User:Xenomancer/LLE Titration Evaluation/KHP Soln Prep

Preparation of KHP standard solution

Chemicals

 * 1) ~22 g potassium hydrogen phthalate (KHP), ACS or USP grade
 * 2) ~1200 mL distilled water (DI)

Labware

 * 1) 1&times; metal spatula
 * 2) 1&times; 100 mL glass beaker
 * 3) 1&times; 500 mL glass beaker
 * 4) 1&times; glass stiring rod
 * 5) 1&times; medium glass liquid transfer funnel
 * 6) 1&times; 1000 mL glass volumetric flask w/ stopper, grade A
 * 7) 1&times; 1 L amber glass bottle
 * 8) 1&times; blank label (for glass bottle)
 * 9) 1&times; permanent marker (for label)

Instrumentation

 * 1) 1&times; analytical mass scale
 * capacity &ge; 25 g
 * uncertainty ($$\,\sigma_{scale}$$) &le; &plusmn;0.5 mg

Procedure

 * 1) Weigh out a sample of KHP into the 00 mL glass beaker.
 * 2) Place the 100 mL glass beaker on the analytical scale.
 * 3) Zero the analytical scale to neglect the tare weight of the 100 mL beaker.
 * 4) Remove the 100 mL glass beaker from the analytical scale.
 * 5) Using the metal spatula, transfer roughly 20 grams of KHP to the 100 mL glass beaker.
 * 6) Place the 100 mL glass beaker back on the analytical scale.
 * 7) Wait for the analytical scale to settle on a fixed reading.
 * 8) Record the exact mass of KHP $$\left(\,m_{KHP}\right)$$.
 * 9) Quantitatively transfer the weighed out KHP from the 100 mL glass beaker to the 1000 mL volumetric flask using DI.
 * 10) Using the medium glass luid transfer funnel
 * 11) Bring the volumetric flask to volume with DI.
 * 12) Seal the volumetric flask with its stopper and mix well.
 * 13) Mixing is satisfactorily completed 3 minutes beyond complete dissolution of the KHP.
 * 14) Be sure to invert the volumetric flask several times while shaking to agitate the neck volume of the flask.
 * 15) Transfer the solution from the 1000 mL volumetric flask to the 1 L amber glass bottle.
 * 16) Remove the stopper form the volumetric flask.
 * 17) Ensure that the 1 L amber glass bottle is clean.
 * 18) If the amber glass bottle is visibly dirty, rinse it with DI.
 * 19) Transfer a small aliquot (10 mL to 20 mL) of solution from the volumetric flask to the amber glass bottle.
 * 20) Close the amber glass bottle and swirl the solution around, covering all surfaces, to rinse the container.
 * 21) Open the amber glass bottle and empty the contents into the appropriate waste container.
 * 22) Repeat the last three steps two more times.
 * 23) Carefully transfer the solution to the amber glass bottle.
 * 24) Label the bottle with the appropriate information.
 * 25) Solution name: "$$\left( \text{num}\pm\text{err} \right)\text{M}$$ KHP Standard"
 * 26) Date prepared: "MM/DD/YYYY"
 * 27) Name of preparer: "FirstInitial LastName"

Data analysis
The concentration of KHP in the standard can be found via straight forward dimensional analysis.

Error analysis
Using the standard differential error formula

or

and the measurement/instrument uncertainties

$$\,\sigma_{V_{flask}}=0.20mL\rightarrow\Delta V_{flask}=\pm 1.960\times 0.20mL\rightarrow\Delta V_{flask}=\pm 0.392mL$$

$$\,\Delta m_{KHP}=\pm 0.0001g$$

the concentration uncertainty for KHP is given by

where

and

Substituting for the partial derivatives yields

The simplified form for the uncertainty using the example data is

which means the concentration is fully given by the equation

or