INTRODUCTION
As a Petroleum Laboratory Specialist, you should observe laboratory technicians to insure they are preparing
chemical solutions, and handling glassware and equipment correctly.
PART A - VERIFY THE PREPARATION OF CHEMICAL SOLUTIONS
As a petroleum laboratory supervisor, you must ensure that chemical solutions are prepared correctly by
considering the following questions:
Has the glassware been cleaned and prepared properly?
Wash the glassware with soap and water; rinse with tap water and then distilled water.
Air-dry in the inverted position, if time permits, or in drying oven.
If chemical cleaning is necessary, soak the glassware in chromic acid for 6 hours; rinse with tap water,
and then distilled water.
Chemicals are inherently dangerous, safety precautions should always be adhered to when chemicals
are being handled.
Was the correct formula used?
Determine the amount of solid solute needed, using the formula W = (V) (N) (MEW) / DEP.
Determine the volume of liquid needed, using the formula W = (1000) (0.01).
Were the selected chemicals weighed properly ?
Was the correct standard selected to standardize an acid or base?
Was the primary standard paired correctly?
Weigh a clean, dry Erlenmeyer flask on the analytical balance.
Add the grams of primary standard calculated weighing a substance using the appropriate balance.
Record the weight to the fourth decimal place.
- Use the analytical balance
- Use the Harvard Trip balance.
Dissolve the primary standard in an unmeasured quantity of distilled water.
Add two or three drops of indicator to the solution.
Indicators are dyes that change the color, depending on the degree of acidity or alkalinity, of a solution.
They also show the concentration of hydrogen ion of a solution, and they can be used in volumetric analysis
to mark the end of titration, the point of completion of a neutralization reaction.
PART B - EVALUATE CHEMICAL SOLUTION FORMULAS USED BY
LABORATORY TECHNICIANS
Determine the amount of solid solute needed, using the following equation:
W=
(V)(N)(MEW)
DFP
Where:
W = Weight of solute needed, in grams.
V = Volume solution to be prepared, in ml.
N = Desired normality of solution to be prepared.
MEW = Milli-equivalent weight of solute, grams/milli-equivalents.
To determine MEW, the EW must first be determined:
EW =
Molecular Weight
Total Positive
Valence
Then:
The MEW will be determined:
2-2
QM 5181
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