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Solutions Review

Solutions Review. Boon Chemistry January 08 and 09, 2013. Catalyst. Write at least five sentences answering any or all of the following questions: What was the best part of your winter break? What are you looking forward to in 2013? What are your academic goals for spring semester?.

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Solutions Review

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  1. Solutions Review Boon Chemistry January 08 and 09, 2013

  2. Catalyst • Write at least five sentences answering any or all of the following questions: • What was the best part of your winter break? • What are you looking forward to in 2013? • What are your academic goals for spring semester? • Objectives • I can calculate the concentration of a solution. • I can describe the dissolving process on the molecular level. • Agenda • Catalyst Share Out • Solutions Review Foldable • Whiteboard Practice: Concentration • Intermolecular Forces Article

  3. Catalyst Share Out Over winter break, I enjoyed spending time with my friends and family. In 2013, I look forward to attending the weddings of several of my friends and spending time with my family. One of my academic goals is to push all students to complete more challenging activities and shoot for an “A” or “4” on all assignments.

  4. This week is “re-teach week.” • Student performance on the benchmark exam was similar to student performance on the final exam. • Student scores were distributed approximately as follows: • 5% - Advanced (mostly 4’s) • 45% - Proficient (mostly 3’s) • 45% - Basic (mostly 2’s) • 5% - Below Basic (mostly 1’s) • The majority of students scored 2’s and 3’s. • The benchmark was part of the fall semester grade.

  5. This week is “re-teach week.” • In today’s class, we will review and dig deeper into the following standards related to Solutions: • Standard 6a: Students know the definitions of solute and solvent. • Standard 6d: Students know how to calculate the concentration of a solute in terms of grams per liter, molarity, parts per million, and percent composition. • Standard 2d: Students know the atoms and molecules in liquids move in a random pattern relative to one another because the intermolecular forces are too weak to hold the atoms or molecules in a solid form.

  6. Review Activities • Today: • Solutions Foldable • Concentration Whiteboard Practice • Article: Intermolecular Forces • Homework: complete the foldable and intermolecular forces questions if you did not finish in class. • Next Class: • Quiz: Standards 6a, 6d, 2d Benchmark Redo – you may use your foldable and article

  7. Solutions Foldable • Follow along to fold up your foldable. • Fold in half along the lines. • Then fold each corner in to make a smaller square. • You should have a square with four triangular flaps.

  8. Solutions Foldable • Label your foldable. • Top Left: Percent concentration is the number of grams of solute per 100 grams of solution. • Top Right: Grams per Liter is the number of grams of solute in one liter of solution. • Bottom Left: Molarity is the number of moles of solute in one liter of solution • Bottom Right: Parts per million is the number of grams of solute in 1,000,000 g solution.

  9. Finding the Percent Concentration % concentration = g solute___ x 100% g solution The denominator is the mass of solution. Add: g solute + g solvent Example 1: Household ammonia is a cleaning product that is a solution of ammonia (NH3) and water (H2O). What is the percent concentration of ammonia in a solution containing 20 g NH3 and 180 g H2O?

  10. g/L = # grams solute 1 liter of solution Example 1: A 222 mL can of Coca-Cola contains 25 g of sugar. What is the concentration of sugar expressed in g/L?

  11. M = mol L Calculating Molarity Example 1: A sample of stomach acid (hydrochloric acid or HCl) contains 0.02 mol of HCl in 2.0 L water. What is the molarity of the solution?

  12. Calculate parts per million Note: ppm is used in pollution measurements that involve very low concentrations. ppm= g solute______ 1,000,000 g solution Step 1: Convert all measurements into grams. Step 2: Find the grams of solute in 1 g solution by dividing (g solute/g solution). Step 3: Multiply by 1,000,000 to find ppm. Example 1: A chemist analyzes a 500 g water sample and finds that it contains 1.0 mg of mercury. Convert this measurement to parts per million.

  13. White Board Practice #1 • A sample of 400 g water contains 40 mg of lead (Pb). What is the concentration in parts per million? • A solution of lead sulfate contains 0.5 g of lead sulfate in 100 g of water. What is the concentration in parts per million? • A 500 mL can of Mountain Dew contains 40 g sugar. What is the concentration of sugar expressed in grams per liter? • Calculate the concentration in #3 in molarity. (molar mass of sucrose = 342 g/mol) 100 ppm 5000 ppm 80 g/L 0.23 M

  14. White Board Practice #2 • What is the molarity of 0.6 mol of NaCl dissolved in 200 mL of water? • Brass is an alloy (mixture) of copper and zinc. A 500 g brass doorknob contains 300 grams copper and 200 grams zinc. What is the percent concentration of copper? • What is the percent concentration of zinc in the doorknob from #2? • A 500 mL can of soup contains 250 mg NaCl. What is the concentration of NaCl in grams per liter? 3 M 60% copper 40% zinc 0.5 g/L

  15. Intermolecular Forces: Introduction Think Pair Share: The pictures show water dissolving salt. Take turns explaining what you see in the picture with the person next to you. Why and how do you think this process works?

  16. Intermolecular Forces: Introduction • Intermolecular forces are the forces of attraction or repulsion between different molecules. They are weaker than chemical bonds but they influence many physical and chemical properties like melting point, boiling point, solubility, and 3D molecular structure.

  17. Intermolecular Forces The intermolecular forces are only effective when molecules are near each other. The diagram below shows a solid, liquid, and gas. (a) Which has the strongest intermolecular forces? (b) Which has the weakest intermolecular forces? 1 2 3

  18. Independent Work Time • Expectations: • You must work at your seat. You may speak quietly to the students next to you. • Raise your hand if you need help. • You may get up to check your answers. • You may work on the following: • Solutions Foldable: concentration problems and solutions vocabulary review puzzles. • Intermolecular Forces Article: Practice Questions • Answers are posted at the front of the class. • Correct your work. You may use these handouts on the benchmark review quiz.

  19. Homework • Finish all worksheets: you get to use them on your quiz on Thursday/Friday. • Optional: bring index cards and white board marker • Due next Monday: your daily work organizer

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