Solutions

What is a Solution? A solution is a mixture that has the same composition, color, density, and even taste throughout. Solutions are homogenous mixtures.

What is in a Solution? Solutions are made of 2 parts: Solute: The substance that is dissolved (ex: sugar, salt, kool-aid) Solvent: The substance doing the dissolving (ex: water) Water is considered a universal solvent

Dissolving Process Remember the kinetic theory All matter is made up of tiny particles (atoms, molecules, etc) Molecules are always moving Molecules randomly collide When we dissolve sugar in water: Water molecules attach to OUTSIDE of sugar molecules and break the sugar apart Works from the outside  in

Dissolving Process The solvent (water) molecules work on the outside of the solute (salt) to break it down.

Ways to increase dissolving Increasing collisions between solute and solvent will increase dissolving between molecules. The following all increase the rate at which substances dissolve in a solvent. Stirring increases Increasing temperature (hot can hold more than cold) Increasing the surface area (making smaller pieces)

Concentration The quantity of solute dissolved in a given quantity of solvent Dilute = small amount of solute dissolved in solvent Concentrated = large amount of solute dissolved in solvent

So how much solute is there? 3 Different Type of Solution: Based on the amount of solute compared to the solvent Saturated Solution = Solution that has the maximum amount (mass) of the solute dissolved in the solvent  Unsaturated = solutions that has less than the maximum amount of solute dissolved and is able to dissolve more solute  Supersaturated = solution that has more than the maximum amount of solute in it Having too much solute means some will pile up on the bottom of the container

Solubility Values Each substance has a different solubility value. The value tells us how much of a substance will dissolve in a certain volume under a certain temperature Raising the temperature increases the solubility value The solute stops dissolving at equilibrium – Equilibrium = balance of solute molecules coming and going from solution Or we can check wikipedia SubstanceSolubility Value (g/100mL water 20 o C) Solubility Value (g/100mL water 30 o C) Table Salt (NaCl)35.9 g36.1 g Sugar (C 12 H 22 O 11 )203.9 g211.4 g Baking Soda (NaHCO 3 )9.6 g11.1 g

How Much Will Dissolve? - HONORS – How much table salt will dissolve in 250mL of water at 20degC? 35.9g SaltX X g salt 8975 = 100x 100mL water250mL=> = grams of Salt – How much water would you need to dissolve 150g of sugar at 20degC? 203.9g SugarX 150 g sugar = 203.9X 100mL waterX mL=> = mL of water AND WE CAN EVEN CHANGE THE TEMPERATURE: – How much water would you need to dissolve 150g of sugar at 30degC? g sugar X 150 g sugar = X 100mL waterX mL=> = mL of water