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Concentration

Concentration. Differentiate among, and give examples of, the use of various representations of concentration . Include : g/L, % w/w, % w/v, % v/v , ppm, ppb Solve problems involving calculation for concentration, moles, mass, and volume. Additional KEY Terms Dilution Dilute

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Concentration

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  1. Concentration

  2. Differentiate among, and give examples of, the use of various representations of concentration. • Include:g/L, % w/w, % w/v, % v/v, ppm, ppb • Solve problems involving calculation for concentration, moles, mass, and volume. • Additional KEY Terms • Dilution Dilute • Molarity M

  3. Concentrated Solution with a lot of solute compared to solvent. Dilute Solution with a little solute compared to solvent.

  4. 1. Water/air quality: Parts per (ppm / ppb) • Number of particles of solute for every million / billion particles solvent. 2. Industrial and household solutions: • % w/v– grams of solute in 100 mL of solution. • % v/v – mL of solute in 100 mL of solution • % w/w –grams of solute in 100 g of solution • 3. Medical: g/L • Describesquantities of solutes, like cholesterol or sugar in the blood/urine

  5. Moles of solute n Litres of solution V Concentration units in chemistry: mol/L - moles of solute in one Litre of solution. = Molar concentration M = Known as molarity

  6. Calculate the concentration of a NaCl solution if 0.200 moles is dissolved in 250 mL of solution. 250 mL 1 L = 0.25 L 1000 mL n V 0.200 mol = 0.80 mol/L 0.25 L M = 0.80 M (pronounced "mol-er")

  7. 5.0 mol 1 L 4.00 L = 1.25 mol What volume of a 1.25 M solution contains 5.00 moles of solute? n V = M = V = 4.00 L 5.00 mol 1.25 M

  8. How many moles of solute needed to make 400 mL of a 0.225 M solution? n n = (0.4)(0.225) M = V = 0.09 mol 400 mL 1 L 0.225 mol 1 L 1000 mL = 0.09 mol

  9. What mass of sodium chloride is needed to make 0.250 L of a 0.100 M solution? NaCl = 58.5 g/mol n M = = (0.250)(0.100) V =0.0250 mol 0.1 mol 58.5 g 0.250 L 1 mol 1 L = 1.46 g 0.025 mol 58.5 g 1 mol

  10. What is the molar concentration of a solution of copper (II) sulfate if 50.0 g is dissolved in 600 mL of solution? n V 0.313 mol 0.5 M = 0.6 L CuSO4 = 159.6 g/mol 1 mol 50.0 g 0.313 mol = 159.6 g 1 mol 50.0 g 0.6 L 159.6 g M =

  11. Preparing a Solution

  12. To make a solution follow a few basic steps: 1. Determine the massof the solute needed. 2. Add the solid to a flask or beaker. 3. Pour in half the solvent and swirl to dissolve. 4. Add solvent to the right volume. 5. Mix the solution further. Adding solute will change the volume of the solvent.

  13. Describe the steps needed to make 500.0 mL of a 0.50 M solution of sodium hydroxide. n M = = (0.500)(0.50) V = 0.25 mol = 10.0 g i. Mass out 10.0 g of NaOH. ii. Add the solid to a 500 mL volumetric flask. iii. Fill the flask half-full with water and swirl until dissolved. iv. Fill the flask to the 500 mL mark, continue to mix. 40.0 g 1 mol

  14. + Concentration of Ions -

  15. What is the [Cl-] in 0.200 M solution of aluminum chloride? 3 AlCl3 (s) Al+3(aq) + Cl-1(aq) 0.200 mol AlCl3 3 mol Cl- 0.600 M Cl- = 1 L 1 mol AlCl3

  16. What mass of copper (II) nitrate is needed to make 2.50 L of a solution that has a nitrate ion concentration of 0.100 M? Cu(NO3)2 (s) Cu2+(aq) + 2 NO3¯(aq) n = (2.50)(0.100) M = V = 0.25 mol NO3- mol Cu(NO3)2 187.5 g 2.5 L NO3- 1 0.1 mol 1 mol Cu(NO3)2 187.5 g 0.25 mol NO3- 2 mol NO3- 1 L mol Cu(NO3)2 1 2 mol NO3- mol Cu(NO3)2 1 = 23.4 g Cu(NO3)2

  17. CAN YOU / HAVE YOU? • Differentiateamong, and give examples of, the use of various representations of concentration. • Include:g/L, % w/w, % w/v, % v/v, ppm, ppb • Solve problems involving calculation for concentration, moles, mass, and volume. • Additional KEY Terms • Dilution Dilute • Molarity M

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