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Grain Science and Industry

Basic Laboratory Equations


(1) Calculating number of moles in a
given weight of a single substance
mol = wtmol wt



(2) Calculating weight of a substance
given the number of moles
wt =mol x mol wt


(3) Calculating equivalent weightequiv wt =mole wt n


(4) Calculating number of equivalentsequiv =wtequiv wt=mol xn


(5) Calculating Molarity of a given
Volume of a single substance
M =molVolume=mol x n


(6) Calculating Normality of a given
Volume of a single substance
N =equiv V=wtmol wt x Volume= n x M

 

Equations for Calculating Concentrations Based on Weight


(7) Calculating the percent weight
of a pure analyte in a given
weight of solution
%(w/w) =wt of analytewt of solutionx 100


(8) Calculating the percent weight
of a pure analyte in a given
volume of solution
%(w/v) =wt of analytevolume of solutionx 100


(9) Calculating the weight of a pure
analyte in a megagram sample
ppm(w/w) =wt of analyte wt of solutionx 10 6


(10) Calculating the weight of a pure
analyte in a megaliter sample
ppm(w/v) =wt of analytevolume of solutionx 10 6


(11) Calculating the density
of a substance
ρ =wtvolume


(12) Calculating the specific gravity
of a substance
sp gr =ρsampleρH20= ρsample at 4oC


Calculating the Weight or Volume of a Reagent to Prepare a Given Solution


(13) Calculating the weight of a
a substance needed to create
a pre-assigned molar concentration
wt =mol wt x M x V


(14) Calculating (13), but correcting
for the percentage of reagent purity
wt =mol wt x M x V x100%purity


(15) Calculating (13), but given
the percent weight of the analyte
wt =%(w/v) x solution Volume 100


(16) Calculating (13), but given
the ppm of the analyte
wt =ppm(w/v) x solution Volume 10-6


(17) Calculating volume of reagent, V1,
with concentration, C1, necessary to
add to a volume of diluent, V2 - V1,
to yeild desired concentration, C2
V1 =C2V2C1




Reporting Analysis Results Based On Moisture


(18) Calculating moisture loss due
to being oven dried (OD)
%lossOD =(wet wt - dry wt)x 100


(19) Converting content (%Y) from
OD to as received (AR) basis
%YOD=%YARx 100100 - %lossOD


(20) Converting content (%Y) from
AR to OD basis
%YAR=%YOD (100 - %lossOD ) 100


(21) Converting content (%Y) from
AR to arbitrary moisture (AM) basis
%Y =%YAR (100 - %AM) (100 - %MoistureAR)


(22) Calculating weight of a sample
on an AM basis
sample wt=%dry matterAM%dry matterARx required wt