LecturePLUS Timberlake1 Chapter 6.2 Dissolving and Solubility

LecturePLUS Timberlake2 Making process of dissolving FASTER! Many of same things that make chemical reactions go faster – But DISSOLVING IS A PHYSICAL CHANGE, NOT A CHEMICAL CHANGE.

LecturePLUS Timberlake3 Faster dissolving When a chunk of something dissolves, you are just pulling it apart into smaller bits (even down to individual molecules or ions)

LecturePLUS Timberlake4 Faster dissolving heat stirring shaking smaller chunks (larger surface area)

LecturePLUS Timberlake5 In a solution, the solute molecules are randomly distributed among the solvent molecules

LecturePLUS Timberlake6 Figure 15.1: Dissolving of solid sodium chloride.

LecturePLUS Timberlake7 The solvent is the substance that dissolves the solute to make a solution. The solute is the substance that dissolves in a solution.

LecturePLUS Timberlake8 Why is water such a great dissolver (solvent) for other substances?

LecturePLUS Timberlake9 Water is polar... It has a slightly negative “side” by the oxygen atom, and slightly positive “side” by the hydrogens.

LecturePLUS Timberlake10 Water can dissolve ionic compounds, and covalent compounds that are polar (have “slightly negative” and “slightly positive” parts).

LecturePLUS Timberlake11 The interaction of polar water molecules with ions

LecturePLUS Timberlake12 Representation of the polar hydrogen chloride molecule

LecturePLUS Timberlake13 Chlorine hogs the electron blanket, leaving hydrogen partially, but positively, exposed

LecturePLUS Timberlake14 Figure 15.3: The ethanol molecule contains a polar O— H bond.

LecturePLUS Timberlake15 Figure 15.3: The polar water molecule interacts strongly with the polar O—H bond in ethanol.

LecturePLUS Timberlake16 Soap The nonpolar side of a soap molecule is “attached” (attracted to) nonpolar grease and oil, the polar side hangs on to the water, and the dirt slips off your hands and is pulled down the drain, trapped, along with the water molecules, by that pesky soap molecule!

LecturePLUS Timberlake17 (a) non-polar gasoline and non-polar oil mix (b)polar vinegar and nonpolar oil do not mix (c) polar water and polar ethyl alcohol mix

LecturePLUS Timberlake18 Figure 15.6: An oil layer floating on water.

LecturePLUS Timberlake19 For a more detailed explanation of why polar and nonpolar materials can’t dissolve each other: article/0,1406,KNS_9116_ ,00.h tmlhttp:// article/0,1406,KNS_9116_ ,00.h tml

LecturePLUS Timberlake20 Saturated and Unsaturated A saturated solution contains the maximum amount of solute that can dissolve. Undissolved solute remains. An unsaturated solution does not contain all the solute that could dissolve

LecturePLUS Timberlake21 Supersaturated Solutions

LecturePLUS Timberlake22 To see more of this supersaturation experiment: ersat/supersat.htmhttp:// ersat/supersat.htm

LecturePLUS Timberlake23 To see more exciting supersaturation stuff, go to: Crystallization from Supersaturated Solutions of Sodium AcetateCrystallization from Supersaturated Solutions of Sodium Acetate Note, you may need to hit “refresh” to get demonstration started and restarted.

LecturePLUS Timberlake24 Solubility The maximum amount of solute that can dissolve in a specific amount of solvent usually 100 g. g of solute 100 g water

LecturePLUS Timberlake25 Molarity Concentration unit of a solution that expresses moles of solute dissolved per liter of solution. To make a 1 molar solution of a substance, put 1 mole of stuff into a container and add solvent (usually water) up to the “1 liter” mark.

LecturePLUS Timberlake26 Not this type of Mole

LecturePLUS Timberlake27 Or this type of Mole

LecturePLUS Timberlake28 Mole 6.02 x is a mole - 602,000,000,000,000,000,000 If you counted paper at the rate of one sheet per second it would take you 19,089,294,774,226,281 years to count a mole of paper. It is a big number because atoms are small.

LecturePLUS Timberlake29 A mole of sugar weighs about one half pound but contains how many molecules of sugar? 602,000,000,000,000,000, x molecules.

LecturePLUS Timberlake30 Temperature and Solubility of Solids TemperatureSolubility (g/100 g H 2 O) KCl(s)NaNO 3 (s) 0° °C °C °C Does the solubility of solids seem to increase or decrease with an increase in the temperature?

LecturePLUS Timberlake31 A. Why would a bottle of carbonated drink possibly burst (explode) when it is left out in the hot sun ? B. Why would fish die in water that gets too warm?

LecturePLUS Timberlake32 Solutions A. Gas in the bottle builds up as the gas becomes less soluble in water at high temperatures, which may cause the bottle to explode. B. Because O 2 gas is less soluble in warm water, the fish may not obtain the needed amount of O 2 for their survival.