Solution Concentration

Context Both molecular and ionic compounds can dissolve it water We can calculate the moles of something if we know the mass… How much are dissolved in moles per litre?

Dilute Solutions Small quantity of solute per unit volume of solution. Concentrated Solutions Large quantity of solute per unit volume of solution.

Concentration The concentration of a solution is the quantity of solute in a solution. C = quantity of solute quantity of solution

% Concentration This format is common on household and drugstore products ▫Ex: Vinegar is reported at 5% acetic acid ▫Ex: Hydrogen peroxide is 3% ▫What does this mean?

Three types v/v % (when solute is a liquid) V solute x 100%ml/100ml V solvent m/v % (when solute is a solid) m solute x 100%g/100ml V solvent m/m % (when both solute & solvent are solids) m solute x 100%g/100g m solvent

Everyday Examples Vinegar is 5% v/v acetic acid ▫5 mL of CH 3 COOH in 100 mL vinegar Hydrogen peroxide is 3% m/v ▫3 g of H 2 O 2 per 100 mL of solution Yogurt is 2% m/m ▫2 g of milk fat per 100 g yogurt

Example Milk fat is present in milk. Whole milk usually contains about 3.25% m/V milk fat. If you drink a 250mL glass of milk, what mass of fat have you consumed? % m/v =m solute x 100% v solvent 3.25 =m solute x 100% 250mL m solute = 8.13 g of milk fat

ppm Parts per million Can also have ppb, ppt Useful for reporting very small quantities Often used in ecology and toxicology Look for it on your bottled water 1 ppm = 1mg/1L 1 ppm = 1mg/1kg ▫ppm = 1 drop in a bath tub ▫ppb = 1 drop in a swimming pool ▫ppt = 1 drop in a 1000 swimming pools

E.g what is the molarity of a 250 mL solution that contains 2.00 g of NaOH? Concentrations in Chemistry Molar concentration (molarity) ▫Moles of solute dissolved in one liter of solution ▫Units: mol/L (or lazy chemists sometimes use M) ▫[ ] is molar concentration n = 2.00 g g/mol = mol C = mol L = mol/L M = g/mol m = 2.00 g V = L n = ? C = ?

Practice P. 305 # 1-3 P. 308 # 5,7 P. 310 # 10, 11 P. 316 # 19a,c,e, 20a,c,e, 21-23