# 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.

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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

Ppm, % Composition, Molarity, and pH Get out your calculator!

1. 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?

2. 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

3. 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

4. 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

5. 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 -

ppm = amount solute 10 6 amount solution 6. 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

7. 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

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:

8. You have 0.800 L of a 0.500 M HCl solution. How many moles of HCl does this solution contain?

9. You have 3.50 L of solution that contains 90.0 g of sodium chloride, NaCl. What is the molarity of that solution? 90.0 g NaCl (58.44 g NaCl) (1 mol NaCl) = 1.54 mol NaCl

10. What volume of a 0.500 M solution of HBr is needed for a reaction that requires 32.5 g of HBr? 32.5 g HBr 80.91 g HBr (1 mol HBr) = 0.402 mol HBr

2 problems, 5 minutes! The answers should add up to 82.6 11. Calculate the volume of water (in ml) needed to make a 4.00 M solution using 50.6 grams barium fluoride? ANSWER: 72.1 ml (formula = BaF 2 ) 12. How many grams of potassium iodide must be added to 0.450 L water to make a 0.140M solution of this salt? ANSWER: 10.5 g (formula = KI)

13. What is the pOH of a 0.0075M nitric acid (HNO 3 )solution? pH = -log(0.0075) = 2.1 pOH = 14 – pH = 11.9 Formulas: pH = -log[H + ] pOH = -log[OH - ] [H + ] = 10 -pH [OH - ] = 10 -pOH pH + pOH = 14 14. What is the pH of a 0.0010 M solution of sodium hydroxide (NaOH)? pOH = -log(0.0010) = 3.0 pH = 11 1 HNO 3  1H + + 1NO 3 - Nitric acid is an acid and produces H+ in solution…..remember? [H + ] = M acid [OH - ] = M base NaOH is a base and produces OH- in solution…remember? 1NaOH  1Na + + 1OH -

15. What is the pH of a solution that contains 0.75 moles of hydrochloric acid (HCl) dissolved in 1.5 liters of water? pH = -log[H + ] [H + ] = [acid] [acid] = M = 0.75 moles/1.5L = 0.50M pH = -log(0.50) pH = 0.30 Formulas: pH = -log[H + ] pOH = -log[OH - ] [H + ] = 10 -pH [OH - ] = 10 -pOH pH + pOH = 14

16. What is the pH of a solution that contains 5.6 grams of sulfuric acid (H 2 SO 4 ) dissolved in 650 ml water? pH = -log[H + ] [H + ] = [acid] [acid] = M = moles/L moles: 5.6 g H 2 SO 4 (1 mole H 2 SO 4 ) 98.09 g H 2 SO 4 = 0.057090 moles Liters: 650 ml water  0.65 L M = 0.057090 moles/ 0.65 L = 0.0878307 M pH = -log(0.0878307) = 1.1 Formulas: pH = -log[H + ] pOH = -log[OH - ] [H + ] = 10 -pH [OH - ] = 10 -pOH pH + pOH = 14

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