Rate of Dissolution

Factors in dissolving

Warm-up: What are the 7 types of colloids?

Short Lab

• 1. Weigh out a 6 gram sample of copper sulfate. Place in crucible and heat leave the lid slightly open to allow gas to escape. let heat for 4 min

• 2. weigh the sample after cooling for 5 min

• 3. split into 6 equal samples.

• 4. measure about 25 ml of water in each of your 2 beakers. place 1 equal weight sample in each after crushing with a mortar and perstle. leave one sample to sit and stir the other. make sure to make observations

• 5. rinse beakers. Measure out another 25ml in each beaker. Crush one sample leave the other in crystal form. let each sample sit in the water as the dissolve. make observations

• 6. rinse beakers. measure out 25 ml of water in each beaker. Heat one on the hot plate. crush each sample and place in beaker watching them dissolve. make observations

• 7. Rinse beakers.

Factor: Surface area

• Which dissolves faster sugar or a sugar cube?

• Crushing a material will increase the surface area of the material that is interacting with the solvent. This makes dissoving it easier

• Higher temperatures increase the movement of particles, increasing collisions between particles

• Stirring or shaking a liquid disperse particles and increase collisions

Solubility

• A higher solubility has more ability to dissolve.

• Can be in solution equilibrium- dissolving and crystallizing happen at the same rate

• saturated solution- solution containing the maximum amount of dissolved solute

• unstaurated solution- solution containing less than the maximum amount of solute

• Supersaturated solution-solution contains more dissolved solute than a saturated solution under the same conditions

Solubility

• Every substance has a differerent solubility

• Like dissolves like- does not always apply.- Polar dissolves polar, nonpolar dissolves nonpolar

• water does not dissolve oil, but it will dissolve alcohol

• If a compound is ionic- it is siad to be hydrated by water

• hydration- solution process with water as the solvent

• hydrates- crystals that retain water- can be dehydrated

Liquids and gases

• imiscible-If liquids are not soluble in each other

• miscible-If liquids are soluble in each other

• Pressure affects solubility- it increases the solubility of gas but eventually equilibrium will be reached- Henry's Law: solubility of a gas in a liquid is driectly proportional to the partial pressure of the gas on the liquid

• Effervesecence- rapid escape of a gas from the liquid it is dissolved in

• Substances have varying levels of solubility at temperatures