QCHEM FINAL

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define precision: -measure of the reproducibilty of a result
-can be evaluated by standard deviation
degrees of freedom are used to calculate confidence interval are...: number of data points-1
A government chemist has performed a gravimetric analysis for chloride ion...: +/-.31%
When an analytical chemist uses the word accuracy, what's meant?: how close the mean from a set of data is to the true value of the composition of the sample anaylzed
A student was presented with a sample of vinegar for analysis...which value for Q rejection?: no values may be rejected
Any diluted aqueous solution has a density near 1g/mL...ID which of the following alternative conc expression is correct?: 1 microgram/L
A solution is prepared by dissolving magnesium chloride in water...calc molarity: 2.71M
The ethyl alcohol content of many beers...what percent of ethyl alcohol?: 3.20% ethyl alcohol
Write answers with proper sig figs =12.7290: 12.7
Find abs uncertainty using sig figs =172.010: 172.0(+/-.2)
The density of concentrated reagent HCL...Find correct conc.: -The Molarity(M) of conc reagent HCL is 12.1
-The molality(m) of conc reagent HCL is 16.1
In medcine, blood sugar is a term...find correct statement.: -the normal rnge blood glucose is 3.9-8.4mmol/L
-a high glucose level reading is above 200mg/dL, that converts into as 11.2mmol/L
High level of gastric acid...how many tablets of antacid are needed to neautralize?: 2
Calc abs or relative uncertainty with sig figs: NOT 9.23....
Traces of organic, man-made hexachorohexanes in sea sediments...are conc pg/g: parts per trillion
pick correct statements: the mean conc found by product A is significantly diff from that of conventional procedure
The equation that reps solubility product is...: [Mn+3]^2[S-2]^3=Ksp
the debye-huckel equation...which statement(s) will be correct?: -As the ionic strenght increases, the activity coeff decreases
Which of the combos of ions and molecules may produce a buffer...?: -50mL of .050M HNO3 and 50mL .1M CH3COONa
-50mL .050M NaOH and 100mL .05M CH3COOH
What's the pH of solution containing .03333M Ca(NO3)2: 6.98
If a .100M NaOH...which metal OH will precipitate first?: Cu(OH)2
the equivalence point for a titration is...: the vol associated with actual stoichiometric quantity of titrant required to complete a titration
magnesium carbonate is slightly soluble in water...what's correct mass balance?: [Mg+2]=[CO3-2]+[HCO3-]+[H2CO3]
A solution contains a .100 M Al(NO3)3...what's correct charge balance?: 3[Al+3]+2[Mg+2]+[H+]=[NO3-]+[Cl-]+[OH-]
Find value of K for reaction HOBr=H+OBr: 2.0x10-9
If 3 stages of base hydrolysis constantsfor phosphate...which statement is correct?: for phosphoric acid, (Ka2=6.29x10-8)
standardization curve...an unknown sample of 100mL of solution containing Cr+3....How many mils of chromium were in the orginal sample?: 2000mg Cr
Fond conc of phenol and phenolate ion...: 1.00x10-2M phenol, 1.02x10-6M phenolate ion
a solution contains .100MNa NO3..what's ionic strength?: .700M
Regarding the matrix effect...: standard additions can min the error caused by the matrix effect
ID all conj acid-base pairs: NO2-, HNO2

OH-,H2O
A solution containing sodium sulfate has a pNa of 5.83..what's the sulfate conc?: 7.40x10-7M
how many mils of HNO3 are required to eract with CaCO3: 194.1mL
regarding ionic strength and activity coeff, which is correct?: -activity coeff measures the deviation of behavior of ions from ideality.
-ionic strength measures the total conc of ions in solution.
Calc pH of .100 M solution...: 7.93
A buffer solution was prepared...what's the pH?: 4.84
Using symbol H2M to rep maleic acid, what's pH and m-2 conc?: pH=1.46,[M-2]=4.68x10-7M
Which are true regarding isotonic pt and isoelectric pt?: At the isoelectric point, the avg charge of the polyprotic acid is 0, and the conc of H2A+ is equal to the conc of A-
A solution containg 80mL strong acid is titrated with 40mL strong base, what's pH?: 7.00
A solution containing 50mLof C2H3COOH is titratedwith NaOH, what's pH?: 4.76
In a titration, 25mL of nitic acis, what's pH?: 9.42
a beaker containing 500mL was determined to contain ammonia,...what's change in pH?: The pH of the solution will go down .087pH units.
Sulforous acid has pKa...at what pH is the HSO3- conc equal to SO3-2 conc?: 7.18
Consider the titration of 25mL of HBr and NaOH, what's vol of NaOH needed to reach equivalence pt?: 50mL
EDTA titrations would be most complete?: Cu+2 at pH 10
A student wishes to use eriochrome black-T...to adjust pH, the student should use:: NH3/NH4+ buffer
cathode defined as...: the electrode at which reduction occurs
write balanced net equation for the following cell...: 2MnO4+16H+5Cd----5Cd+2Mn+8H2O
the half cell potential is: .309V
In the titration of 30mL of a .200M solution....what's the pH?: 6.00
Calc E for reaction...: +.736V
A 100m weak acid titrated with weak acid..correct statements are...: -the equivalence pt is reached when 10mL KOH added
-pH=5 when 5mL KOH added
-pH=8.98 when 10mL KOH added
for titration of 10mL of .1M dibasic base, correct statements:: all are correct
For titration of 50mL of .04M Ca+2 with EDTA, correct statements:: -At pH=10, the most potent complexing ligand of EDTA is a hexadentate ligand
-The equivalence pt is reached when 25mL EDTA added
-pCa=5.91 at equivalence pt
In the context of EDTA titratoin, correct statements:: -EDTA form more stable metal complex in basic solution
-Conditional formation constant allows us to look at EDTA complex formation as if the uncomplexed EDTA were in one form
-Auxillary complexing agent permits EDTA titration in alkaline condition w/o the interfernece of metal hydroxyides precipitation
the space shuttle...correct statements:: -NH4CLO4 funcs both as reducing and oxidizing agent
-Al metal powder funs as reducing agent
In the context of electrochem cell, correct statements:: -reduc and oxida half rxns always occu concurrently in an electrochem cell
-the purpose of a salt bridge is to maintain electroneutrality throughout the cell
-Multiplying a half-reaction by any factor does not change the value of its E

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