Test 1: Definitions Flashcard

Accuracy
agreement between measured and true or accepted values
Precision
reproducibility between replicate measurements
Determinate Error
Error that can be avoided or corrected
Indeterminate Error
Truly random error; inherent uncertainty in measurements.
weight
attraction of earth
mass
for required for acceleration
Molarity
1 mole in 1 liter solution
density
specific gravity, grams/mL
Formality
contains 1 formula weight in 1 liter solution
wt%
weight/wt of vol*100
vol%
Vol/Vtot*100
wt-vol %
wt/vol soln *100
milligram %
mg/100mL
Equivalent
amount needed to react with 1 mole of reactant
Normality
1 Eq/liter
Sig figs
# of digits required to express a result consistent with given or measured precision
Exp prop error
sy/y=z(sa/a)
mult ratio by exponent, mult by answer
Log prop error
sy=.434(sa/a)
antilog prop error
sy/y=sa/.434
divide by .434 the mult by answer
confidence interval of the mean
a range with a certainty of containing the true value

u=x+-tSx=x+-ts/sqrt(n)

F-test
comp 2 data sets
Fcalc=s2^2/s1^2
Fcalc>1 big always on top
t-test
|x1-x2|/sqrt(Sx1+Sx2)=tcalc
Qtest
toss out data
|x-xnear|/|xhi-xlo|=Q
average deviation
|sumation xi-x|/n
relative deviation
%
ppt
relative to mean for specific point
|xi-x|/x
relative average deviation
%
ppt
avg dev/x*100
Relative std dev
%
ppt
s/x*100
coeff of variation
same as rel std dev in %
s/x*100
Std error of mean
Sx=s/sqrtn

always < s

avg error
error referenced to true value
summ xi-xtrue/n
rel error
%
ppt
xi-xtrue/n
rel avg error
%
ppt
avg error rel to true val
avg err/xtrue*100
Le chatelier
effects for concentration pressure and temperature change in equillibrium
charge balance
total charge of soln must be neutral. include H and OH
Mass Balance
For particular type of species, the sum of the added amounts must be equal to the sum of all the possible forms in solution
complexation
solubility begins to increase after a certain concentration due to formation of complexes.
Activity
A=y[C]
concentrations are really the Activity
decrease effective charge (effect on A)
decrease
DHLL
log y=-.5085zi^2sqrt(u)
Ionic strength
u=1/2(summCizi^2)
Ion strength effects
# ions increase
strength increase
EDH
DHLL/1+(a*sqrt(u)/305)
a is effective hydrated ion radius
a=900 for H
colloidal
tyndall efect – light scattering
small particles<100nm
Crystalline
inch diameters
desirable for analysis
precipitate mech
Nucleation followed by particle growth
in a super saturated solution
nucleation
small aggregates form
particle growth
additional molecules deposit on growth nucleus
supersaturation
sol’n contains more solute than would be present at EQ =>precipitate
ss and qss
Q-S

Q-S/S

precipitate rate
depends on SS
rate-k(Q-S)^x
k and x constants
particle growth rate
depends on ss and nucleus surface area
rate=k’A(Q-S)
rate chart
part
rate| / )
| / )
|/–/nuc
———
RSS
coprecipitation
when a normally soluble substance precipitates out due to adsorption or occlusion
postprecipitation
contamination by other insolubles

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