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AS Chemistry

AS Chemistry. Chapter 15 Mixtures and Solutions. Soluble song. Is it uniform throughout?. If the answer is no, the matter is a heterogeneous mixture. Considered the “least mixed.” Does not appear to be the same throughout.

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AS Chemistry

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  1. AS Chemistry Chapter 15 Mixtures and Solutions

  2. Soluble song

  3. Is it uniform throughout? • If the answer is no, the matter is a heterogeneous mixture. • Considered the “least mixed.” • Does not appear to be the same throughout. • Particles are large enough to be seen and to be separated from the mixture.

  4. Examples of heterogeneous mixtures • Sand and pebbles • Oil and water • Powdered iron and powdered sulfur

  5. Granite is a heterogeneous mixture.

  6. Sec. 1 + 4 Types of mixtures • Heterogeneous • You can tell there are 2 or more substances • Suspensions s-l a) will settle out b) can be filtered c) will scatter light (tyndall effect) d) larger than 1000 nanometers (nm) • Dirty water • Tyndall effect

  7. Colloids • Between 1 and 1000 nm dispersed particles (hard to see them) • Examples jello, milk, egg white, smoke, clouds • Tyndall effect, don’t tend to settle out, hard to filter

  8. Is it uniform throughout? • If the answer is yes, the matter is homogeneous (looks the same throughout).

  9. Solutions • A solution is a type of homogeneous mixture formed when one substance dissolves in another. • It is the best mixed of all mixtures. • A solution always has a substance that is dissolved and a substance that does the dissolving. • The substance that is dissolved is the solute and the substance that does the dissolving is the solvent. • If there is more it’s the solvent if the substances are in the same phase

  10. The universal solvent: Water

  11. Water as a solvent • Many liquid solutions contain water as the solvent. • Ocean water is basically a water solution that contains many salts. • Body fluids are also water solutions.

  12. Types of solutions Solute Solvent Example Metals dissolved in metals are called alloys.

  13. Solution animation

  14. Types of solutions

  15. d • This type of mixture is characterized by a settling of particles: • a)hydrate b) solution c) colloid d) suspension

  16. The following mixture(s) can be filtered to remove solid material. • a) colloids only c) colloids and solutions • b) suspensions only d) suspensions and colloids • Answer is b

  17. Which of the following type(s) of mixtures exhibit(s) the Tyndall effect? • a) suspensions only c) colloids and suspensions • b) colloids only d) colloids, suspensions and solutions • Answer is c

  18. Section 2 concentration • Many ways to express this • % by mass or volume • like D5W which is a .5% sugar solution or normal saline which is 0.9% sodium chloride (table salt) in IV solutions • A volume example is 70% isopropyl (rubbing) alcohol

  19. The equation is • Mass (or volume) of solute ÷ mass (or volume) of solution x 100 • How would you make up a normal saline solution? • Do problems 8-10 page 463 • Do problems 11-12 page 464 • Check your answers on page 942

  20. Molarity (M)is a more precise way to do concentration as it goes by particles not mass • Moles of solute ÷ liters (dm3) of solution • IB is mol . dm-3

  21. What is the molarity of a normal saline solution 0.9 g in 100 mL of water solution? • 0.9 / 58.5 g/mol = 0.0154 100ml /1000= .1 • 0.154 M • What is the molarity of a D5W solution 5 g of dextrose (mm 180) in 100 mL of water ? • 0.278 M

  22. Do 14-16 page 465 • Answers on page 942

  23. Preparing Molar solutions • How do you make up 500 mL of a 0.25 molar NaCl solution? • 0.25 mol/L x 0.5 L = 0.125 mol • 0.125 mol x mm(58.5 g/mol) = 7.31 g of NaCl • Put 7.31 g in a volumetric flask and dilute to 500 mL

  24. Do problems 17-19 page 467 • Check you answers on 942

  25. How many grams of NaCl are dissolved in 500.0 mL of a 0.05M solution of NaCl?A)0.05 g B)0.29 g C)1.46 g D)2.92 g • c

  26. Diluting stock solutions • Prepare 500 mL of a 0.1 M HCl solution using a 12 M stock solution • M1V1 = M2V2 • 12 M x V1 = 0.1 M x 0.500 L • V1 = (0.1 x 0.500 L) ÷ 12 • Use 0.00417 L or 4.17 mL and dilute to 500 mL

  27. Do 21 and 22 page 468 • Answers on page 942

  28. Molality (m) • To avoid the change in volume due to temperature a unit using mass is used • m = mol of solute / kg of solvent • Water 1 kg = 1L or 1g = 1mL • 4.50 grams of NaCl is added to (not diluted to)495.5 g of water. What is its molality (this is a normal saline solution) • 4.5/58.5 mol ÷.4955 kg = m

  29. Do 24 and 25 page 469 • Answers on page 942

  30. Mole fraction • One more way to express concentration • X mol of solute/ mol of solution • Change g to moles and divide by the total • What is the mole fraction of a 5% NaCl solution?

  31. Do questions 26 and 27 page 470 • Answers on page 942,3

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