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BELL WORK 3-10-14

BELL WORK 3-10-14. What is a chemical solution? Try to explain it as if to a 5 th grader, be as “scientific” as possible!. Homework Packet Turn-In. Pressure Conversions-ppt. 1-6 White review—Boyles’ 1-4 White review Charles’ 5-8 White review Combined 9-13 White Review Mixed 14-20

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BELL WORK 3-10-14

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  1. BELL WORK 3-10-14 What is a chemical solution? Try to explain it as if to a 5th grader, be as “scientific” as possible!

  2. Homework Packet Turn-In • Pressure Conversions-ppt. 1-6 • White review—Boyles’ 1-4 • White review Charles’ 5-8 • White review Combined 9-13 • White Review Mixed 14-20 • Ideal and Combined (white sheet) 1-19 odds. • Gas Stoichiometry (white sheet) 1-4, 5-10.

  3. 10 March 2014 Objective: You will KNOW the parts of a solution, UNDERSTAND how to calculate molarity, and tommorow APPLY your knowledge to making solutions Agenda: Solutions Solubility Molarity

  4. Concentration and Reaction Rates Video http://www.youtube.com/watch?v=kjKyEdrVXJA

  5. A solution is formed when a ____________ and _____________are mixed. Solvent Solute Some Definitions

  6. PARTS OF SOLUTIONS SOLUTE–what’s being dissolved (usually the lesser amount) SOLVENT–what’s dissolving the solute (usually the greater amount) Solute + Solvent = Solution

  7. Definitions Solutions can be saturated or unsaturated. __________solution contain the maximum amount of solute. An __________solution contains less solute than a solvent can hold at a particular temp. Saturated unsaturated

  8. Definitions SUPERSATURATED SOLUTIONScontain more solute than a solvent can hold They are unstable. The super saturation is only temporary, and usually accomplished in one of two ways:

  9. To Make a Supersaturated Solution • Warm the solvent so that it will dissolve more, then cool the solution • Evaporate some of the solvent carefully so that the solute does not solidify and come out of solution.

  10. Supersaturated Rock Candy This supersaturated sucrose and food coloring solution uses a “seed” crystal to make… Crystal Rock candy

  11. 1. _______ increases solubility in most liquids * solubility of_________ are greater in cold water than hot. 2. ________ the solubility of gas increases w/ increasing pressure Factors affecting solubility—dissolve Heat gases True:

  12. Polarity Review • http://www.youtube.com/watch?v=PVL24HAesnc

  13. 3. __________ molecules will only dissolve in _________ molecules Non- polar molecules will only dissolve in non-polar molecules “_________dissolves__________” Factors affecting solubility Polar Polar like like

  14. Polarity Recall "polar" molecules: An uneven distribution of electron density. Ex. water H2O “non polar” molecules: an even distribution of electron density. Ex. Oil, propane, etc.

  15. Question A solution is made up of 25 grams of cyclohexane (non-polar) and 7 grams of acetonitrile (polar). What is the solute ? What is the solvent? Would you expect the solvent to readily mix with the solute?

  16. With your neighbor Mr. Brunenkant tried to mix 1-butanol (non-polar) with cyclohexane (non-polar) to make a solvent that would clean a water soluble crystal residue on his desk. 1. Will the two solvents mix readily? 2. Do you think the solvent mixture would dissolve the water soluble crystals? Why or why not?

  17. moles solute ( M ) = Molarity liters of solution Concentration of a solution The amount of solute in a solution is given by its concentration. M = mol L

  18. Less than 1.0 L of water was used to make 1.0 L of solution. Why?

  19. Practice Dissolve 5.00 g of NiCl2 in enough water to make 250 mL of solution. Calculate the Molarity.

  20. Dissolve 5.00 g of NiCl2 in enough water to make 250 mL of solution. Calculate the Molarity. Step 1: Calc. moles of NiCl2 Step 2: Calculate Molarity [NiCl2] = 0.155 M

  21. What amount (grams) of NiCl2is needed to make a 0.1M solution at a volume of 100ml? Step 1: Calc. moles of NiCl2in 100ml 0.1M sol. 0.01moles 0.100L x 0.1mol/L = Step 2: Calculate grams 0.01mol x 129g/mol = 1.29grams

  22. What amount (grams) of NaClis needed to make a 0.5M solution at a volume of 500ml? Step 1: Calc. moles of NaClin 500ml 0.5M sol. 0.25moles 0.500L x 0.5mol/L = Step 2: Calculate grams 0.25mol x 58g/mol = 14.5grams

  23. Closure Write down your answer: • What is a chemical solution? • What is a solute? • What is a solvent?

  24. Homework • What is the molarity of 7 g of NaCl in 300 mL of water? • What is the molarity of 12 g of KBr in 700 mL of water? • If you have a 0.7 molar NaCl solution, how many moles of NaCl are there in 1200 mL? • Based on your answer from #3, how many grams would that be?

  25. BW 3-12-13 • What is the molarity if you have 3.7 moles and 2.1 L? • If you dissolve 10.00 g of CaCl2 in enough water to make 500 mL of solution, what is the Molarity?

  26. 12 March 2013 Objective: You will understand molarity and how to calculate it. Agenda: Molarity Practice

  27. Using Molarity What mass of oxalic acid, H2C2O4, is required to make 250. mL of a 0.0500 M solution? moles = M•V

  28. Using Molarity What mass of oxalic acid, H2C2O4, is required to make 250. mL of a 0.05 M solution? Step 1: mL L. 250 mL x 1L/1000mL = 0.250 L Step 2: Calculate. Mol=(0.05 mol/L) (0.250 L) = 0.0125 mol Step 3: Convert moles  grams. (0.0125 mol)(90.00 g/mol) = 1.13 g moles = M•V

  29. Practice How many grams of NaOH are required to prepare 400 mL of 3.0M NaOH solution? 1) 12 g 2) 48 g 3) 300 g

  30. Practice makes Perfect Calculate the molarity when 75.0 grams of MgCl2 is dissolved in 500.0 mL of solution. 100.0 grams of sucrose (C12H22O11)is dissolved in 1.50 L of solution. What is the molarity?

  31. Molarity Pre-lab time! • Get a sheet of paper out and title it: Determining Molarity Lab

  32. HW: Problems 1-11 odds

  33. BELL WORK 3-13-13 What is the molarity of a solution with 6.2 grams of HNO4 dissolved in 350ml of water? If molarity of HNO4 is.090 M and you have 5 liters, how many moles is that? Grams?

  34. Happy Pi Day!BELL WORK 3-14-13 • 49.8 grams of KI is dissolved in enough water to make 3.14 L of solution. What is the molarity? • What makes up a solution? • How do you increase solubility? • What type of substance does a polar substance dissolve in?

  35. Bell Work 3/15/2013 • What is the molarity of a solution if it has 7 moles of HCl and there are 2.1 L of solution? • How many grams of KBr must you weigh out in order to make 500 mL of a 3M solution?

  36. 15 March 2013 Objective: you will understand how to use the dilutions formula and apply it in a laboratory setting Agenda: Dilutions “Killer Kool Aid Lab”--Friday

  37. DILUTION Going from one concentration to another M1V1=M2V2 M = molarity (mol/L) V = volume (what unit ????) Starting/ what you have M1 and V1 Ending/ what you want M2 and V2

  38. 4.5

  39. Moles of solute before dilution (i) Moles of solute after dilution (f) = Dilution Add Solvent = M2V2 M1V1 Dilutionis the procedure for preparing a less concentrated solution from a more concentrated solution. 4.5

  40. M2V2 0.200 x 0.06 V1 = = 4.00 M1 How would you prepare 60.0 mL of 0.2M HNO3 from a stock solution of 4.00 M HNO3? M1V1 = M2V2 M1 = 4.00 M2 = 0.200 V2 = 0.06 L V1 = ? L = 0.003 L = 3 mL + 57 mL of water 3 mL of acid = 60 mL of solution

  41. DILUTION What would the new molarity be of a 250ml 0.8M solution of HCl if it was diluted to 450ml?

  42. Practice What is the molarity of a solution with 2.0 grams of NaOH dissolved in 300ml of water. What would be the new molarity if you diluted to solution of 630ml?

  43. Bellwork 3-18-13 How many moles of KNO3 are needed to create 500 mL of 6.0M solution of KNO3?

  44. Lab Time Killer Kool Aid!!!

  45. Lab Time Killer Kool Aid!!! So, group 1 does dilutions for Red 2.2M 0.176, Blue 1.50M 0.135M, Green 3.60M  0.324M.

  46. Preparing Solutions Weigh out a solid solute and dissolve in a given quantity of solvent. Dilute a concentrated solution to give one that is less concentrated.

  47. Titrations In a titration a solution of accurately known concentration is added gradually added to another solution of unknown concentration until the chemical reaction between the two solutions is complete. Equivalence pointthe point at which the reaction is complete Indicator– substance that changes color at (or near) the equivalence point Slowly add base to unknown acid UNTIL the indicator changes color

  48. Oxalic acid, H2C2O4 Acid Base Rxn Titration H2C2O4 (aq) + 2NaOH (aq)Na2C2O4 (aq) + 2H2O (l) acidbase Carry out this reaction using a TITRATION.

  49. Setup for titrating an acid w/ a base

  50. Titration 1. Add solution from the buret. 2. Reagent (base) reacts with compound (acid) in solution in the flask. • Indicator shows when exact stoichiometric reaction has occurred. (Acid = Base) This is called NEUTRALIZATION.

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