Unit 2: Gen Chem; 5,6,7,8,9,10
estimating p values
*from [] to pH: (n-1).(10-m) -> to log *from pH to [] (n+1).(10-m) -> to undo log -M*10^n (think M to the n) -Me^n (m=mantissa, n=exponet) *1e-9 -> ph 9 , this happens when the mantisa is 1 (still inverse the exponent) If n(exponent) is negative then the answer is positve, when n is positive the answer is negative To remember that m always subtracted think the bigger number should be subtracted by 10 always to remember to subtract to go to pH remark you have to -logH to get to pH (just for mem), also remember that n tells you whether answer will be positive or negative (always pop of its sign when using -log)
Analyzing Keq
-A large positive exponent with value bigger then 1 says that rxn will almost go compelty forward (more products than reactants) -A alrge negative exponent that makes overal value below 1 means that reaction will favor going to reactants (bottom heavy) and only a small amount of reactants are converted to products -Use 1 as reference bc in idea world [P]=[R]
litmus paper
-Blue Base -Red Acid
phase diagram
-Critical Point: unable to tell btw lig and gas, and both densities are equal, above this heat vapor=0 -Triple Point: all phases exists -gas phase: favored in low P and high temps (temp gives ability to escape) -Liq phase: low temp and high Pressure (pressure keeps it from escaping) -Solid: moderate/low temp and pressure think endergonic going up exothermic going down (solid more stable)
solubility constant (Ksp)
-Depends on temp and pressure @ predetermined set, also remeber the solubiltiy depends on enthalpy and entropy, -solids and liq dont appear in equi constant and in solutions thats what we usually get -Ksp ↑ with non-gas solutes with ↑Temp -Ksp ↓ with gas solutes with ↑Temp (↑Temp makes KE bigger and react liq escapes to gas) -Higer Pressurs favor dissolution of gases so Ksp also higher (forces them back into liq to be dissolved and harder to reach BP bc ambient higher) -only really care about anything attached to NO3 or Na, Look at stoich not know what coefficent value to place in [ ], when given two cmpds and asked about the mixture of them both together that would form a product just use thier [] dont have to worry about common ion effect if theres no common ion and if they give you the value of Ksp ex NaBr + AgCl mixed will percpitate form if Ksp of AgBr is x, when mixed that product will be AgBr
Free energy diagram
-Gibbs Free E is the differences in E between products -reactants, and if products is low then negative amt forms and exergonic -If +∆G then Endergonic, E is absorbed -If -∆G then Exgeronic, E released -the Transtion state is the highest point, multiple big bumps tells us how many steps/transition states -The difference between transition state and reactant: Ea of forward -The differnce btw transition state and product: Ea of reverse rxn Thermo and kinetic should be sep, it is possible to change the free E of the products can be raised or lowered which then changes ∆G and Ea
Special Thermodynamic Processes
-Isothermal: temp is constant so U is also constant and doesnt change, temp and U are directly proportional -Adiabatic: no heat is exchangedso Q=0 but W is now W done ON the system (not by, just for this), bc when moving Q over the negative signs on both sides cancel out -Isobarric: P is constant, but bc P doesnt ∆ anything and amount of Work doesnt change between intital and final (looking at graphs) - Isovolumetric: no change in volume so no work done
x-gonic v x-thermic
-It is possible for rxn to be endothermic and still be spont (as long as entropy is poistive and high temps) or exergonic -BUT NOT possible for rxn to be exothermic and non-spont (endergonic) -gonic just means spont or non spont -be sure to look at how T∆S compares to ∆H, that relationship tells you the gonic part -remeber this doesnt invovle rate, so spont can be slow or fast, and the major product may just be the kinetic product bc activation E is too high to reach thermal product (due to hinderence etc)
Liquid-Solid Equilibrium
-Melting: everything has motion even solids, as temps increases vibrational motion increases (when heat applied) and solid breaks down to liq and gain entropy -Liq to solid: Freezing or Solidifcation, happens at freezing point, same concept as above
Gibbs free energy and spontaneity
-Moving TOWARD equi positoin, then you are decreasing ∆G and is spont -Moving AWAY from equi, then you are increasing ∆G and is non-spont
Free Energy equations
-Q is at any [] -K is at equi position for the standard state In ∆Grxn (not standard- MIDDLE FORMULA) -if Qor Keq is less then 1-> ln value will be NEGATIVE and ∆G will be negative (spont) -if Qorkeq is greater then 1-> ln value will be positive and ∆G will be positive (nonspont) remebr ln is natural log function basically is log2.7(x)=y which is 2.7^y=x, and bc of this the smaller X is then more negative (think of it as graph, anything above 1 is positive, anything below 1 is negative)
Factors that Affect Reaction Rate-only ways to increase k
-Reaction []: bigger [] the greater collision rate (A increases in arrehenius) so rxn rate will too (in gases partial pressure=[]) -Temperatre: rxn rate increases with temp, bc temp is measure of KE the more KE then more chance it has to overcome Ea, in BIO systems increase temp by 10 then rxn rate is doubled but becareful with denature -Medium: polar solutions usually better bc their diploe induces diploe in bonds to stregnth/weaken, some perfer aq some like non-aq (DMSO and ehtanol) -Catalyts: increase rxn rate w/o themselves being consumed, they lower Ea ONLY by interacting with the reactant to stabalize the intermediates or to adpsorpt (adhese/keep in place) the molec, they can also increase the frequency of collisions, change the orientation of reactants etc, THEY DO NOT TOUCH FREE E or Keq or equi they just help to get faster to equi position, they lower Ea to BOTH forward and reverse rxn by the same factor (Forward lowered by 2 then so is reverse) -Homogenous catalysis: catalyst in same phase (solid, liq gas) -Heterogenous catalysit: catalyst in differnet phase -catalyst change the rate (K) but not the Keq bc thats equi
Gas-Solid Equilibrium
-Solid to Gas: sublimation -Gas to Solid: Deposition
Standard Conditions v Standard Temp and Pressure (STP)
-Standard Conditions: 298K (25C), 1M, 1atm this gives most stable form of product (standard state) -STP: 273K (0C), 1M, 1atm used for ideal gas calcs -Common Standard States: H2(g), H20(l), NaCl(s). O2(g), C(s, graphite) -the º tells the process is in standard conditions and is the zero point for thermo and at equi
systolic pressure and dystolic
-Systolic: the pressure in your blood vessels when your heart beats -Dystolic: the pressure in your blood vessels when your heart rests between beats think SD-> sunny d makes healthy
Chemical Kinetic theories
-collision theory -transition state theory
Gas Diffusion
-heavier gases diffues slower bc the light ones havea higher average spped -all particles have the same KE at a temp, then particles with a greater mass travel at a slower speed -Defusion is when gases mix with eachother while effucion is pushiong gases through small wholes udner pressure (both utlize the same Urms and equation in pic) -use use Urms to define avg kinetic speed of a particle (sqrt3RT/M)
Key things to remebr about keq
-solids and liq not in it -Keq is a constant at a CERTAIN TEMP, if ∆temp then Keq ∆ -larger Keq, the farther to the right the equi poistion (more prducts then react (P/R)) -If Keq is written for a certain direction, then the Keq for the revesre is just the 1/Keq
Heating Curves
-the heat added or removed in phase change does NOT change the temp bc temp is related to KE and KE doesnt chnage only the potential E ∆ -Temp wont change until all subtances have been converted to next phase (bc at equi state when in phase change) -KE doesnt ∆ bc although you gain microstates and freedom to move when adding heat, you must compensate for the way you can move by having less amount of times you move, so bc of that KE is the same at any state (liq or solid) at a temp in phase change -U changes bc the stabiltiy of the cmpd from its bonds to eacohter ∆ when increasing temp as they can move more, so more likely to rxn when in liq or gas form -to go btw phases (q=ml) to go to certain temp (q=mc∆T -+∆Hfusion bc heat added to go from S to L - (+)∆Hvaporization bc heat added to go from liq to gas
At constant moles in ideal gas law
-the subscripts refers two states of the gas, at STP and one at actual temp and pressure -assumes the number of moles stays constant -if you rearrange it to calc the cahnge in volume (v2) then you can find density by: Density=mass/volume2 -V1=22.4(per mole you have) (so as moles increase so does the volume by 22.4*mole) -use this formula input STP conditions in the 1 subscript and the new values that are not at STP in V2 (do this as needed not always, only do this when missing subscript 2 values with no reference) -can use this formula to look at changes seen btw condtions outside STP as well
Strong Acids and Bases
-they completely discoc. into their components, so forward rxn (not really equi), bc of that [SA] will discoc into [SA]=[OH-] (it will disco into its CB) -bascially, to find pH just -log[SA] bc autoionzation is negligible -have a pka~1 (closer to 1 stronger) -SA leads to more stable CB (which is why forward rxn no equi) Note: autoionzation is negligible if the [SA] IS GREATER than 1e-7 M (so like 1e-2), BUT if near it then not negligible -higher Ka stronger acid (lower Kb) -lower pKA stronger acid (higher pKb) For bases: just think opp of SA -HF is a weak acid despite being so electronegtaive (bc of its ka bc HF bond E is greater then the E of F- being alone) Ex: HI,HCl, HBr, H2So4, HNO3(nitric) , HClO4 (perchloric) -SA leads to very weak CB
boiling point elevation
-when solute +solvent BP raised (Vapor P lowered) -BP is temp where Ambient P=Vapor P -if Vapor P lower than pure solvent than more E needed to make Vapor P =Ambient and done by increasing temp (elevating boiling pt) -Vapor P is the P to turn liq into gas and if vapor P decreased bc more blocked from turning into gas with increase solute then more E needs to be inserted to make equal to ambient -th answer given here is added to the original temp so be sure to note ∆T or new boiling pt (Old+this value)
solution equilibrium
1) When 1st adding solute, no intial present so dissoluitoin is favored (rate limiting) -Ksp>IP so unsat and dissolving 2)When you add more and [solute] appraochas to be equal molar solubility used in Ksp (dissolution rate lowers and periptation rate increses closer to equi) -Ksp=IP, saturated and at dynamic equi 3)When you add past the molar solubility/the [] at sautration -Ksp<IP, super saturated and percipate forms IP is the [] at any [] not at equi
Experimental Determination of Rate Law- Common Mistakes
1) this is done exp, cant know if dont know change in [], remember rate is Molarity/seconds and molarity is [] based and rate is proportional to [] or reactants only (not product) 2) Order of rxn are not stoich based, they are determined exp, only time when stoich is same as order if just one step (coefficents will be order) and if mech given including rate determing step is indicated (conicidence) 3) Mistaking Keq for k, Keq has product in it but in rates we dont care about product we only look at reactant 4) using the equi consat expression (ICE tables) for rate, again this is product and reactant based but we only care about rate of reactant k: is only a constant as a set temp, Ea, and collision freq (arrehnius)
Reaction Orders
1) zero order: happens when A^0 B^0 etc when no matter how much [∆] there is the rate wont change, to change this only way to do so is with catalyst and or increase temp 2) first order: rate is directly proportional to ONLY one ∆ in [reactant] that by doubling that reactant doubles the rate (rate=kA^1), common in radioactive decay, this means rxn begins when molec changes by itself doesnt need any env ∆ or additional chemical rxns to help it (its indepednet) 3)second order: k=A^2 or k=A^1*b^1, this means that there must be a physical collision btw sepcifc reactants Check out graphs if think need it
Boyles Law
A principle that describes the relationship between the pressure and volume of a gas at constant temperature
spontaneous reaction
A reaction that will proceed without any outside energy -spont doesnt mean it will happen quickly or go to completopion it just means enrgetically favorable, but adding E can kick start the rxn and the remainder of the rxn will happen spont (match, nothing happens alone but when thermal E as friction added the match will continue to burn) , doesnt need any more E once Ea is supplied -thermal E is friction, it is a form of E transfer -also think of how enzymes help increase the spont rxn rate by lowering Ea -some rxns dont go to completion but may settle at lower E state of equi, many rxns can go to completion but a lot just simply go to equi -coupling can also make a nonspont rxn spont
Amphiprotic
A species that can either accept or donate a proton. (gain or lose p+) -Ex water, and usually CB of plolyvalent acids (H2SO4->HSO4-), and species that acts as BOTH oxidation and reducing agents, aa at zwitterform -Note: amphiphatic has phobic and Phyllis regions -ampphipoheteric: acts as acid and base (think phot cause do both) -amphiprotic (think cna add or remove H proton) both mean say just idff term based on lewis/brosted
Acid/Base Definitions
Arrhenius-needs Aq solution -Acid: anything that discoc to excess H+ -Base: anything that disoc. to excess OH- (H20) Bronsted-Lowry: does not need Aq -Acid: H+ donor (H20) -Base: H+ acceptor Lewis acid: looks at lone pairs and coordinate covalent bond formation from them (make complex ion-acid/base) -Acid: e- pair acceptor (Acid Accept) -Base: e- pair donor Lewis most inclusive, Browsted, Arrenhenius (can't go down but can go up) -when hear coordinate think acid/base
Vapor Pressure Depression
As more solvent is increased the vapor pressure of solution decreases, Vapor P is the pressure to move to turn into gas from gas onto solution (technially is the P gas exerts to stay into liq but if gas isnt puttin much P to stay in liq then can evap(low then allows evap) -think as more solute molec add it blocks the solution molec from escaping into gas (evap) so Vapor P os pure solute lowered but condesation is not blocked (gas to liq) bc it can just be added on (like another top layer) -this law/equation only true if attraction btw diff molec is equal to attraction btw the same in pure state -lowering of Vapor Pressure (from adding solutes) results in a need for a higher temp to match atm P aka start boiling and evap (higher boiling pt)
Experimental Determination of Rate Law
Basically look at how change in [reactant] effected if any change in [product], any change in reactant [] that led to change in product [] can be attributed to the change of the reactant [] -do this exp by looking at table and holding reactant constant and looking at how the other reactant was changed and seeing if there are any change in the products -∆ in [Reactant]^x=∆[Rate] and x is the order in the rxn rate *Ex: if reactant [] changed by 4x then 4 and if product changed by 4 as well then 4^1=4 and that reactant that would change would have x^1 in the rate expression -Do this for all reactants to see which is in the rate law -Be careful with the [] product be sure to look at exponents especially if negative exponents, if negative exponets gets lwoered by one that means the [] product was increased by 10x (a power/magnitude) -Also, the changes in [] dont all have to be identical can use any trial at any point as long as one is held constant and other is changed (Doesnt matter where in table you choose to compare) -After finding this you can match it to rate order if needed
law of mass action
Basically, to find keq its [products] over [reactants], with the stoich coefficents as the exponents of the []. (Keq tells us poistion of equi at temp) -LARGER more far to the right it is -If Keq is written for a certain direction, then the Keq for the revesre is just the 1/Keq -solids and liq dont appear in this -at equi rate of rate(form products)=rate(form react), aka Kf=Kr -to find Keq can also do Kf/Kr=Kc=Keq bc rate of forward/rate of reverse is equal to being in the middle of them both (equi) -although rates are equal, the [] of each reactant can be different -if rxn has more then one step, can find Keq by multiplying the Kf(step1)*kf(step2)/kr(step1)*kr(step2) which also equals the Keq [] seen in pic -with this can find rates of reverse and forward if gien Keq -Keq tells us the [] needed to get to equi
complex ion formation and solubility
Complex ion is usually a metal (cation) bonded through coordinate colvanet bonds with an e- pair donor (ligands) -the Kf(formation of complex)>>>>>Ksp -Ex: Hb, carbon dioxide, carbon monoxoide, coenzymes (org), cofactors(non-org) -Inorganic Complex ions: vibrant distinct color -if central cation is bonded to the same ligan in multiple places then considered a chelation and they use large org ligands that can double back to make those multiple places -the forming of compex ions increases the solubility of a salt in the solution (bc engagnes in more polar bonds so able to engage in more dipole) -Kf is the new Ksp made after multiple coordinate covalnet bonds made, they from to become more soluble bc as more Ag (proudct of Ag-Cl) used up to form complex then equi shifts more to the right to make more complex ions -when u hear coordinate think acid/base bc they do this readily
Arrhenius equation
Continues on with collision theory -the frequency factor is basically how often do molcues collide, so bc in eq, the more often they collide the faster the rxn, frequency factor also depends on [] so more [] the more frequency -the negative exponent means that as it decreases it becomes less negative and closer to 0 (gets bigger), bc Ea on top the smaller the better (less E needed to overcome) and the greater the temp (bigger denominator so smaller exponent) the faster -Overall: more frequently collide, smaller Ea, increase concetration, and increase temps causes faster rxn rate
Diffusion and Effusion
Diffusion: going through membrane Effucsion: going through small whole under P BOTH SLOWER with large molec and use same equation M is molar masses
dilution equation
Dont forget that the V2 will be V1+any additional L added Ex: 1ml stock mixed with 1ml of X then V2 will be 2ml V1 will be 1ml -when doing muliple dillutions then need to use the M2V2 to plug into a new M2V2=M3V3 -the last V will be the final volume u have in the solution -be careful with multiple dillusions they are sneaky, they will be the commerical-> stock -> what was used in the exp (which V3 will be the amt of stock used + any addaitioanl things added)
Heat (Q)
Energy that transfers from one object to another because of a temperature difference -if Q absorbed: endothermic (+Q) -If Q released: exothermic (-Q) Defined as Joules or cal (1cal=4.184J) ****At constant Pressure, Enthalpy(H)=Q******* q=mc is the heat capacity
Spontaneity of Dissolution depends on
Enthalpy and Entropy BOTH Ex -when NaCl and H20 mixed, the Na-Cl bonds must and Hbons btw water molecules are broken (endothermic) and bc H+ then they can interact with Cl- and then the partially negative 02 (from dipole) interact with Na+ and this orderly solvation layer (this is exothermic but endothermic from earlier> exothermic from this so overall endo) -Breaking the Na-Cl bonds from lattice results in more microstates (+∆S na-cl, disorder so freer to move) for the Na-Cl but for water, it becomes MORE restricted (-∆S water) bc now has to interact with ions and then, at the end +∆S(nacl)>-∆S(water) so overall +∆Srxn -overall bc of low +∆H and high +∆S then in ∆G=∆H-T∆S is -∆G and spont and endothermic
Entropy (∆S)
Essentially how some form of E(chemical, thermal, PE) goes from be localized or concetrated to being dispersed -2nd law thermo says: E spont disperses from being localized to becoming spread out if not blocked from doing so (W must be done to [] it, and that consumes lots ofE) -Basically, a measure of spont E dispersal at a certain temp -Formula: Q is in reversible rxn of heat gain or loss -Units: Joule/mol*k -When E leaves the system, entropy increases (more room for dispersal) -When E comes into system, entropy decreases (more crowded) -Can apply hess law of product-reactant to find ∆Srxn
Kinetic and Thermodynamic Control of Reactions
Kinetic Product: faster to form, less E needed to make this product but product is less stable, lower E transtion staes Thermo Products: longer to form, more E needed to for the product but product is more stable, higher E transtion states -Common in Orgo Rxns
Aqueous solution rules
Know first 2 for sure, but dont need to memorize -Also know that Pr2+ and Ag+ are exceptions -sodium and nitrate ions [] that are part of a bigger cmpd are the same as the other element that made them ([NaX] is really [X]), transition metals count in molar solubility -Only time to worry about nitrates (No3-) is in oxidation reduction bc they are oxidants/oxidzign agents, in all other cases just focus on the cation that is invlved with it
Lewis base and acid and brownstd lawry acid/base
Lewis: not always H can be lone pairs -Acid: e- pair acceptors (lewis Acid-Accpetor) -Base: e- pair donor Browsted-Lowry: H involved -Acid: anything that donates H+ -Base: anything that recives/accepts H+
Gas-Liquid Equilibrium
Liq-Gas equi: -Liq to Gas: boiling, Evaporation, Vaporization, Endothermic -if liq molec gets enough KE to leave the liquid it can turn into gas (evaporization), if given enough E liq will evaporate -As liq loose high E particle the temp decreases and go to lower E state -this is endothermic with the heat being supplied by the liq itself -Boiling: type of vaporization in which all the volume of liq turns into gas, happens when Vapor Pressure(pressure gas exerts on liq to keep it from escaping)=Outside Pressure -Vapor P increases and temp increases bc more molec can have enough E to turn into gas which means P increases Gas to liq: condensation -seen at low temps and high P (particles slow down and pressure pushes them back into liq form)
Phase Changes
Liq-Solid Equi: -Liq to solid: Freezing or Solidifcation -Solid to liq: Melting or Fusion (fuse to booze) -Use heat of fusion Liq-Gas equi: -Liq to Gas: boiling, Evaporation, Vaporization, Endothermic -Gas to Liq: Condensation -Use Heat of Vaporization Solid-Gas Equi: -Solid to Gas: sublimation -Gas to Solid: Deposition
Molarity and normality
Mn=N Molarity=mol/l -used for solvent not total solutoin
reaction quotient (Q)
Q tells us where the rxn is in terms to equi, meaning is it past or getting close to it, serves as a comparision, uses same formula for Keq but [] are not a consant [] they are the [] at that time you are looking at -once at equi, the movemnt away eitehr forward or reverse is nonspont, things move spont to go to equi -Note: spont doesnt mean it will happen quickly or go to completopion it just means enrgetically favorable, but adding E can kick start the rxn and the remainder of the rxn will happen spont (match, nothing happens alone but when thermal E as friction added the match will continue to burn) , doesnt need any more E once Ea is supplied
Reaction Quotient and equi
Q<Keq --> forward rxn not reach equi yet: -more reactants then products, the forward rate of rxn is bigger than reverse to get to equi Q=Keq ---> at equi -react and products are at their set equi [] (doesnt have to be equal to eachother) and rate of forward and reverse are equal Q>Keq--> gone past equi position -more products than reactants so need to go back to reactants, reverse rate is greater to consume products to make more react -any move from equi once reached is nonspont, to get to equi is spont
Enthalpy (∆H)
The heat of a system at constant pressure** +∆H means endothermic (heat added) -∆H means exothermic (heat lost) To measure use hess law of heat of formation/rxn -Standard heat of formation (∆Hºf): enthalpy needed to produce one mole of cmpd from reactants in standard conditions (298K) -Basically tells us the ∆H needed to create this cmpd
mole fraction
The ratio of the moles of solute in solution to the total number of moles of both solvent and solute
Common Ion effect problem
Think of them as ice tables, -with the added common ion being the change of +[y] -then if x very small (molar solubility) can negate the x to where its just Ksp=[x other][x-ion +change] to Ksp=[x other][change]
Equi calcs
To not have to use the ICE table, if the Keq has a large negative exponent, then any change to the orginal reactant [] would be neglible and can cancel it out so just use the [] given and not the actual x- etc Ex:intial 1M of A with Keq=10e-12, then x^2/(1-x) turns into x^2/1 -In equi calcs, assume product [] are equal in keq which is why we x^2 it This doesnt apply it keq is 1/2 expoents away from having a total of 1 (100 OR 1000), or if [react] is 1/2 magnitudes away from the change ICE: INTIAL -CHANGE=EQUI -Remember at equi its at its min E state-, the minus goes to the reactantd and = to the products onyl when reaction will run forward (Q<K), but when K<Q its the opp the neg will be on products and +x on reactants Solids and liq not part of equi only aq and gas
Phase Change Overview
are reversible and equi will eventually be reached at any temp and Pressure in isolated systems and so the rates of forward and reverse rxns will be the same (Ice abs heat from liq but liq loses heat and freezes), -in a closed container with equi, gas and water will be at equi (plastic water bottle, water will gain KE to turn into gas but gas may losse KE and turn into liq), and number of liq and gas becomes constant (not same)
Arrhenius equation and orders
arrhenisu gives us the rate constant (how likly to react) -if s^-1 -> 1st order (when plugged in the Molarity from the ONLY [sub] will provide the M in the rate) -if M^-1 * s^-1 --> 2nr order (need to cancel one M out) -M*s^-1 -> 0th and only depends on the rate and no substarate so needs to supply the M Keq is not K, K is arrhenius based and wnats the rxn to happen regradless, Keq is equi
gases
behave similariy and only have LDF and are comrpessible -measured in torr, 101 kPa=1 atm=760 torr=760mmHg -in a barometer when the exter atm > intenral weight inside tube then the mesure risese -in a baramoter when the exter atm < internal weight inside tube then the measure shrink -when using gas constant, make sure you use STP (273) NOT standard conditions (298) (think stnadrd like standard kalvin) Standard Conditions (298)> STP (273) -One mol of ideal gas occuipes 22.4L at STP****
constant-pressure calorimetry
calorimetry where the pressure stays constant during the process eg coffee cup calorimetry -can apply Qor H=mc∆T and ∆U=Q-W
constant-volume calorimetry
calorimetry where the volume stays constant during the process eg bomb calorimeter (pick is gold) or decompostion vessel (think bombs explode bc volume cant cahnge and they then decompsoe shit) and since insulted then just Q=∆U and ∆Uinbomb=∆U water surrounding vessel aka Wdone by the bomb=W done on water (-W) OR qsystem=-qwater (which is just mcat) -Content in decompostion vessel is ignited and combustion happens, but bc W=P∆V no work done, and bc insulted can find q rxn -allows us to find heat of comubstion/rxn bc qsystem(vessel)=-qsurrounding (water) -adbiatic process
Calculating density of a gas from ideal gas law
can do this bc density is just mass over volume so find mols and convert it back to mass bc g of orginal/molar mass=mol then which is then all equal to PM/RT (pressure *molar mass/RT) , -also remeber 1 mol of ideal gas occupies 22.4L at STP, so once find volume just dviide mass by volume just found -if dont know molar mass but know desntiy at STP: Molar mass=density at stp* (22.4L/mol) think how L cancel out to give you g/mol (V1 is 22.4 per mol) think PM =density (denseer at night bc ate)
Real gases
deviate from ideal behavior under high pressure and low temperature conditions Ideal gases are opp in which real gases have intermolc forces and have v -at moderalty P normal temp Volume is less then expected (think normal less then), BUT AT extremely high temps HIGH p they volume is greater then expected (lower temp lower expectedmolec pushed togerther closer and attraction takes hold but at, higher temps higher then expected) -think follow the At lower temps they also tend to move less and inermolec force icnreases Lower P but EXTREME Temps -closer to BP the less ideally it acts and more spcae/volume taken up then expceted bc turning into liq (Temp reduced to condesation poit, and at extremly LOW temps gases occupy MORE space then expected THINK volume follows temp bc of intermolec forces so ig high then high if low then low
spontaneity of dissolution
doest depend on just the enthalpy (thermic), but the entropy makes a huge difference (Remeber not posisble for exothermic to be non-spont but possible for endo to spont) -upon dissolution entropy always increases at some rate so the temp that its at must be more then ∆H/∆S to be spont, if not met then non spont -Ex: when NaCl and H20 mixed, the +∆H broken>-∆H formed leads to small +∆Hrxn(endothermic), and then the +∆S na-cl (break lattice)>-∆S water(solvation layer) so ∆Srxn is +∆S -When inputting it in ∆G=∆H-T∆S then ∆G negative and spont so (endothermic and spont)
Solutions
homogeneous mixtures of two or more substances that combne to be a single phase (usually solids with liq to be liq but can be gas and liq etc but those are called mixtures) -all solutions are mixtures but not all mixtures (gas +liq) are solutions (two or more susbtance in one phase) -solute: what gets dissolved, they move freely and interact with the intermolc forces of solvnet (dipole dipole etc), and usually gets broken down, when dissolved they can then freely interact with other dissolved chemicals -solvent: the solution that the solute gets dissolved in and remains the same phase before and after, usually in greater quantitity
Coordination and Acid/Basesq
inroder for soomething to coordinate something else it must be the oppsite bc of attraction, so an atgom that coordinates +cations means that it must be negative and also a lewis base (e- donor) to be able to coordinate the amt of + charges together. On the other hand the same princples applies but in reverse to a coordiante bond with neg chages the middle guy has to be postive and electron accepting (lewis acid)
Vapor Pressure formula
mol fraction not moloc weight
bicarbonate buffer system
most important buffer system that keeps blood pH from changing drastically Note: the reverse arrow is larger (more thermo favorable) Ex of WA and CB buffer system going back and forth
rate law equation (expression)
must be determined exp for a rxn at certain temp -overall tells you what the rate limiting step is and which elements used to determine rate limitng
pH and pOH
p tells you to -log(x) -when -log10(1e-7)=x you basically saying -(-7log10(10)) (and log10(10)=1) so -(-7)=7, basically when ever have 10^-x then pH will be +x -together though bc of autoionzation of water, ph and pOH must equal 14 -pH+pOH=14 -p(h)=-log[H+] -Physio blood Ph is slightly basic at ~7.5 -remebr lower pH more acidic, higher pH more basic -lower pOH more basic, higher pOH more acidic -remeber pH 7 Is only neutral when at 25C (any change in temp changes temp) - when -log(10^-2) =2 BUT +log(12^-2) is -2 (only opp of exponet when -log -ph+poh=14 comes from log(xy)=logx+logy
Weak Acids and Bases
partially discoc into its Conjugate -bc partially dissoc. then in equilibrium, and bc of that will constantly go back and and forth btw WA and CB -bc at equi will switch btw forms and bc of that Ka is relatively low (less then 1) and Ka (WA) and its CB's Kb will be relatively similar/close to each other (bc together has to go btw both forms but still must equal Kw) -Lower Ka, weaker acid same for Kb, bc less it dissociates (more favored toward reactants) -Stronger WA then weaker CB (although both weak) -bc at equi its conjugate form is less stable than SA conjugate so likely to react nonstop -WB on MCAT usually amines (NH3) -Ka*Kb(conjugate)=Kw -usually org cmpds
State functions
properties that are determined by the state of the system, regardless of how that condition was achieved -can apply Hess Law to them (product-react) Ex: Density, temp,volume,enthalpy, entropy, gibbs, internal E
Collision Theory of Chemical Kinetics
says molecules must collide to react but not all collisions lead to a rxn, the collisions have to be in the correct orientation and KE>= Ea (sufficent E to overcome Ea) in order to be able to break old bonds and create new Arrhenius Eq: continues on with collision theory -the frequency factor is basically how often do molcues collide, so bc in eq, the more often they collide the faster the rxn, frequency factor also depends on [] so more [] the more frequency -the negative exponent means that as it decreases it becomes less negative and closer to 0 (gets bigger), bc Ea on top the smaller the better (less E needed to overcome) and the greater the temp (bigger denominator so smaller exponent) the faster -Overall: more frequently collide, smaller Ea, increase concetration, and increase temps causes faster rxn rate ****Applys to 2 molec collide, anymore than 2 then freq factor of the right two actually colliding is very very low*****
Solubility
solubility is the max amount of substance till reach saturation, molar solubiltiy change but not Ksp -above saturation a percipitate will form -at sutration, then at equi and dissolve solute at equi with undisssolved, the [] at this state is moalr solubility -below [] of molar solubility is diluted -if -∆G then spont, and solute is soluable -if +∆G then nonspont, and solute is insoluble Most molar solubilites are above .1M and are soluble, those that >.1M are called sparinbgly soluble salts -ionic cmpds gernerally are less soluble in water
Gibbs free E equation
the MAX amount of E released at constant temp and pressure (not looking at ∆T but ∆S) based on ∆S and ∆H -at equi, ∆G=0 -can also apply Hess law: ∆Gproduct-∆React=∆Grxn
standard heat of formation
the change in enthalpy that accompanies the formation of one mole of a compound from its elements with all substances in their standard states at 25 degrees celsius (298K) -be sure to use stoich amt when calc Heat for formation of prdocuts and reactants -Flip equation as needed just be sure to switch the sign of ∆H
Molality
the concentration of a solution expressed in moles of solute per kilogram of solvent -For dilute aq solutoins at 25C the molality and molarity are equal b water density is 1kg/L -used ONLY for boiling pt elevation and freeing pont depression
Partial Pressure
the contribution each gas in a mixture of gases makes to the total pressure -basically, Partial Pressure of A is the mols of A/total moles*total Pressure aka, element mole composition*total P, uses mol fraction then multiply by total P
Solvation/Dissolution
the electrostatic interaction btw solute and solvent where it breaks the intermolc forces of the solvent-solvent and solute-solute to become solvent-solute -when water is the solvent called hydration -when new interations stronger-> exothermic -when OLD interactn stonger->endothrmic (took a lot of E to break), most common in dissolutions (old>new) bc heat must be supplied to break High E bond -when old and new interactions are the same strength then ∆H=0 (old=new), in which the enthalpy change is 0 and are called ideal solutions
bond dissociation energy
the energy required to break the bond between two covalently bonded atoms -apply same rules as before in Hess law -bonds broken -formed, use this bc bonds broken ∆H should be higher bc its endergonic to do so -basically also tells u ∆Hrxn
heat of combustion
the heat of reaction for the complete burning of one mole of a substance -When thinking of stabiltiy and heat of combustion, think when combustyed(turned into its elemtns +Co2 and H20) the more heat released the more unstable it was bc had a higher E to begin with and high E is not stable, but lower heat means more stable bc lower E to begin with
Charles Law
the law that states that for a fixed amount of gas at a constant pressure, the volume of the gas increases as the temperature of the gas increases and the volume of the gas decreases as the temperature of the gas decreases THINK CTA Charles inilved in temp (only value with temp involed)
common ion effect
the lowering of the solubility of an ionic compound as a result of the addition of a common ion, this is basically cahnges in molar solubility bc of diff env condtions -can be with the same cmpd or diff chemical with same ion (Ex: XCl and YCl) -when adding an ion to the solvent and that same ion already in solution then the molar solubility ,[] at satuarion, decreases but the Ksp remains the same bc the other ion molar solubility increases to keep it constant but the common ion solid will form -think of this like Ice tables, and remebr products change by +X and reactants change by -x -it supress the ionization of a weak acid by addinf more ion to a producit of tis equi
Vapor Pressure
the pressure exerted by the evaprated particles about a liq onto the liq (to keep them from turning into gas to keep at equillibirum) [A]=Kh * Pa SO [A1]/P1=[A2]/P2=Kh -bc of this can think of pressures as measures of [] and directly realted and this used in gas exchange -if atm P changes the partial pressure of O2 in atm changes and the gas exchanged amount is also changed -if partial Pressure of a gas is increased then the amount of that gasin the blood also increases
osmotic pressure
the pressure for water to move bc of solute [] -high solute [] low water then water wants to move and omotic Pressure high -low solute [] and high water then water wants to stay and osmotic P low -osmotic P is sucking P of water
Gay-Lussac's Law
the pressure of a gas is directly proportional to the Kelvin temperature if the volume is constant
Aq solutions
the solvant is water -when putting acids in aq solutions it leads to hydronium (H30+, think as um as + bc ammonium Nh4+), in which the H+ from a solute is given to H20 -H+ is never found alone but found bounded to e- pair donor (carrier) like water and this H+ being carried is ex of coordinate covalnet
reaction mechanism
the step-by-step sequence of reactions by which the overall chemical change occurs -each step shows how what molec collide and rxn with which -the slowest step is the rate limitng step -the intermediate/product of the steps (except the last which is our final product) are consumed almost immediatly right after they are made
freezing point depression
to answer given here is lowered of the original temp so be sure to note ∆T or new freezing pt (Old-this value) -with new solutes added that interferes with forming lattice as solid state so more E must be removed from the solution to soldify -can use K or C
Ideal gas law
use only for IDEAL gases -Ideal gas: No intermolec Forces and occupy no volume /neglible space (the molec themselevs occupy no volume comapred to volume occupied by gas this means that ideal gases are infently comrpessible bc dont have to worry about the volume of molec but real gases are not ifnfeintly comrpessible they are incompressible )- NO INTERMOLEC FORCES BUT COMRPESSIBLE -R can be 8.21e-2 L*atm/mol*K or can be 8.314 J/K*mol (comes from Pa/Pascals) -the R value will be given just be sure to use the write one and make sure all units match -it is used to find P, volume, Temp, gas denisty (mass(g)/volume(L)) and molar mass (from moles) -One mol of ideal gas occuipes 22.4L at STP
Kinetic Molecular Theory
used for gases -gases have neglible volume, have no intermolc F, they have continous random motion, collisions are elastic meaning there is no conservation of momentum and KE energy, the avg KE is proportional to temps (think as little rubber balls bkuncing off eachother) -Overall: speed of particles realte to aboslute tmep (although actually hard to define) and larger they are the slower they move (so heavier gasses diffuse more slowly bc of its smaller avg speed)
Alveolar Capillary gas exchange
utilizes A1/P1=A2/P2 -the A is the [], and the P is a measure of its solubility, also note that is for the same gas -If [A] is high then your partial P (amount dissolved) at the same time is smaller(doesnt move), but when compared to the new one (A2) as your [] A2 is higher then that of A1 then your partial P2 will be lower bc it will be dissolved??? **double check this rationale***
Transition State Theory
when mollecules collide at equal or greater E to Ea then a transition state forms -in transition state, the old bonds are weakned and new bonds BEGIN to form -at this point the transtion state/activated complex has the greatest E than both products and reactants -min E needed to get to this state is the Ea -once this is formed/Ea is met, no more additonal E is needed to let the rxn go forward, basically just need to meet Ea any E above Ea wil make same rxn and nothing else will change bc just need to meet min
Hess's law
when reactants are converted to products, the change in enthalpy is the same whether the reaction takes place in one step or in a series of steps -be sure to use stoich amt when calc Heat for formation of prdocuts and reactants -Basically, break down rxn to its components and applying stoich -Flip equation as needed just be sure to switch the sign of ∆H Bonds broken - bonds formed when given the indivuals delta H per molec Use prodct-react when given just the delta h formatuiobn When using delta H formation u dont flip the signs bc the - - flips it for u, u can add everything but thats when u need to flip signs based on where its at
dynamic equilibrium
when the RATES of the forward and reverse reaction are happening at the same rate (doesnt mean [] of reactants and products are equal but just means the rate of forward and revesrse are equal) -Only applies to a reversible rxn, if an irriversible rxn then all products will go to completion and once that happens that at static equi (Not dynamic) (irrevesrible means commited and often rate limiting) -reversible rxn means products never go to completion bc by the time product is formed it will react together to turn back into reactant -rate of forward=rate of reverse -in terms of entropy, rxn will reach equi when the system's entropy (E distribution in system) is at its max (and can no longer spont change to diff state and any firther change will reduce entropy and icnrease ∆G) and Gibbs Free E is at its min (close to negative or negative as possible)??-right info just check explain---
autoionization of water
when water rxn with itself produces an H+ (H30+) and OH- and at equilibrium with Kw at 1e-14 @ 25C (298K) -basically says no matter what you rxn with water, the total [H+] and [OH+] will be equal to 1e-14 (one can be higher and one lower but together add up to that -At equilibrium, the [] are equal at 1e-7 each (neutral) -This happens bc of Kw and equi, when adding H+ or OH- (product) it shifts equi to left, add whatever you added will be at a higher [] and the other will be at lower (together though equals Kw) -Note: Kw is based at 25C/298K, only way to increase KW (lower the exponent to Kw=1e-11 etc), is to increase temp, so change in [], P, Volume won't affect Kw
Le Chatelier's Principle
∆ in [ ] -equi will shift toward the direction in which [] ↓ -equi will shift AWAY from the direction in which the []↑ Pressure or Volume ∆: for gases only -P↑ & V↓: shift to side with least moles -P↓ & V↑: shift to side with most moles -Think of volume and room then apply to moles, increase Volume means more moles and bc V and P are inverse that means P decreased ∆ in Temp: think of exo and endo as product and reactants of heat respectivly then think as temp change as change in [] wherever the heat lies on the equation (like if product then product [] increase etc) -Exothermic: ↑Temp then shift to left, Temp ↓ then shift to right -Endothermic: ↑ Temp then shift to right, ↓ shift to the left (temp removed etc)
Le Chatelier Principle Explained:
∆ in [] -equi will shift to the forward when there is less products bc the reactants are high (away from increase) to increase Q to Keq, -equi will shift to the reverse if reactants removed bc that causes increase in Q and so Q needs to get smaller to Keq Pressure or Volume ∆: for gases only -P↑ & V↓: shift to side with least moles -P↓ & V↑: shift to side with most moles This is bc PV=nRT, and you want to restore orginal P, if increased P then moles also increased and system reacts to this and wants to lower P by consuming the bigger moles and work toward the direction of the smaller (big and wants to become small so equi shift that way), number of moles determined by stoich coefficient, can also just think that moles wants more room so if P increase shift to smaller moles if P decreases then shift to higher moles to restore balance Temp ∆: Keq is shifted not Q, so Keq must change to meet Q again -think of endergonic rxns as heat as reactant -think of exergonic rxns as heat as product -then think that temp is a function of heat -if increase temp in endothermic rxn then temp increased in reactant and equi shifts to right (away from heat), if temp lowered then shift to the left toward the heat
∆G and ln
∆Gº- Bottom formula -ln(>1) -> ln value is (-) and rxn in NON-SPONT -Ln (<1) -> ln value is (+) and rxn in SPONT ∆G (NOT STAND)-middle formula when comapred to nEF -ln(>1)-> ln value is (-) BUT SPONT -ln (<1)-> ln value is (+) BUT NON SPON Keq=1, then at EQUI
