Chp 7 Solubility [COMPLETE] Flashcards
polar bonds
when bonded atoms have a significant difference in their electronegativities
what does polarity determine?
solubility
what will something polar be soluble in?
polar solvents, like water
what will something non polar be soluble in?
non-polar solvents, like hexane, propane, benzene, toluene, etc
how to determine polarity in simple molecules?
polar bonds:
non polar bonds:
O-H bonds are POLAR; the more OH, the more polar
C-H bonds are NONPOLAR; the more CH, the more nonpolar
polarity ‘truck’ method
- draw lewis structure, flat and far apart as possible
- draw arrows from least to most electronegative atom
- would truck be pulled out?
yes = polar
no = nonpolar
what does miscible mean?
soluble
polarity of water?
polar
solution
a uniform mixture of two or more substances
solvent
the substance in a solution that is present in a larger amount; usually a liquid
solute
the substance in a solution that is present in a smaller amount
saturation point
the point where the solvent can no longer dissolve the solute
unsaturated solution
the solution prior to reaching saturation point
saturated solution
the solution after reaching saturation point
concentration
amount of solute in a solution
what are the two ways that concentration can be expressed?
molality and molarity
molality (m) =?
moles of solute/kg of solvent
mnemonic/memory for molality
molality is before the solutution, solute goes into solvent so moles of solute/kg of solvent
molarity (M) =?
moles of solute/L of solution
mnemonic/memory for molarity
the bigger uppercase M, means dealing with bigger unit, L and overall big solution
what two things would the molarity formula help you determine?
- a SOLUTIONS concentration
- moles or grams of a SOLUTE, if you have the concentration or volume
which do we use for colligative properties?
molality
(s) subscript
solid or solid precipitate
(g) subscript
gas
(l) subscript
liquid
(aq) subscript
aqueous, dissolved in water
what is the definition of solubility rules?
The “rules” about which ionic compounds dissolve in WATER and which ones do not
solubility rule #1: SOLUBLES (memorize)
- group 1 metal cations
- nitrate (NO3-)
- perchlorate (ClO4–)
- acetate (C ₂H ₃O⁻ ₂)
- ammonium (NH₄⁺)
solubility rule #2: INSOLUBLES (memorize)
- silver (Ag⁺)
- lead (Pb2⁺)
- sulfide (S2–)
- hydroxide (OH–)
- dimercury (Hg22⁺)
- carbonate (CO32–)
- phosphate (PO43–)
if an ionic compound has both a soluble and insoluble..
it will be soluble, solubles generally trump the insolubles
what can happen when two different ionic compounds are dissolved together in water?
they could react with each other by doing metathesis
what is metathesis (double-displacement) reaction?
a partner swap
AB + CD –> AD + CB
A gets C’s partner, and C gets A’s partner
under what circumstance would the partner swap (metathesis) lead to the actual reaction? what is the full explanation so that you understand?
if either AD or CB are
INSOLUBLE in water; basically….
if you were to partner swap
AB + CD –> AD + CB
and either AD or CB ends up being insoluble, then the equation up there would exist as the reaction!!! if not then its not going to react together and therefore not partner swap and either dissolve or not dissolve based on the original thing
if regular positioning reactants are SOLUBLE then…
AB + CD –> A+(aq) + B–(aq) + C+(aq) + D–(aq)
they dissolve in their original order, all are separated with their pertaining charges
if regular positioning reactants (either or) are INSOLUBLE then…
AB(s) + CD(aq) –> AB(s) + C+(aq) + D–(aq)
means that the insoluble compound will stay together, and the soluble one dissolves with its pertaining charges
when writing reactions that involve dissolved compounds (aq) make sure that
they have their pertaining charges; ONLY FOR DISSOLVED COMPOUNDS
complete ionic equation is the same as
the partner swap equation; IF ACCURATE TO THE RULE THAT EITHER AD OR CB ARE INSOLUBLE
[EXAMPLE] COMPLETE IONIC EQUATION
NaCl (aq) + AgNO3 (aq)
this is already balanced but make sure that you balance the equation after you do a partner swap!
start with partner swap:
NaCl (aq) + AgNO3 (aq) –> NaNO3 (aq) + AgCl (s)
since Ag is an insoluble substance, AgCl is an insoluble, meaning it applies to the rule that if either of the products due to the partner swap are insoluble, then this equation/reaction exists
the reaction above is aka COMPLETE IONIC EQUATION
[EXAMPLE CONTD] TOTAL IONIC EQUATION
NaCl (aq) + AgNO3 (aq) –> NaNO3 (aq) + AgCl (s)
starting with complete ionic equation:
NaCl (aq) + AgNO3 (aq) –> NaNO3 (aq) + AgCl (s)
in WATER, anything with an (aq) will dissolve!! this means that ONLY the aq species in this reaction have to be written separate!!
split them; remembering that dissolved species will end up w their charges:
Na|Cl (aq) + Ag|NO3 (aq) –> Na|NO3 (aq) + AgCl (s)
resulting in; with their charges:
Na+(aq) + Cl–(aq) + Ag+(aq) + NO3–(aq) –> Na+(aq) + NO3–(aq) + AgCl(s)
the reaction above is aka TOTAL IONIC EQUATION
[EXAMPLE CONTD] NET IONIC EQUATION
Na+(aq) + Cl–(aq) + Ag+(aq) + NO3–(aq) –> Na+(aq) + NO3–(aq) + AgCl(s)
continued from total ionic equation:
Na+(aq) + Cl–(aq) + Ag+(aq) + NO3–(aq) –> Na+(aq) + NO3–(aq) + AgCl(s)
we cancel out everything that is the same on both sides of the equation
this leaves us with:
Cl–(aq) + Ag+(aq) –> AgCl(s)
the reaction above is aka NET IONIC EQUATION
what are spectator ions?
these are the things that get cancelled out during the process of getting the net ionic equation
so from the last example, the spectator ions would be:
Na+ and NO3-
what are the 4 steps to generate a net ionic equation? (memorize)
- create the partner switch first!! balance the equation by writing out the corresponding charges first, and then the subscripts, go from there to balance the rest (without the charges)
- use solubility rules to label using s, l, g or aq substances
- cut the (aq)s in half, separating cations from anions
* pertaining charges appear and subscripts turn into coefficients* - cancel out species that are the same on both sides
when do you balance an equation?
after the partner swap
are solids soluble?
in some liquids yes! just not in water, like the previous examples were based on!
what is the relationship between temperature and the solubility of a solid? what does this mean in high temp? low temp?
directly related
↑ temp = ↑ solid solubility
↓ temp = ↓ solid solubility
what is the relationship between temperature and the solubility of a gas? what does this mean in high temp? low temp?
inversely related
↑ temp = ↓ gas solubility
↓ temp = ↑ gas solubility
why is temperature inversely related to gas solubility? soda example?
gas molecules move faster as temperature goes up
When a gas is dissolved in a liquid, raising the temperature (hot) will increase the gas molecules’ speeds, which causes gas molecules to escape and leave the liquid fast
its why soda is served cold; the low temperature preserves the gas molecules CO2 to be dissolved in the drink, giving it the fizz
what is the relationship between pressure and gas solubility? soda example?
directly related
↑ pressure = ↑ gas solubility
↓ pressure = ↓ gas solubility
its why a bottle of soda is under pressure before opening, and why it loses it bubbles if left open
more pressure exerted, more dissolved the gas molecules are
what is Henry’s law and what is the formula?
in a sealed vessel containing dissolved gas, the gas’ pressure and concentration are proportional
concentration = gas pressure
formula:
PA = kH[A]
PA: gas’ pressure in solution
[A]: gas’ concentration in moles/L (molarity)
kH: constant that differs for each gas, solvent, and temp
what should be memorized about Henry’s law, if not the formula?
that whatever you do to the pressure, you do to the concentration
what are colligative properties? what are the 2 examples?
properties of a solution that are susceptible to change as you add more solute
example:
if you dissolve something in a liquid, the liquids freezing point changes by going down. basically it now requires lower temp to freeze, meaning its harder to freeze now
freezing point is a colligative property
example 2:
if you dissolve something in a liquid, the liquids boiling point changes by going up. basically it now requires a higher temp to boil, meaning its harder to boil now
solute and freezing point are:
inversely related
↑ solute = ↓ freezing point
↓ solute = ↑ freezing point
solute and boiling point are:
directly related
↑ solute = ↑ boiling point
↓ solute = ↓ boiling point
what actually causes solution’s boiling point to go up when you add a solute?
the drive to avoid decreased entropy
formula to calculate change in FREEZING POINT
ΔTF = –iKFm
ΔTF is the change to the liquid’s freezing temperature.
i is the Van’t Hoff factor
KF is the freezing point constant
m is the solution’s molality (moles of solute / kg solvent)
what is the Van’t Hoff factor? example?
a number that goes up as the number of molecules or ions in the solution goes up.
example 1:
NaCl dissolves into Na+ and Cl-
those are two things, so the i number would be 2
example 2:
Ca(NO3)2 dissolves into Ca2+ and two NO3- ions (bc of the subscript 2 that becomes coefficients, representing the amount)
those are three things, so the number would be 3
this would mean that bc 3 is the higher number, this would decrease the freezing point more
formula to calculate change in BOILING POINT
ΔTB = iKFm
ΔTB is the change to the liquid’s boiling temperature
i is the Van’t Hoff factor
KB is the boiling point constant
m is the solution’s molality (moles of solute / kg solvent)
dissolving glucose in water
it’ll dissolve but doesn’t produce ions so
1 mole of glucose added will only give you 1 mole of dissolved glucose
what is the connection between solute, boiling point, and vapor pressure?
↑ solute = ↑ boiling point = ↓ vapor pressure
what is Raoults Law used for and what is the formula?
used to determine the amount that a solutions vapor pressure will decrease when a solute is added
PA = ΧA x Ppure
Ppure: vapor pressure of the original solvent, when it’s pure.
ΧA: percentage of solvent in the new solution
PA: is the solution’s new vapor pressure
what is osmosis?
the flow of water from an
area of high concentration of water (low solute) to an area of low concentration of water (high solute), in order to BALANCE those areas’ SOLUTE concentration (by diluting the other side w all the water)
osmosis in terms of solvent and solute
the solvent will always flow
toward the side with a higher solute concentration
how does osmosis affect osmotic pressure?
when the water shifts to equalize the concentrations of both chambers, it changes the pressure above the liquid on both sides
what is osmotic pressure then?
the amount of pressure you have to apply to stop osmosis
osmotic pressure formula
Π = i (n/V) RT
(n/V) has units of moles/liter, meaning its molarity or concentration
n is the number of moles of dissolved solute;
i is the number of dissolved solvent molecules or ions that your
solute produces
this means n has to be multiplied by the number of ions the solute produces, if the solute is an ionic compound
DAT TIP: what is the preferred colligative property to use for measuring
high-molecular-weight molecules (1000 g/mole or higher)?
osmotic pressure
this is because it’s much easier to accurately measure a small change in osmotic pressure than to measure a tiny difference in
freezing/boiling point.
what will be the new boiling point when you mix two liquids with two different boiling points?
it will be the temperature between the two liquids that you are mixing
