By substituting the above expression for the second expression,
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we have the following expression:
Normality x milliliters = normality x milliliters
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(reaction 1)
(reaction 2)
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OR
N1 X ml1 = N2 X ml2
These relationships enable further calculations that may lead to
determinations of the weights of substances that react with the
standard solution.
Verify that the proper amount of solute is used at all times.
This not only aid in the accuracy of the process, but also saves
time and ensures safety. As mentioned earlier, you must ensure
that correct calculations were used to determine both the weight
of solids and volume of liquids.
The following is a step-by-step description of the process of
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standardization by titration.
We are assuming that a 0.1N
solution of an acid is to be prepared and standardized.
In
addition, a quantity of 1 liter is required.
1.
Select a basic primary standard for an acidic solution,
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note the milliequivalent weight and the (assay) number (this
information is usually found on the container of the substance.
2.
Calculate the weight of the primary standard required to
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neutralize about 40 milliliters of 0.1N acid with the use of the
following function (where DFP is decimal fractional purity).
Weight needed (Mg) = (N) (40ml) (MEW)
DFP
3.
Weigh a clean and dry Erlemeyer flask on an
analytical
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balance.
4.
Add the grams of primary standard calculated in step 2
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above, and record the weight to the fourth decimal place.
5.
Dissolve the primary standard in an unmeasured quantity of
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water.
6.
Add two or three drops of methyl orange.
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3-5
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