MEW =
Equivalent
Weight
1000
Determine the volume of liquid needed, using the following equation:
V1 =
(V2)(N)(MEW)
(DFP) (SPGR)
Where:
V1 = Volume of solute needed.
V2 = Volume of solution to be prepared, in ml.
N = Desired normality of solution to be prepared, in ml.
MEW = Milli-equivalent weight of the solution.
DFP = Decimal fractional purity of solute.
SPGR = Specific gravity of solute.
PART C - REVIEW STANDARDIZATION PROCEDURES ENSURING THAT
CHEMICAL SOLUTIONS ARE STANDARDIZED AT THE REQUIRED
INTERVALS
As a senior petroleum laboratory technician, you must evaluate solutions to ensure that they have been
standardized at the required interval. Standardization procedures include:
Set up the titration apparatus.
Verify that the burettes are clean and serviceable, to include tips and proper fitting stopcocks.
Rinse burettes several times in solution to be titrated.
Change burettes with solution; zero burettes before titration.
Titrate the primary standard in the Erlenmeyer flask with the solution in the burette.
Swirl the flask during titration to ensure homogeneous mixing. Wash down the insides of the flask to
ensure no titration solution is clinging to the sides of the flask.
Titrate slowly as the end point approaches.
Record the volume of solution used to reach the end point.
Repeat the titration procedure at least two additional times.
Calculate normality to four decimal places. Perform calculation for each titration using the following
equation:
N=
(W)(DFP)
(MEW) (V)
Where
N = Normality of solution.
W = Weight of primary standard use in grams.
DFP = Decimal fractional purity of primary standard.
MEW = Milli-equivalent weight of primary standard.
V = Volume of solution used, ml.
Obtain the average value of normality titrated.
Label the standardization solution for identification. Include the date standardized, the type of solution, the
normality, and the rank and name of the person who standardized it.
2-3
QM 5181
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