1. Warmup (5 minutes) (please draw in lone pairs yourself) 1. Rank these molecules from most(1) to least(5) polar HO-HHO-H H H H-C-O-C-H H H H H H H H H-C-C-C-C-C-OH H H H H H H H O H H-C-C-C-H H H H n-amyl alcohol H H H H H H H-C-C-C-C-C-C-H H H H H H H 2. Which compound to the right would be the best solvent for NaCl? Explain. methanol H-O-Cl hexane isopropyl alcohol dihydrogen monoxide 1 2 4 3 5 H H-C-O-H H

2. Concentration Part 1 Percent Composition and Parts Per Million Get out your calculator!

3. 1.Which salt solution has the greatest concentration? [ ] is a measure of the amount of solute in a given amount of solution Beaker A 3 molecules 100 mL solution Beaker B 5 molecules 100 mL solution Beaker C 7 molecules 200 mL solution

4. 2. What is the percent composition of girls and boys in the AP chem class shown? # Girl students? # Boy students? Total # students?

5. 3. A bottle contains 500. mL of water. If this solution has 15.5 mL of pure hydrogen peroxide, what is the concentration of hydrogen peroxide in this solution?

6. 4. I dilute 10.0 mL of HBr to make a 42.5% HBr solution. What will the total volume of the solution be? percent composition = amount solute 100 amount solution 42.5 = 10.0 ml 100 x 42.5 x = 10.0 ml (100) x = 23.5 ml Hmmmm…..how much of the solution is just solvent (water)? ______ ___________ 42.5 42.5

7. 5. If a concentrated solution of hydrogen peroxide has a percent composition of 65%, how many mL of pure hydrogen peroxide would be contained in a 0.750 L solution? percent composition = amount solute 100 amount solution 65= x_ 100 0.750 L 65 (0.750 L) = x 100 0.49 L = x 0.49 L (1000 ml) = 1 L 490 ml

8. 6. What mass (in grams) of NaCl is necessary to make a 5.0% NaCl solution using 82 ml (82 GRAMS) of water? JUST WATER! percent composition = amount solute 100 amount solution 5.0= x _ 100 x + 82 5.0 (x + 82) = x (100) 5.0x + 410 = 100x 410 = 95xx = 4.3 grams NaCl

9. 7. For cavity prevention, the recommended concentration of fluoride ions in our drinking water is 0.7 to 1.2 parts per million (ppm). Too much fluoride can result in discolored teeth. If the concentration of F - in Orange County is 0.85 ppm, what mass of fluoride would be contained in a 7.2 gram tap water sample from and OCHSA bathroom? ppm = amount solute 10 6 amount solution 0.85 = x grams F - 10 6 7.2 gram 0.85 (7.2 gram ) = x grams F - 10 6 6.1 x 10 -6 g F -

10. ppm = amount solute 10 6 amount solution 8. What is the concentration of mercury (in ppm) if 3 grams mercury is found in a 15 kg sample of ocean water? 15 kg (1000g) = 15000 g 1kg x ppm = 3 g 10 6 15000 g x ppm = 3 g (10 6 ) 15000 g x = 200 ppm

11. 9. What mass of mercury (in grams) would be contained in a 40.0 kg sample of ocean water at this same concentration? 40.0 kg (1000g) = 4 x 10 4 g 1kg ppm = amount solute 10 6 amount solution 200 ppm = x g Hg 10 6 4 x 10 4 g 200 ppm(4 x 10 4 g) = x = 8 g Hg 10 6

12. Análisis químico mg/l (ppm) Calcio11.9 Magnesio10.3 Hierro menos de0.1 Flúor menos de0.1 Sodio7.0 pH6.63 Potasio4.7 Sulfatos4.0 Dureza del calcio29.7 Dureza del magnesio 35.7 Alcalinidad total67.8 S.T.D184 El Agua Cristal es mejor porque ha sido filtrada por la naturaleza durante décadas, adquiriendo de manera natural los minerales necesarios para un perfecto equilibrio del organismo. La NSF certifica que Agua Cristal cumple con las más estrictas normas de calidad requeridas por la FDA de los Estados Unidos. Un envase de 600 ml contiene:

13. Sweet! Concentration Concepts!  Work in lab groups  Pour ‘solution’ back into ‘original solution’ when you’re done  We haven’t done all the concentration types YET, but you can go back and do those problems later if you can’t figure them out today (formulas are all given)  Don’t eat anything