This analytical technique includes:
 Empirical formula and Molecular formula
 Gas equations Eg. Pv=nrt
 Percentage of water/ measuring water content
 Limiting and Excess reactant equations
 Precipitation reactions
Key steps in a
precipitation reactionwhat this looks like
Weighing the sample
Forming a precipitate
Filtering the solution
Weighing the dry precipitate
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#1: Accurately weigh the
mixture to be analysed.
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#2: Dissolve the mixture in a
suitable solvent; filter off and
discard any insoluble material.

#3: Add an excess amount of
solution, that will form a
precipitate with the substance
being analysed.
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#5: Dry the precipitate and,
cool and accurately weigh.
Repeat until a constant mass is
achieved.
#4: Filter off the precipitate
and wash it with a small
quantity of substance.
http://www.youtube.com/watch?v=g6nXg
zjW7nw&feature=related
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Gravimetric analysis is a technique through which the
amount of an analyte (the ion being analyzed) can be
determined through the measurement of mass.
Gravimetric analysis depend on comparing the masses of
two compounds containing the analyte.
Advantages
• Precise measurement/
high degree of accuracy
(6-figure)
• Helps in determination of
atomic mass, of elements
• Doesn’t require a series of
standards to calibrate the
unknown solution
concentration
• Helps in calibration of
other instruments
Disadvantages
• Limited group of
elemental analysis
• Convoluted methods
• Only suitable for high
concentrations
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Gravimetric analytical data is interpreted from the
weighing of the precipitate at the end of the experiment.
To do this, you must weigh the instrument in which the
precipitate will be weighed in, note the weight, and then
weigh the precipitate. The solid weight is determined by
the difference between the two.

Calibration is predominantly undertaken by gravimetric
analysis and is the method most commonly used by
laboratories accredited to ISO17025. There are colorimetric
methods in use and these are often used for checking pipettes
and for non-accredited calibration. Gravimetric analysis is
preferred due to the simplicity and the traceability to an
absolute standard. Gravimetric methods are also often
recognsied as a more economical way of calibration.

Gravimetric analysis for pipette calibration entails dispensing
samples of distilled water into a receiving vessel in a
precision analytical balance. The density of water is a known
constant, the temperature, barometric pressure and humidity
are recorded (the Z-factor used in the final mass calculation)
and kept within certain limits and thus the mass of the
dispensed sample provides an accurate indication of the
volume dispensed.
Determining water content of
complex materials. Eg. Food
and soil
Treating ore (part
of earth’s layer)
Purity evaluation
Determination of atomic
mass of elements
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Geomarine survey systems
A chunk of ore is treated with concentrated nitric acid and
potassium chlorate to convert all of the sulfur to sulfate.
The nitrate and chlorate are removed by treating the
solution with concentrated HCl. The sulfate is precipitated
with Barium and weighed as BaSo4.
Monitoring the air
Concentrated HCl to
remove nitrate and
chlorate
Sulfate with
nitrate and
chlorate
BaSO4
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Gravimetric analysis obtains more accurate data about the
composition of a sample than volumetric analysis does,
however it takes longer to perform in the laboratory.
Gravimetric analysis is analysis by weight, where as
volumetric analysis is by volume.
Gravimetric analysis is less sensitive to temperature than
Temp.
volumetric analysis is.
Volumetric- volume
Gravimetric-weight
Gravimetricless sensitive
volumetric
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Looks like a titration/ same as
Measure from bottom of meniscus
Wherever there is a concentration of a known solution, to
be found, then volumetric analysis is the method to use.
Quantative analytical technique
Measure from bottom
of meniscus
Titration/
volumetric
analysis

Read the meniscus again. Subtract the
first reading to find the volume
added.

Repeat the first 5 steps.

Read the burette and perform an
accurate titration by repeating step
7.
Steps

Clean the pipette and rinse it with a
bit of the solution to be used.

Clean a conical flask using distilled
water.

Pipette the specified volume of one
reactant into the flask.

Stop as soon as the end point is
reached.

Rinse down the edges of the flask
with distilled water.


Add the indicator if required.
Subtract the initial reading from the
end point reading to give an accurate
titre.

Clean the burette and rinse with bit
of the second reactant solution. Fill
with the solution. Does not need to
be exactly on zero. Note the reading
on the bottom of the meniscus.

Repeat the accurate titration (steps
9-12) at least twice more. The titres
should be within 0.1cm of each other.

Take an average of your three
accurate titres. Use this as the
‘volume added’ in the calculations.

Perform a preliminary (rough)
titration by running the burette
solution into the flask, making sure to
swirl the mix, until the end point is
reached.
http://www.youtube.com/watch?v=8UiuE
7Xx5l8&feature=fvsr
Equipment

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Advantages
Fast and easy to perform
Only basic laboratory
equipment needed
Very cheap
Accurate results
Different methods
available for different
substances


Disadvantages
Relatively large sample
size needed
Only suitable for relatively
high concentrations

Data is interpreted by using three concordant titres. These
help to give accurate results and need to be within 0.1 of
each other.
Concordant titres- they should
all be a similar colour


To ensure proper measurement of
large volumes in the laboratory,
volumetric apparatus should be
calibrated regularly. Two of the most
common apparatus calibrated are
volumetric flasks and serological
pipettes.
*If the error is more than 0.03% then
the apparatus should be discarded or
changed into a volumetric apparatus

Manual procedure via volumetric flask
-
Weigh the volumetric flask.
-
Fill the volumetric flask with distilled
water, up to the mark
-
Weigh the volume of distilled water
contained in the flask.
-
Calculate the true volume of
glassware via the formula
-
Record the data
-
Do the same procedure with the
serological pipette.
-
Record again your data.
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Used in bio diesel manufacture to ensure that the mix has
a neutral pH.
To determine the amount of acetic acid in manufactured
vinegar.
To determine fatty-acid content and unsaturated-fatty acid
Manufactured
content.
vinegar
Brain imaging and MR imaging, as well as routine clinical
use.
Suitable for direct titrations
Suitable in Determination of iron
brain imaging
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Compared to other analysis’; for example gravimetric
analysis, volumetric analysis is less accurate and less
reliable.
In volumetric analysis, you are more likely to encounter
limits of sensitivity in volume measurements, compared to
other analytical techniques.
A mass is generally easier to determine and standardize
than a concentration.
Errors associated with volume measurements are
minimized in other analytical techniques, such as
gravimetric analysis.
Volumetric analysis less accurate