Last Second Things Forgotten Flashcards

Question

Approximations for weak acid

Answer 1

Moles at equilborum of Ha would be Ha - H+ disscoates as one to one - however weak acid, unlikely much , hence approximated to just Ha Conc of H+ what be = to conc of Ha-, however h+ from disscoation if aqeuous wated. - however if take this to be very small, negkible, hence h+ = A-, and thus H+ When break down? - if Ka string enough then disscoation of h+ from acid noticeable hence first approximation breaks down - if bery dilute or high TEMP, then Kw of water increases hence pH too, so this breaks down

Answer 2

Increases with temp, is used to control all concs of Oh- and H+ at a certain temp Remember Monobasic etc based too for strong alklai

Answer 3

Add acid, reacts with A-, producing more Ha thus equilborum shifts to left Add alklai, reacts with h+ m reducing h+, so Ha dissocsted to increase, and shift to the right ph human blood is 7.4, must be kept between 7.35 and 7.45, else enzymes denature

Answer 4

1) add some acid to a conical flask 2) usinf a pH probe, add the electrode to the flask 3) connect to a datalogger so it autmaotically measures 4) add thr base to the burette and SWIRL 1cm at a time 5) or use MAGENTIC swirled and add slowly 6) when approach the rapid pH change add very slowly Then can plot graph

Answer 5

Equivalence when one volume matches other reaction fully, also middle of line End point assumed to be same as equivalnce but when conc of Ha in indicator = A-, where the colour of the EQUILBKRUM lies in thr middle at that point Indicators are just buffers really with different colours, and change of h+ or alklai causes it to be different colours, such that it goes through all as you go The indicator chosen must fall in the range of the vertical section of graph At end point as ha = a- PKa = ph again, 2) curves Remember weak acid curve starts high and is curved due to acting like a buffer, finishes whatever, but because starts high the long part of graoh is high . Remember that 3 units vertical, and ,ost of it above pH 7 There is no indicator suitbsle for weak acid weak base at a L

Answer 6

Is the enthlapy change that accompanies the formation of one mole of ionic compound from gaseous ions

Answer 7

1) enthalpy change that accompanies one mol of SOLUTE dissolving in AQEOUS soltuion 2. Hydration is the ENTHALOY that accampiex one mole of GASOEUS ion dissolving in aqueous soltuon IN WATER SOLUTION SEEMS to be the difference between energy released when forming bonds with water, against energy needed to dissociate lattice right, so if energy r,eased is more and soltuion negative dissolve? No, even with positve soltuion, due to entripy it could still be feasible Base case ions GASOEUS at the top, note the soltuion could be positve or negative

Answer 8

Ionisc size increases, attraction ti water / ionic attraction decreases, so less energy released less Exothermic. Same with chwrge If ENTHALOY chaneg less Exothermic lower melting point too , or greater However other factors like bonding make a difference too

Answer 9

Only takes into account energies , not kinetics, such as ror , activation energy, such that just because feasible , might take 1000s years to complete

Answer 10

Colourless to permanet pink self indicating at end poitn For iodine thisukfste what happens is a chemical in acidic environment is added to KI, where ioidne ions fully react to produce a SET AMOUNT OF IODINE, making it orange yellow. When thsoldukfste in burette rescts, makes iodine iodine ions, so colourless Hence colour fades When approaches pale straw at starch tk accentuate the colour. Final change sk blue black to colourless We add at the end because complex so string that reduces amount of iodine Use balancing numbers ti find origami Iodine ions to idoine , then whatever that is transfer to iodine in first equation and stoichmetry again Remember go from left bala ne, then take to right and balance , scale etc

Answer 11

Most positve is positve electrode negative negative, Most reductucing sn gent mkstcnnegativneetc As metfsks lose electrons they become oizidised, so most reactive is negative agsin Standard is measured against hydrogen h+ system at standard conditions , remember must be 1 mol and if it’s non metal then SAME conc not necasially 1 mol Salt bridge allows ions to flow E cell is positve - negstvif

Answer 12

1) conc not the same - then based on the EQUILIBIRUM more or less electrons produced, hence more then the half cell ptoentisl becomes more mega y or / positve accordingly 2) DOESMT TAKE INTO ACCOUNT KINETICS AGAIN, no ror, ea 3) other condtions not standard will chnage the potentials meaning using these to predict womt be fully accurate

Answer 13

Primary class non RECHARGABLE used once, two half cells, Secondary cells RECHARGABLE, chemical process can be reversed to produce energy Remember good for small, lithium blew up before Fuel cells use energy made from fuel and oxygen to CREATE A VOLTAGE - fuel and oxygen enter, produced leave - electrolyte stays in the middle - as long as continously powered keep going etc # use fuel cell that doesn’t produce any emissions like hydrogen

Answer 14

Have h+ in both and oh. In both equations but give the same e cell

Answer 15

Remember sqaure planar only formed with platinum gold palladium else all tetrahedral - cis platin used ti treat tumours by binding ti dna , causing apoptosis, however side effect is kidney damage, but is used Cos trans can be shown by tetrahedral octahedral together oppsitr But optical only by octahedral and must be 2 alone The cis is optical and trans therefore 3 isomers Cis trans shown in SQAURE PLANAR ROO!, where cis platin is two ammonia two chlorine - remember these remove chadg

Answer 16

In ammonia, cu Oh dissolves to form copper 4 ammonia 2 water AND cr( Oh)3 dissolves to form cr (Nh3)6 (purple) In excess Oh Cr(oh)3 dissolves to form cr (oh)6 dark green Colours forgot Mn2+ pale pink to mn(oH2) light brown Cr3+ is village becomes grey green then dark green Cr (6 H2O) village ti purple Remembe reactions with ammonia give the same, just represent with oh , etc

Answer 17

Fe2+ central metal ion, form dative binds with fe2+ oxygen, when needed ligand sun with co2 However co forms strongest dative bonds, which irrevsieble so useles hamelglonin and thus toxic

Answer 18

Cr2+ is blue, cr3+ is green 6+ / cr2o72- is orange obv White cuI , brown I2, brown cu, fe 3+ to fe 2+ orange brown to green Remember ti become fe 3+ need to become oxidised so someth else reduced Cuso4 is blue, cu I’d brown, copper csn cisproptinate herr

Answer 19

E,ectiphikic additon is hbr to alkene , susbtition is nitration / brominstion / acylation etc of benzene / ohenol Nuelcophilc substiopj is like Oh- with halolaken Addition is H- or CN- with nabh4 H2O NACN h2so4 accordingly to alchol ketone reduction

Answer 20

Remember 2 o for reflux, one otherwise and ketone, one h2o released each time 2 h reduction, else hcn

Answer 21

Esterificsrion = cabroxykic acid alchol, acyl chloride alchol. Acid anhydride alchol ( and produces a cabroylic by itself), also like in amino acids whatever, sukfruic acid catalyst and reflux forms ester bond Amides formed when acyl chlroide react with ammonia , and primary amines ti form secondary amides Acid and base hydrolysis, acid hydrolysis returns the cabeknsylic acid fully and the alchol , but if amide then protonated ALAKLI hydrolysis returns the carboxylate salt and alchol this time Aycl chlroide reactive enough ti form esters with phenols, alchols, water cabroylic, whole point of being a derritiave is that if hydrolysed you form larent chain, thr ammonia and amine the amides How to name amides? Longest chain but an amide, everything else N substituted in ALOHABETICAL ORDER ( can only be max 2 anyways) Acid anhydrides less reactive so used instead of acyl chlrides, can form all phenol alchol amine ammnoia to make amides too

Answer 22

If primary then burly amine, if last postiom Else if Randi postion, 2 amino If secondary teriwty then same as amide , main chain amine , N substituted

Answer 23

Act as bases as they have lone pair that can donate to a h+ to form a dative covalent bond, accept a proton hence a base - react with acids fully absorb acid , become protonated Halolakne + ethanol + excess ammonia then NaOH ( where excess ammonia presents sub again, ethnaol prevents hydrolysis of halolakne). Secondary means use primary amine instead of ammonia etc Nitro benznen + 6 H and tin conc hcl and NaOH becomes phenyl amine , get rid of two o so 2h2o

Answer 24

Amin and carbox group - with acids protonated and soaked up - with base, forms salt With ESTER BECOMES PROOATED due to acidic conditions

Answer 25

Normal monomer means n-1 H2O formed 2 monomers is 2n-1 H2O formed 2 monomers when dill dicabrox, amino acids etc is only one Acid hydrolysis of an amide protonated amine part, returns cabrox Base hydrolysis returns amine, salt with acid , gives n back

Answer 26

Formation = CN with ketones alchols hydroxyl nitriles Or CN KCN and ethanol with halolakne gives Now reduction of nitriles , 2h2 and ni caltyst 423k , forms AMINE Hydrolysis, 2h2o + hcl forms cabroylic aicd and ammonium chloride Other csbrin extenders are acylstiom , alkylation Acylstiom makes a KETONE BTW with double o on first cabron

Answer 27

Büchner, remember to filter paper, let it reduce etc Melting point, looking for sharp melting range, do trial, then low heat and accurately Det sin rnahe, more sharp the better more prue against a book Solids impure lower melting but when boilign higher

Answer 28

Stationary phase silica mobile solvent, Gas = inert gas mobile, liquid adsorbed on inert solid The degree of interaction between mobile vs stationary determines how far / how long it stays in chromatrgom, where retention times are used to compare - pwak area represents concentration, so I’d run test with known concs can make a calibration curve to also determine its concentration Remembe fecl3 to ohenol makes purple, else low ph as test

Answer 29

Run against nucleons and spin prop try which is apparent when odd Hence done on carbon nmr and proton nmr, csbrkn13 isoptope @% present in all compounds, so useful Deuterium even, so doesn’t show up, hence D2O etc is used for proton exchange to identity cabroxykic or nH groups , as they won’t appear. Cdlcl3 deuetared shows in cabron but filtered, good solvent, TMS has one group esch so used a st standard small peak on Number of peaks represent number of environments Remember splitting from non equivalent only, n+1 9 refers to certain types