Chapter 15 Solutions Solutions homogeneous mixtures containing two

  • Slides: 19
Download presentation
Chapter 15 = Solutions Ø Solutions = homogeneous mixtures containing two or more substances

Chapter 15 = Solutions Ø Solutions = homogeneous mixtures containing two or more substances l Solute = substance that gets dissolved; smallest part of solution l Solvent = substance that does the dissolving; largest part of solution

Ø Solutions are not always made of 2 liquids l Carbon + Iron l

Ø Solutions are not always made of 2 liquids l Carbon + Iron l Nitrogen + Oxygen

Ø Soluble = substance that can be dissolved in solvent l Sugar and water

Ø Soluble = substance that can be dissolved in solvent l Sugar and water Ø Insoluble = substance that can not be dissolved in solvent l Oil and water

Ø Miscible = two liquids are soluble in each other l alcohol and water

Ø Miscible = two liquids are soluble in each other l alcohol and water Ø Immiscible = two liquids are not soluble in each other l Oil and water

Ø Solvation- the process of solvent particles breaking apart solute crystals into particles the

Ø Solvation- the process of solvent particles breaking apart solute crystals into particles the size of ions l http: //www. glencoe. com/sites/common_assets /science/cmc/cim/animations/ch 14_1. swf

Ø Tyndall Effect l Solutions allow light to pass through without being scattered •

Ø Tyndall Effect l Solutions allow light to pass through without being scattered • Think about air l Non-solutions cause the light to be scattered • Think about fog We’ll cover this more in depth in section 15. 4

Ø Electrolyte- solutions that can conduct electricity due to ions in the solution

Ø Electrolyte- solutions that can conduct electricity due to ions in the solution

Ø Covalently bonded molecules do not break apart to form ions in solutions but

Ø Covalently bonded molecules do not break apart to form ions in solutions but they still do dissolve l http: //www. glencoe. com/sites/common_assets /science/cmc/cim/animations/ch 14_1. swf

Factors that Affect the Rate of Solvation Ø To increase solvation we need to

Factors that Affect the Rate of Solvation Ø To increase solvation we need to increase the number of times the solute and solvent touch 1. Shake (agitate) the mixture 2. Break to increase surface area 3. Bake—increase temperature

Ø Solubility-maximum amount of solute that will dissolve in a given amount of solvent

Ø Solubility-maximum amount of solute that will dissolve in a given amount of solvent at a specified temperature and pressure l Eventually, solute particles will begin to collide with each other and form crystals.

Ø Unsaturated l Contains less than maximum amount of dissolved solute Ø Saturated l

Ø Unsaturated l Contains less than maximum amount of dissolved solute Ø Saturated l Contains maximum amount of dissolved solute Ø Supersaturated l Contains more than maximum amount of dissolved solute

If you add extra solute to… Ø Unsaturated l Solute will dissolve Ø Supersaturated

If you add extra solute to… Ø Unsaturated l Solute will dissolve Ø Supersaturated l Solute will crystallize

Solubility Curves Ø Each substance has its own unique solubility which can be displayed

Solubility Curves Ø Each substance has its own unique solubility which can be displayed on a graph

Ø Supersaturated solution- solution holding more solute than a saturated solution at the same

Ø Supersaturated solution- solution holding more solute than a saturated solution at the same temperature and pressure l Mentos and Diet Coke • CO 2 is greater than normal levels • When Mentos are placed into the CO 2 jumps out of solution

Ø Temperature and Solubility l l SOLID- As temperature increases solubility of a solid

Ø Temperature and Solubility l l SOLID- As temperature increases solubility of a solid solute will increase (few exceptions) GAS- as temperature increases solubility of a gas will decrease

Ø Pressure and solubility l Henry’s Law – solubility of any gas increases as

Ø Pressure and solubility l Henry’s Law – solubility of any gas increases as the external pressure is increased • This is why cokes go flat. When you open the can the external pressure has been reduced and this decreases the solubility of the carbonation (CO 2)

Ø If 0. 55 g of a gas dissolves in 1. 0 L of

Ø If 0. 55 g of a gas dissolves in 1. 0 L of water at 2 atm of pressure, how much will dissolve at 4. 5 atm of pressure? 2 x = 2. 475 X= 1. 2375 g/L

Ø A gas has solubility of 0. 66 g/L at 10 atm of pressure.

Ø A gas has solubility of 0. 66 g/L at 10 atm of pressure. What is the pressure on a 1 L sample that contains 1. 5 g of gas? 0. 66 x = 150 X= 22. 73 atm

3. A gas has a solubility of 1. 46 g/L at 8 atm of

3. A gas has a solubility of 1. 46 g/L at 8 atm of pressure. What is the pressure of a 1. 0 L sample that contains 2. 7 g/L? answer = 14. 8 atm 4. If 0. 68 g of a gas at 5 atm of pressure dissolves in 1. 0 L of water at 25°C, how much will dissolve in 1. 0 L of water at 8 atm of pressure and the same temperature? answer = 1. 09 g/L