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TOPIC: intro to solutions and Concentration Do Now:

TOPIC: intro to solutions and Concentration Do Now:. Matter. Pure Substanc es. Mixtures. Elements. Compounds. Homogeneous Mixtures. Heterogeneous Mixtures. Classification of Matter. VIDEO. Heterogeneous Mixtures. See visibly different regions Granite Dirt Cereals Oil & Vinegar

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TOPIC: intro to solutions and Concentration Do Now:

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  1. TOPIC: intro to solutions and ConcentrationDo Now:

  2. Matter Pure Substances Mixtures Elements Compounds Homogeneous Mixtures Heterogeneous Mixtures Classification of Matter VIDEO

  3. Heterogeneous Mixtures • See visibly different regions • Granite • Dirt • Cereals • Oil & Vinegar • See a boundary • Ice cube in water

  4. Homogeneous Mixtures(SOLUTIONS) • Particlesvery small – on atomic scale • Can’t see particles • Can’t sort particles • Can’t get trapped by filter • Can’t scatter light • Particles evenly distributed • Particles do not separate

  5. Which is a solution & how do you know? CuSO4(aq)

  6. Solution Homogeneous mixture of 2 or more substances in a single physical state (phase)

  7. Parts of a Solution • Solute= dissolved substance • Solvent= dispersing medium

  8. Solute Solvent Example Gas Gas Air Liquid Gas Water Vapor in Air Solid Gas Mothballs Gas Liquid Seltzer Water Liquid Liquid Antifreeze in radiator Solid Liquid Salt water Gas Solid H2 in Pd metal Liquid Solid Fillings: Hg in Ag Solid Solid Alloys: Brass, etc. Solutions occur in all 3 phases!

  9. Gas dissolved in a solid

  10. Gas in a liquid:CO2 in and out of water How can you tell a gas is in a liquid??!? Bubbles mean it’s a mixture not a solution!

  11. Alloys Solid in solid Alloys

  12. We can determine how much solute and solvent make up a solution = CONCENTRATION • Concentration = A measurement that describes how much solute is in a given amount of solvent or solution. • Many, many different units to express concentration. • Molarity • PPM (parts per million) • % by mass • % by volume

  13. Molarity (M) Molarity (M) = moles of solute liters of solution

  14. So why do aqueous solutions need .1M or 3M in front?!?!?!

  15. VS

  16. Recall mole conversions moles FM g FM = formula mass Ex: Na3PO4 Na = 3 x 23 = 69 P = 1 x 31 = 31 O = 4 x 16 = 64 164g/mol 1 mol 1 mol grams FM g

  17. Rearranging … Molarity (M) = # moles of solute liters of solution Liters of solution = # of moles solute Molarity # moles of solute = Molarity x Litersof soln

  18. Twists • Sometimes give moles of solute; sometimes give grams of solute Gramsmust beconverted to moles • Sometimes give mL of solution instead of Liters Millilitersmust be converted to liters • Sometimes ask for: • grams/moles/volume of solute rather than molarity • NOTE: 1 g = 1 ml of water

  19. ---------------101 g/mol Practice before you start p.16-171. What is the formula mass ofa. KNO32. Convert to molesa. 58g NaCl3. Convert to L a. 500mlb. 10ml 4. Convert to gramsa. 1000ml b. 1L c. 50ml ---1 mol ---1000g ---1000ml = 1000g ---50g --0.5L ---0.01L

  20. Percent • By volume volume (solute) x 100% volume (solution) • By mass mass (solute) x 100% mass (solution)

  21. Mass solution = Mass solute + Mass solvent

  22. grams solution PPM (parts per million) • PPM = grams solute X 1,000,000 • used when solute is present in very small amounts (The Regents don’t follow this rule) • like % except you multiply by 1,000,000 instead of 100

  23. LET’S PRACTICE:About 0.0043 g of O2 can be dissolved in 100 mL of water at 20oC. Express in ppm. [Memorize: 1 mL water has mass of 1 g] • What is the solvent? • Water • How much solvent is there? • 100 mL = 100 g • How much solute is there? • 0.0043g • How much is the total solution? • 100 g + .0043 g = 100.0043g

  24. LET’S PRACTICE:About 0.0043 g of O2 can be dissolved in 100 mL of water at 20oC. Express in ppm. THE EQUATION ppm = 0.0043g X 1,000,000 100.0043g ppm = 43 ppm [Memorize: 1 mL water has mass of 1 g]

  25. NOW YOU TRY:CO2 gas has solubility of 0.0972 g/100 g water at 40oC; Express in parts per million ppm = 0.0972 g solute X 1,000,000 100.0972 g solution = 971 ppm

  26. HERE’S ANOTHER:What is the concentration in ppm of a solution with 30.0 g NaNO3 in 70.0 g water? ppm = 30.0 g NaNO3 X 1,000,000 100.0 g solution = 300,000 = 3.0 X 105 ppm

  27. LAST ONE:How many grams of KOH are needed to be dissolved in water to make 2000.0 grams of a 10.0 ppm solution? 10 ppm = X grams KOH X 1,000,000 2000.0 g solution X = 0.02 grams KOH

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