Mixtures

Two types Heterogeneous mixtures: - at least 2 substances that can be seen with naked eye Ex. Granite rock – can see different coloured minerals

Homogeneous mixtures - mixture with at least 2 substances that cannot be seen with naked eye. ex. Colloids and solutions

Colloids: homogeneous mixture in which two substances can be distinguished under a magnifying instrument. Ex. Blood, Milk naked eye Under microscope

Solutions - homogeneous mixture - impossible to distinguish constituent parts (not even with microscope) - one visible phase, Translucent? Transparent? - phase of solution determined by the solvent (see table 1.15, page 13)

Dissolution - when a solution is made the solute is dissolved by the solvent. - Solute: substance that dissolves in another substance Solvent: substance that can dissolve a solute Ex. Salt water(solution): salt (solute), water (solvent) Human Body: Lymph (solution): waste (solute), water (solvent) Tears (solution): salt (solute), water (solvent) Urine (solution): salts, wastes (solutes), water (solvent)

Making a solution Dissolution Particle Model

Particle Model-Dissolution - solute appears to disappear - bonds between the solute molecules break - solute dissolves between the particles of the solvent - solute becomes microscopic.

Concentration Quantity of dissolved solute in a given quantity of solution. Units: g/ L % m/V % V/V % m/m Formula: C = m_ V C= concentration(g/L) m= mass solute (g) V= volume solution (L)

Example 1: Kenny makes a 50 L solution by dissolving a 100 g of salt in water. What is the concentration of the solution? C = m/V means “mass ÷ volume” C= 100 g/ 50 L C= 2 g/L

Example 2: Kelsey makes a 2 g/L with a volume of 500 mL. How much solute did she use? Covert mL to L :500 mL ÷ 1000 = 0.5 L C= m/V 2 = m 0.5 m= 2 (0.5) = 1 g/L

Example 3: Chris buys a 650 ml bottle of contact lens saline (salt water) solution with a concentration of 3%. How much salt is in the solution? Convert % to g over 100 mL: 3% = 3 g per 100 mL 3_ = m_ 100 650 now cross-multiply! 100 m = 3 (650) 100 m = 1950 m = 1950 ÷100 = 19.5 g

Changing the concentration of a solution Dilution – adding solvent to decrease concentration Concentrate – add solute Use this formula (C1V1=C2V2) to find the concentration of a diluted solution.

Example 2.5g of salt were dissolved in 1L of water. The solution was then diluted by adding 3L of water. What is the concentration of the new solution?

Solubility Refers to the maximum amount of solute that can be dissolved in a given amount of solvent. When a solution is supersaturated, the surplus solute appears as a precipitate. Solubility is affected by the nature of the substance and temperature.

  What is the solubility of NaCl at 900C? At what temperature is the solubility of KNO3 about 87 g/100 g? What would a solution be called if 125 g of NaNO3 were dissolved at 800C If the solution in number 3 was cooled to 500C, how much precipitate would form?