Chapter 12-2 January 25, 2017

Reminder You have a quiz tomorrow. It is on the information covered in class on Monday and Tuesday (12.1 and 12.2 up to Henry’s Law on the fill in the blank notes). The quiz is a combination of multiple choice and written questions.

Review Question #1 What are three ways to increase the rate at which a solute dissolves in a solvent?

Review Question #2 How can a supersaturated solution be created?

Review Question #3 A non-polar solvent will be able to dissolve ___________ solutes. It will not be able to dissolve ___________ solutes.

Review Question #4 Define the term immiscible

Review Question #5 Explain Henry’s Law

Surface Area Surface area is an important concept in all fields of science. In chemistry, increasing the surface area of a solute, it can be dissolved quicker as more of it is exposed at one time. Take for example the following two situations, both made out of 10 blocks. Do either samples have blocks that are not exposed?

Surface Area Your brain has the surface area of approximately two pages of newspaper when it’s all unfolded. Your small intestine has the surface area of approximately one full tennis court!

Temperature and Solubility Solids Dissolving in Liquids Gases Dissolving in Liquids Solids dissolve in liquids better when the temperature of the liquid is raised Gases dissolve better in liquids when the temperature of the liquid is colder. Why do you think this is?

Solubility Curves How many grams of KClO3 can dissolve in 100 grams of water at 55ºC?

Solubility Curves How many grams of NH4Cl can be dissolved in 200 grams of water at 40ºC?

Solubility Curves A saturated solution of NaNO3 is prepared at 70ºC in 100 grams of water. If the temperature is lowered to 40ºC, how many grams of NaNO3 will precipitate?

Solubility Curves If 35 grams of NH4Cl are dissolved in 100 grams of water at 30ºC, is the solution unsaturated, saturated, or supersaturated?

Effervescence Effervescence is the rapid escaping of gas from a liquid in which it was dissolved in. Where have you witnessed this before?

Review Question What’s the difference between intermolecular forces and intramolecular forces?

Creating solutions involves energy changes! During solution formation, changes occur in the forces between solvent and solute particles. Before dissolving begins, solvent and solute molecules are held to one another by intermolecular forces (solvent- solvent or solute-solute). Energy is required to overcome the intermolecular forces. A solute particle that is surrounded by solvent molecules is said to be solvated. The net amount of energy absorbed as heat by the solution when a specific amount of solute dissolves in a solvent is the enthalpy of solution.

Energy Changes Dissolving (dissolution) of a gas is an exothermic process. Dissolving (dissolution) of a solid can be either an exothermic or an endothermic

Hints or useful information 3. Ethanol is C2H5OH 4. You can skip this question 6. Water is polar. Toluene is non-polar. 7. You can skip number 7