# Concentration. Differentiate among, and give examples of, the use of various representations of concentration. Include: g/L, % w/w, % w/v, % v/v, ppm,

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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 DilutionDilute MolarityM

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

1. Water/air quality: Parts per (ppm / ppb) Number of particles of solute for every million / billion particles solvent. 2. Industrial and household solutions: 3. Medical: g/L Describes quantities of solutes, like cholesterol or sugar in the blood/urine % 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

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

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

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

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

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

What is the molar concentration of a solution of copper (II) sulfate if 50.0 g is dissolved in 600 mL of solution? CuSO 4 = 159.6 g/mol 50.0 g 159.6 1 g mol 0.6 L = 0.5 M 0.313 mol n V M= = 0.6 L 50.0 g 159.6 g 1 mol

Preparing a Solution

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

Describe the steps needed to make 500.0 mL of a 0.50 M solution of sodium hydroxide. 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. n V M= = (0.500)(0.50) = 0.25 mol 1 40.0 mol g = 10.0 g

Concentration of Ions + -

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

mol NO 3 - mol Cu(NO 3 ) 2 Cu(NO 3 ) 2 (s) Cu 2+ (aq) + 2 NO 3 ¯ (aq) 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? 0.25 mol NO 3 - 1 2 187.5 1 g n V M= = (2.50)(0.100) = 0.25 mol NO 3 - = 23.4 g Cu(NO 3 ) 2 mol NO 3 - mol Cu(NO 3 ) 2 2.5 L NO 3 - 1 2 187.5 1 g 1 L 0.1 mol

CAN YOU / HAVE YOU? 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 DilutionDilute MolarityM

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