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Flashcards in Ch 12 Section 2 Deck (88):
1

molecules or ions of the solute are

attracted by the solvent

2

because the dissolution process occurs at the surface of the solute, it can be speeded up if the surface area of the solute is

increased

3

in general, the more finely divided a substance is, the greater the surface area per unit mass and the more

quickly it dissolves

4

very close to the surface of a solute, the concentration of dissolved solute is

high

5

stirring or shaking helps to disperse the solute particles and bring fresh solvent into

contract with the solute surface

6

the effect of stirring results in increased contact between the

solvent and the solute surface

7

as the temperature of the solvent increases, solvent molecules move faster, and their

average kinetic energy increases

8

at higher temperatures, collisions between the solvent molecules and the solute are more frequent and are of higher energy than at

lower temperatures

9

this helps to separate solute molecules from one another and to disperse them among the

solvent molecules

10

for every combination of solvent with a solid solute at a given temperature, there is a limit to the amount of solute that can be

dissolved

11

the point at which this limit is reached for any solute solvent combination is difficult to predict precisely and dpends on the nature of the

solute, nature of the solvent, as well as the temperature

12

as more solid dissolves and the concentration of dissolved molecules increases, collisions become more

frequent

13

eventually, molecules are returning to crystal at the same rate at which they are going into solution, and a dynamic equilibriuim is established between

dissolution and crysstallization

14

solution equilibrium is the physical state in which the opposing processes of dissolution and crystallization of a solute occur at

equal rates

15

a solution that contains the maximum amount of dissolved solute is described as a

saturated solution

16

a solution that contains less solute than a saturated solution under the existing conditions is an

unsaturated solution

17

when a saturated solution of a solute whose solubility increases with temperature is cooled, the excess solute usually comes out of solution, leaving the solution satureated at the

lower tempearture

18

sometimes, if the solution is left to cool undistrubted, the excess solute does not separate and a

supersaturated solution is produced

19

a supersaturated solution is a solution that contains more dissolved solute than a saturated solution contains under the

same conditions

20

a supersaturated solution may remain unchanged for a long time it if is not disturbed, but once crystals begin to form, the process continues until equilibrium is

reestablished at the lower temperature

21

the solubility of a substance is the amount of that substance required to form a saturated solution with a specific amount of ... at a specified ...

solvent; temperature

22

the temperature must be specified because solubility varies with

temperature

23

for gases, pressure must also be

specified

24

the rate at which a solid dissolves is unrelated to its solubility at that

temperature

25

the maximum amount of a given solute that dissolves and reaches equilibrium is always the same under the

same conditions

26

"like dissolves like" is a useful rule for predicting whether one substance will

dissolve in another

27

what makes substances similar depends on the type of bonding, the polarity or nonpolarity of molecules, and the intermolecular forces between the

solute and solvent

28

the polarity of water molecules plays an important role in the formation of solutions of

ionic compounds in water

29

the slightly charged parts of water molecules attract the ions in the ionic compound and surround them to keep them separated from the other

ions in the solution

30

this solution process with water as the solvent is referred to as

hydration

31

as ydrated ions diffuse into the solution, other ions are exposed and are drawn away from the

crystal surface by the solvent

32

the entire crystal gradually dissolves and hydrated ions become unifromly

distributed in the solution

33

when crystallized from aqueous solutions, some ionic substances form crystals that incorporate water

molecules

34

these crystalline compounds, hydrates, retain specific ratios of water molecules and are represented by formulas such as

CuSO4 . 5H2o

35

heating the crystals of hydrate can drive off the wter of hydration and leave the

anhydrous salt

36

when a crystalline hydrate dissolves in water, the water of hydration returns to

the solvent

37

the behavior of a solution made from a hydrate is no different from the behavior of one made from the

anhydrous form

38

dissolving either form results in a system containing

hydrated ions and water

39

ionic compounds are generally not soluble in

nonpolar solvents

40

the nonpolar solvent molecules do not attract the ions of the crystal strongly enought to overcome the forces holding the

crystal together

41

liquids that are not soluble in each other are

immiscible

42

nonpolar substances are generally quite soluble in

nonpolar liquids

43

the only attractions between the nonpolar molecules are

london forces

44

the intermolecular forces existing in the solution are therefore very similar to those in

pure substances

45

liquids that dissolve freely in one another in any proportion are said to be

miscible

46

changes in pressure have very little effect on the solubilities of

liquids or solids in liquid solvents

47

increases in pressure increas gas

solubilities in liquid

48

when a gas is in contact with ther surface of a liquid, gas molecules can

enter the liquid

49

as the amountof dissolved gas increases some molecules begin to escape and reenter the

gas phase

50

an equilibrium is eventually established between the rates at which gas molecules enter and leave the

liquid phase

51

as long as this equilibrium is undistrubed, the solutibility of the gas in the liquid is unchanged at a given

pressure

52

gas + solvent ⇌

solution

53

increasing the pressure of the solute gas above the solution puts stress on the

equilibrium

54

molecules collide with the liquid surface more

often

55

the increase in pressure is partially offset by an increase in the rate of gas molecules entering the

solution

56

in turn the increase in the amount of dissolved gaas causes an increase in the rate at which molecules escape from the liquid surface and become

vapor

57

eventually equilibrium is restored at a

higher gas solubility

58

an increase in gas pressure casues the equilibirium to shift so that more molecules are in the

liquid phase

59

the solubility of a gas in a liquid is directly proportional to the partial pressure of that gas on the surface of the liquid:

henry's law

60

henry's law applies to gas liquid solutions at

constant temperature

61

when a mixture of ideal gases is confined in a constant volume at a constant temperature, each gas exerts the same pressure it would exert if it occupied the space

alone

62

assuming that the gases do not react in any way, each gas dissolves to the extent it would dissolve if no other gases were

present

63

the rapid escape of a gas from a liquid in which it is dissolved is known as

effervescence

64

increasing temperature usually decreases

gas solubility

65

as the temperature increases, the average kinetic energy of the molecules in solution

increases

66

a greater number of solute molecules are able to escape from the attraction of solvent molecules and return to

the gas phase

67

at higher temperatures, equilibrium is reached with fewer gas molecules in solution, and gases are generally less

soluble

68

the effect of temperature on solubility of solids in liquids is more difficult to

predict

69

often, increasing temp increases solubility of

solids

70

however, an equibalent temp increase can result in a large increase in solubility for some solvents and onlyt a

slight change for others

71

in some cases, solubility of a solid decreases with an

increase in temperature

72

the formation of a solution is accompanied by an

energy change

73

the formation of a solid liquid solution can apparently either absorb energy or

release enrgy as heat

74

during the formation of a solution solvent and solute particles experience changes in the forces attracting them to other

particles

75

befor3e dissolving begins solvent molecules are held together by

intermolecular forces (solvent solvent attaction_

76

in the solute molecules are held together by

intermoelcular forces (solute solute attraction)(

77

energy is requoired to separate solute molecules and solvent moecules from their

neightbors

78

a solute particle that is surrounded by solvent molecules is said to be

solvated

79

the net amount of energy absorved as heat by the solution when a specific amount of solute dissolves in a solvent is the

enthalpy of solution

80

thyou know tghat heating decreases the solubility of a gas, so dissolution of gases is

exothermic

81

in the gaseous state, molecules are so far apart that there are virtually no intermolecular forces of

attraction between them

82

therefore the solute solute interaction has little effect on the

enthalpy of a solution of a gas

83

energy is relreased when a gas dissolves in a liquid because attraction between solute gas and solvent molecules outweighs the energy needed to separatge

solevent molecules

84

Enthalpy of solution is negative when energy is

Released

85

Enthalpy of solution is positive when energy is

Absorbed

86

Energy is absorbed when solute particles becoming

Separated from solid

87

Energy is absorbed when solvent particles being moved apart to allow

Solute particles to enter liquid

88

Energy being released when solvent particles being attracted to and

Solvating solute particles