Solutions and Solubility

Question 1

solution

Answer 1

a homogenous mixture

Question 2

homogenous mixture

Answer 2

has uniform composition

Question 3

What are MCAT solutions generally?

Answer 3

solids dissolved in liquids

Question 4

Saturation and units

Answer 4

how much solute is dissolved

g/L

Question 5

When will a precipitate form?

Answer 5

adding more solute to an already saturated solution

or decreasing the solubility of a solution

Question 6

When is a solution saturated?

Answer 6

a solution is saturated when concentrations of reactants are equal to Ksp

Question 7

Ways to decrease the solubility of a solution?

Answer 7

through the common ion effect or by changing temperature/pressure

Question 8

Do most dissolutions change temperature or pressure?

Answer 8

yes. most solutions are endothermic and require heat, which lowers the environment’s temp.

Most dissolutions also increase pressure.

Question 9

supersaturated

Answer 9

more than max solute is dissolved in solution

Question 10

electrolyte

Answer 10

ions in solution that can conduct electricity

Question 11

What does a higher temperature do to solubility of an ionic compound?

Answer 11

increases solubility

most dissolutions are endothermic and require heat

Question 12

What does a lower temperature do to solubility of an ionic compound?

Answer 12

decreases solubility

most dissolutions are endothermic and require heat

Question 13

Relationship between solubility of a gas and temperature

Answer 13

Lower temperature makes the gas less soluble

Gas has less energy to escape the solution

Question 14

Alkali metals solubility

Answer 14

always soluble in H2O

Question 15

What molecules are always soluble?

Answer 15

nitrates, chlorates, and acetates

Question 16

Halides solubility

Answer 16

always soluble unless with Ag, Pb or Hg

Question 17

Halide atoms

Answer 17

F, Cl, Br, I

Question 18

SO4 2- solubility

Answer 18

always soluble expect with Ca, Sr or Ba

Question 19

What molecules are generally insoluble?

Answer 19

carbonates, phosphates, S2- and sulfates

except with alkali metals that are always soluble

Question 20

Are oxides generally soluble or insoluble?

Answer 20

generally insoluble

except for with Ca, Sr, Ba or alkali metals

Question 21

Molarity

Answer 21

M

moles of solute / liter of solution

Question 22

Molality

Answer 22

m

moles of solute / kg of solvent

Question 23

For water, one liter equals

Answer 23

one kilogram

Question 24

For water, one mL equals

Answer 24

one gram

Question 25

When do we use molality?

Answer 25

when discussing colligative properties

Question 26

colligative properties

Answer 26

properties changing solely with concentration of a solution ex: adding salt to H2O lowers freezing point

Question 27

Normality

Answer 27

number of equivalents / liter of solution

Question 28

When do we use normality?

Answer 28

in acid-base chemistry the equivalents are H+ or OH- ions

Question 29

How can we get molarity from normality of an acid?

Answer 29

N = M(acid) * H+ in acid molecule

Question 30

How can we get molarity from normality of a base?

Answer 30

N = M(base) * OH- in base molecule

Question 31

What does Ksp tell us?

Answer 31

how soluble something is

Question 32

Relationship between Ksp and solubility

Answer 32

higher Ksp = more soluble

Question 33

What is Ksp formula generally?

Answer 33

= [anions] [cations] *solid reactant and pure water are not included in formula

Question 34

When Q>Ksp what happens?

Answer 34

a precipitant forms maybe not right away, solution could be supersaturated for a little

Question 35

When saturated what rates are equal?

Answer 35

rates of dissolution and precipitation, ie. forward and reverse reactions

Question 36

common ion effect

Answer 36

solubility of an ionic species decreases when one of its component ions is already present in solution

Question 37

How does common ion effect theoretically work?

Answer 37

since some reactant is already present, less solute can dissolve before Ksp is reached means that we have less solubility shifts reaction towards the solid reactant

Question 38

Where do we see the common ion effect?

Answer 38

in acid base chemistry ex: having a basic solution (more OH-), might make Pb(OH)2 less soluble

Question 39

Can you shift a dissolution towards the reactants?

Answer 39

sure can use a coordination complex around a metal to remove ions from the solution

Question 40

Weak electrolyte

Answer 40

does not produce many ions when dissolved in solution