Lecture 1 & 2 (Ch. 13): Solutions, IMF, Factors Affecting Solubility

Question 1

are solutions homogeneous or heterogeneous?

Answer 1

• homogeneous

- uniform mixtures

Question 2

which is present in larger/smaller amounts: the solute or solvent?

Answer 2

• solute: smaller amounts

- solvent: larger amounts

Question 3

dissolution

Answer 3

-solute breaks apart into ions or molecules

Question 4

crystallize

Answer 4

• when dissolved solute comes out of solution

- forms a solid

Question 5

solution equilibrium

Answer 5

-when rates of dissolution and crystallization are equal

Question 6

saturated solution

Answer 6

• soln is in equilibrium w/ undissolved solute
• contains max amount of solute for a solvent (at specific temp)
• if more solute is added, it won’t dissolve

Question 7

solubility

Answer 7

-amount of solute needed to form a saturated solution

Question 8

unsaturated solution

Answer 8

-contains less than max amount of solute (at specific temp)

Question 9

supersaturated solution

Answer 9

• contains more than the max amount of solute (at specific temp)
• not stable
• if more solute is added, excess solute crystallizes until saturation reached

Question 10

miscible

Answer 10

-mixes completely

Question 11

immiscible

Answer 11

• doesn’t mix significantly

- i.e. oil and water

Question 12

entropy

Answer 12

• increase in disorder (randomness)

- ∆S

Question 13

why do solutions form?

Answer 13

• due to entropy

- like dissolves in like (polar w/ polar, etc)

Question 14

intramolecular forces

Answer 14

• forces btwn atoms WITHIN a molecule
• (aka bonds within molecule)
• solid lines

Question 15

intermolecular forces

Answer 15

• IMF
• btwn atoms of SEPARATE molecules
• dashed lines

Question 16

london dispersion forces

Answer 16

• movement of electrons within the electron cloud creating instantaneous dipole (temporary partial charge)
• present btwn all molecules

Question 17

dipole

Answer 17

-distribution of electrons, one end has excess(δ-), the other electron deficient (δ+)

Question 18

when do london dispersion forces increase?

Answer 18

• with increasing molar mass (more e- to distort)

- the more linear the shape (more contact points)

Question 19

dipole-dipole

Answer 19

• attraction btwn neutral polar molecules

- permanent dipole

Question 20

h-bonding

Answer 20

• extra strong dipole-dipole forces

- H atom bonded to FON attracted to lone pari of another FON atom

Question 21

ion-dipole

Answer 21

• btwn ions and partial charges (dipoles, δ) of polar molecules
• exist when ionic compounds dissolves in polar substance

Question 22

list the order of strongest to weakest IMF

Answer 22

• ion-dipole
• h-bonding
• dipole-dipole
• london dispersion

Question 23

how do solutions form?

Answer 23

-forces and bonds are broken and new forces created

Question 24

solvation

Answer 24

• when solute is surrounded by solvent

- i.e. hydration

Question 25

hydration

Answer 25

-special case of solvation bc water is the solvent

Question 26

solute-solute interaction

Answer 26

- must be broken, requires energy - endothermic (+) - i.e. ionic bonds

Question 27

solvent-solvent interaction

Answer 27

- must be broken, requires energy - endothermic (+) - i.e. h-bond

Question 28

solute-solvent interaction

Answer 28

- must be formed, gives off energy - exothermic (-) - i.e. ion-dipole

Question 29

which is favored in solution formation: exothermic or endothermic and why?

Answer 29

- exothermic bc solute-solvent particles are highly attracted to each other - not endothermic bc entropy is being counteracted by small ∆Hsoln value (if it's too +, no soln forms)