Solutions

Question 1

define a solution

Answer 1

one or more substances (solutes) mixed at the molecular level (dissolved) in a medium (solvent, usually liquid)

Question 2

two properties of a solution

Answer 2

• uniform mixing
• constant composition throughout

Question 3

percent A by mass =

Answer 3

mass of solute A/mass of solution x 100

Question 4

parts per million (ppm) A =

Answer 4

mass of solute A/mass of solution x 10^6

or

moles of solute A/moles of solution x 10^6

Question 5

mole fraction (Xa) =

Answer 5

moles of solute A/moles of solution

Question 6

solutions that obey Raoul’s law are called

Answer 6

ideal solutions

Question 7

Colligative properties

Answer 7

solution properties that depend on the concentration of a solute, not its identity

Question 8

freezing point depression

Answer 8

solutes lower freezing point of the solvent

Question 9

boiling point elevation

Answer 9

solutes raise boiling point of the solvent

Question 10

vapour pressure lowering

Answer 10

solutes decrease vapour pressure of the solvent

Question 11

osmotic pressure

Answer 11

pressure that must be applied to a solution to prevent osmosis from a sample of a pure solvent

Question 12

how do non-volatile solutes act on the vapour pressure of the solvent?

Answer 12

they decrease it

Question 13

Raoul’s law for non-volatile solute:

Answer 13

P = XP^0
P - vapour pressure of solvent in solution
X = mole fraction of the solvent
P^0 = vapour pressure of pure solvent

Question 14

what needs to occur for substances to form a solution?

Answer 14

the solute-solvent interaction has to overcome both solute-solute interactions and solvent-solvent interactions

Question 15

volatile

Answer 15

something that can evaporate

Question 16

what is the difference between the effect of a volatile and non-volatile solute?

Answer 16

with a volatile solute, both the solvent and solute contribute to vapour pressure

Question 17

P total =

Answer 17

P sub 1 + P sub 2

Question 18

osmosis

Answer 18

net flow of solvent through a semi permeable membrane from a dilute solution to more concentrated solution

Question 19

semi-permeable membrane only allows

Answer 19

solvent to go through, not solvent

Question 20

osmotic pressure

Answer 20

pressure that must be applied to the solution to prevent osmosis from a sample of pure solvent

Question 21

how do you signify osmotic pressure?

Answer 21

pi

Question 22

equation for osmotic pressure

Answer 22

pi = MRT
pi - osmotic pressure
M - total molarity of all solutes
R - gas constant
T - temperature (K)

Question 23

how do you know which value of R to use?

Answer 23

whichever one the units cancel out for

Question 24

dissociation of 0.1M NaCl
dissociation of 0.1M CaCl2
dissociation of 0.1M glucose
state the osmotic pressure for all

Answer 24

Na+ and Cl-
Ca2+ and 2Cl-
stays same
0.200M, 0.100, 0.300M

Question 25

state van’t Hoff’s factor

Answer 25

i = moles of particles in solution/moles of solute dissolved

Question 26

substances with —– ——– —– form solutions

Answer 26

similar intermolecular forces

Question 27

formula for solubility

Answer 27

solubility = k P

P - partial pressure of gas over the solution
k - Henry’s Law constant - depends on gas and solvent (usually H2O)