2. What is gravimetry?
Gravimetric analysis is a type of laboratory technique used to
determine the mass or concentration of a substance by measuring
a change in mass. The chemical we are trying to quantify is usually
called the analyte.
Gravimetric analysis can yield results of high accuracy (ideally,
but it is a lengthy procedure that requires a lot of attention, so it is not
advantageous if many samples are to be analyzed.
Isn’t advantageous if many samples are to be analyzed.
Errors in the method are due to:
• Losses due to the solubility of the precipitate
• Mechanical losses
• Gains due to co-precipitation
3. what is volatilization gravimetry?
★ Volatilization gravimetry involves separating the
components of our mixture by heating or through
chemical decomposition. This causes any volatile
compounds to separate, resulting in a change in
mass that we can measure.
4. It consists of measuring the components of the sample that are or may be
volatile, it can only be used if the analyte is the only volatile substance and use
is made of a selective absorbent or if the analyte is evaporated and the
corresponding measurements are made on the residue obtained. It is based on a
change of physical state to separate the compounds, for example:
-Moisture expulsion
-Ebulling to remove O2 and CO2
-Simple and fractional distillation.
This method can also include volatile treatments or reagents to obtain volatile
compounds.
6. The analyte is volatilized at a suitable temperature.
The volatile product is collected and weighed, or, the
mass of the product is determined indirectly by mass
loss in the sample.
The mass of the product is determined indirectly by
the loss of mass in the sample.
Types of volatilization methods
a) The one applied for water: water is quantitatively removed
from many inorganic samples by drying. In the direct direct
determination, it is collected in any of the various desiccant
solids and its mass is determined from the mass gained by
the desiccant. Mass gained by the desiccant. In the indirect
method the amount of water is determined by the loss of
mass of the sample during heating.
b) Applied for CO2: like the direct analysis for water, the
mass of CO2 is determined by the increase in the mass of an
absorbent solid. In the mass of an absorbent solid
How is the volatilization of an analyte
obtained?
7. EXAMPLE
Examples include the expulsion of
moisture to dry a sample, the calcination
of a residue to remove ammonium salts,
the boiling of a solution to remove
dissolved oxygen, carbon dioxide, etc.
8.
9. Direct method
Occurs if we evaporate the
analyte and pass it through
an absorbent substance that
has been previously
weighed so that the weight
gain corresponds to the
analyte sought.
Indirect method
It is given if we volatilize
the analyte and weigh
the residue after
volatilization so the
weight loss suffered
corresponds to the
analyte that has been
volatilized.
10. The calculations associated with gravimetric
methods of analysis are based on
stoichiometry and the results are determined
from
Mass of the sample.
Mass of the product (or analyte) of known composition.
The concentration of the product is expressed in percent of
analyte.
11. Determination of the sodium bicarbonate hydrogen content in antacid
tablets by indirect volatilization of carbon dioxide. The question is:
could CO2 be volatilized and the content of sodium hydrogen
bicarbonate in the antacid tablets be determined by indirect
volatilization treated with dilute sulfuric acid in a solution, where
NaHCO3(ac) + H2SO4(ac) CO2 (g) + H2O(l) + NaHSO4(ac)
EXAMPLE
12. This will only be possible if the reaction containing sulfuric acid and bicarbonate is carried out in a flask
initially connected to a tube containing sulfate. Bicarbonate is carried out in a flask initially connected to
a tube containing calcium sulfate (CaSO4) to obtain pure carbon dioxide (CO2) in nitrogen, one has
(CaSO4) to get pure carbon dioxide (CO2) in nitrogen, the H2O vapor has to be removed from the initial
reaction.
H2O vapor has to be removed from the initial reaction. That is, these gases pass through the drying
tube containing CaSO4. Drying tube containing CaSO4 (Driedite).
Then, these gases are absorbed by an absorption tube (NaOH on a non-fibrous silicate (Ascarbide).
silicate (Ascarite)) containing the previously weighed adsorbent Ascarite II,
where carbon dioxide is retained, producing the reaction.
CO2 + 2 NaOH Na2CO3 + H2O
In conclusion, the gravimetric procedure for volatilization of the
products carbon dioxide (CO2) and water (H2O) is collected
on heavy sorbents. The mass mass is used as the analytical variable.
14. Bibliographic references.
Romero Bonilla, Í., & Dávila Dávila, K. (2015). Principios básicos de Química
analítica cualitativa: para estudiantes de Ingeniería Química.
https://www.docsity.com/es/gravimetria-por-la-volatilizacion/2494659/
Martínez, D. V. (2019, April). Efectos del QuitoMax y el Bayfolan Forte en el cultivo
de la habichuela (Vigna unguiculata). In 9na Edición de la Conferencia Científica
Internacional de la Universidad de Holguín
https://es.slideshare.net/Claudia-Lizeth/volatilizacion
DE, A. L. F. Y. P. (2012). Facultad de Estudios Superiores Cuautitlán (Doctoral
dissertation, UNIVERSIDAD NACIONAL AUTÓNOMA DE MÉXICO).
https://prezi.com/9kyjt6gyjm4y/gravimetria-por-volatilizacion/?fallback=1
