other H20 molecules. Discuss Ice in rivers and circle of life. Show water / oil bottles with 2 dyes

  5. Aqueous solution – water w/ dissolved particles (aq)Solvent – water (dissolver)Solute – salt (dissolvee)(NEW WORD?)

  6. Surfactants • Stop or break down the hydrogen bonding • Teacher Notes and You tube Video link: • http://www.youtube.com/watch?v=hKoB0MHVBvM • When you pair carbonated soda and Mentos candies, you can create an overflow of fun. Perform your experiments outside, in an open area, and use protective eye gear. The nature of the reaction between the soda and candy is a matter of debate among scientists. The effect may be due to a physical or chemical cause. Most believe that ingredients in the candies cause a break in surface tension in the liquid, allowing new bubbles to more easily form, while carbon dioxide bubbles form well on the pitted surface of the candiesRead more: Mentos and Soda Experiments | eHow.comhttp://www.ehow.com/list_7487590_mentos-soda-experiments.html#ixzz2Ow8u7tmr

  7. Solvation: a solute dissolves or dissociates into ions(happens with most soluble ionic compounds and acids)Electrolyte: will conduct electricity when dissolved in a liquid.3 ways to speed up solvationHeatingStirringIncreasing surface area of the solute (powder)

  8. A solution does not have to contain a liquidAir is a solution 78% nitrogen 14karat gold is a solution58% gold 42% Copper

  9. Solid Hydrate:A crystal with big spaces that water can easily move into.Demo: Na2SO4•10H2O(s)Show crystal model of Na2SO4 Add some H2O models to it.

  10. Solid Hydrate

  11. HydratesCuSO4•5H2O(s)1 (CuSO4) to 5 ( H2O) ratioIn this solid compound there are 5 water molecules for every one CuSO4.

  12. What is the molar mass of the hydrate?Add the molar mass of CuSO4 and 5 water molecules. CuSO4•5H2O(s) Cu S O4• 5H2O(s)

  13. CuSO4•5H2O(s)What is percent H2O?

  14. Percent H2O Hydrate:CuSO4•5H2O(s)What is percent H2O?

  15. What is the molar mass of Na2SO4•10H2O(s)

  16. What is the molar mass of Na2SO4•10H2O(s)

  17. What is the percent water in this hydrate? Na2SO4•10H2O(s)

  18. What is the percent water in this hydrate? Na2SO4•10H2O(s)

  19. What is the percent water in this hydrate? Na2SO4•10H2O(s)

  20. What is the percent water in this hydrate? Na2SO4•10H2O(s) What is the correct sig fig in the answer: 56%

  21. What is the percent sodium in this hydrate? Na2SO4•10H2O(s) WOD: % Chem = Mass Chem x 100% Total Mass

  22. What is the percent sodium in this hydrate? Na2SO4•10H2O(s) What is the correct sig fig in the answer: 14%

  23. How many grams of water are in a 34g sample of Na2SO4•10H2O(s)?

  24. How many grams of water are in a 34g sample of Na2SO4•10H2O(s)? 56% x 34g = 19g H20

  25. Solubility – g of solute per 100g of solvent at a certain temperatureBelow: 2 different liquids, same amount of solute (dye). Note black bars.

  26. Does solubility change with temperature?

  27. Does solubility change with temperature?

  28. saturated solution- will dissolve no more solute (at that temperature). Excess usually makes a pile of crystals on the bottom.unsaturated solution – will dissolve more solute (at that temperature)(left 3 beakers on next slide)

  29. Dilute vs concentrated As you add more solute, from left to right  Dilute More Concentrated Saturated Saturated Since 3 on right are saturated, keep adding solute, but they don’t get darker. No more dissolves into them.

  30. Supersaturated solution – contains more solute then should be dissolved at a temperatureex…heating then cooling a solution

  31. Supersatured videos http://www.youtube.com/watch?v=XSGvy2FPfCw http://www.youtube.com/watch?v=HnSg2cl09PI 3 min Long one if you have extra time: http://www.youtube.com/watch?v=1y3bKIOkcmk

  32. New Subject: Gas Solubility: S1 = S2 P1 P2 Called Henry’s Law. Amount of gas dissolved in a liquid. Solubility of a gas in a liquid is directly related to pressure.

  33. Miscible – liquids dissolve in each other. (liquids that can mix together)Immiscible – Guess?Is this lava lamp miscible or immiscible?

  34. 16.2 Molarity Pg 526Molarity tells us the number of moles of solute in exactly 1 liter of a solution.M = mol ÷ L (of solution)

  35. Do not confuse lower case m (Molality) and Capitol M (Molarity)Molality: m = moles of SolutePg 538 kg of solventConcentrations(Notice Case of M or m)M = Molarity = Volume basedm = Molality = Mass based

  36. Molarity: M = mol ÷ L (of solution) molality: m = moles of Solute Pg 538 kg of solventConcentrations (Note case of M / m) Molarity: M = Volume based of SOLUTION! (after mix) molality: m = Mass based of SOLVENT! (before mix)Solute + Solvent = Solution

  37. We need two pieces of information to calculate the molarity of a solute in a solution: The moles of solute present in the solution. The volume of (final) solution (in liters) containing the solute.

  38. What is the molarity of a 125mL solution with 12.5g of NaCl dissolved in it?

  39. What is the molarity of a 125mL solution with 12.5g of NaCl dissolved in it? Do we have moles and liters?

  40. What is the molarity of a 125mL solution with 12.5g of NaCl dissolved in it?

  41. What is the molarity of a 125mL solution with 12.5g of NaCl dissolved in it?

  42. What is the molarity of a 125mL solution with 12.5g of NaCl dissolved in it?

  43. What is the molarity of a 125mL solution with 12.5g of NaCl dissolved in it?

  44. How many liters of 18.1M HCl are needed to obtain 2.55 mol?

  45. How many liters of 18.1M HCl are needed to obtain 2.55 mol?

  46. Quiz 16.2A 137g sample of BaCl2.5H2O is dried in an oven. 1a) How many grams of water will be driven off?1b) How many grams of BaCl2 will remain?2. What would the molarity of a solution be if the above 137g sample of BaCl2.5H2O was instead dissolved to make a 0.75L solution?

  47. Answers Quiz 16.2A 137g sample of BaCl2.5H2O is dried in an oven. 1a) How many grams of water will be driven off?1b) How many grams of BaCl2 will remain?

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