EXPERIMENT 8
DETERMINATION OF Fe IN A FERUM SOLUTION BY GRAVIMETRIC ANALYSIS
ABSTRACT
The experiment which is Determination of Ferum In a Ferum Solution By Gravimetric Analysis is conducted in a Ferum solution.There are four parts in this experiment which are preparing a crucible,precipitation reaction,filtering and washing the precipitate and drying and weighing the precipitate.For Part A,which is preparing a crucible,a crucible was weighed together with its lid and was heated it in a furnace for 10minutes.Next,it was cooled in dessicator and was weighed accurately.For Part B,which is precipitation reaction,it is done by pipetting 25.0mL of Fe solution into 400mL beaker and add 25mL distilled water and cover with watch glass followed with boiling process.Next,1mL of concentrated HNO3 was added dropwisely.It was continued heating until the solution becomes clear.Next,the solution is diluted to 200mL with distilled water and the solution was boiled again.Cautiously,transfer the beaker to the fume cupboard and add 1:1 NH4OH into the solution slowly and with stirring,until it is in excess.It would noticed that when there is no more formation of the precipitate and also when the steam odour is smelled.From the experiment that is carried out,we can obtain the weight of precipitate in the determination of Fe in a Ferum solution.The weight of precipitate obtained in the experiment is 5.7952g.Besides,the mass of Fe that contains of 5.7952g of Fe2O3obtained is 4.0536g and the weight percent,%(w/v)of the analyte in the sample solution obtained in the experiment is16.2%.
OBJECTIVES
1.To determine the percentage of ferum in a ferum solution.
INTRODUCTION
In this technique, the analyte is converted to an insoluble form which can then be washed, dried, and weighed in order to determine the concentration of the analyte in the original solution. Gravimetry is applied to samples where a good precipitating agent is available. The precipitate should be quantitative, easily washed and filtered and is of in suitable quantity for accurate weighing. Therefore, gravimetry is regarded as a macro analytical technique. However, it is considered, when appropriately done, one of the most accurate analytical techniques. Also, Gravimetry is one of a few analytical methods that do not require standard solutions as the weight of precipitate is the only important parameter in analyte determination.
The concentration of Fe in a given solution will be determined in this experiment.Fe(II) is oxidised to Fe(III) and then precipitated as ferric oxide hydrates,Fe2O3.XH2O.To produce ferric oxide,Fe2O3,filtered,washed and dried the precipitate.We can calculate the mass of Fe in the solution since Fe2O3 is a stable compound.There is a long waiting period in this experiment that we need to manage time well.We should know what to do during the waiting period if we have rea and planned work well.
PROCEDURE
A.Preparing a Crucible
A crucible together was cleaned with its lid and it was heated in a furnace for 10 minutes.It was cooled in a desiccators and was weighed accurately.
B.Precipitation
25.0mL ferum solution was pipette into a 400mL beaker,25mL distilled water was added and was covered with watch glass.The solution was heated to boiling.Then 1mL concentrated HNO3 was added dropwisely.Heating was continued until the solution becomes clear.The solution was diluted to 200mL with distilled water and the solution was boiled again.The beaker was transferred cautiously to the fume cupboard and 1:1 NH4OH was added into the solution slowly and with stirring,until it is in excess.There no more formation of the precipitate was noticed and also when the steam odour was smelled.
C.Filtering and Washing the Percipitate
The precipitate was filtered by decantation using filter paper no. 41 without stirring the solution to ensure that most of the precipitate will be left behind in the beaker.Then the precipitate was washed with 30mL warm 1% NH4NO3solutions.The solution was poured into the filter funnel leaving behind most of the precipitate.This was repeated for another two times and finally all the precipitate was transferred quantitatively into the funnel.This could be done with the help of a rubber policeman and a wash bottle.Finally,the precipitate was washed in the funnel using warm distilled water and the filtrate was tested for chloride with acidic silver nitrate solution.The test should turned out positive,the washing process was repeated with more distilled water.
D.Drying and Weighing the Precipitate
The filter paper containing all the precipitate was transferred into the crucible that have prepared earlier on.The crucible was heated using a Bunsen burner with a small flame at the beginning until the paper has burned.The flame was increased and heating was continued for another 20 minutes.The heating process was repeated until a constant mass is obtained.Alternatively,if time did not permitted,the crucible containing the precipitate and filter paper were placed into a muffle furnace.The position of the crucible was recorded on the piece of paper at the furnace.The precipitate will be heated at 600 overnight.Once the crucible is cooled,the mass of the crucible and precipitate were weighed.The precipitate was poured into a plastic wrap,the plastic wrap was folded and stapled at the top so as to contain the precipitate inside the wrap.The product was submitted together with the report.The precipitate was ensured to be well contained in the plastic and did not leak out from the plastic wrap.
DISCUSSION
The experiment which is Determination of Fe in a Ferum Solution by gravimetric analysis is conducted in the experiment is to determine the percentage of Ferum in a Ferum solution.In this experiment,four parts of the experiment were conducted which are the preparation of a crucible ,precipitation reaction,filtering and washing the precipitate and drying and weighing the precipitate.In this experiment,the law was used,which is the law of conservation of mass.According to the law,the law of conservation of mass states that the matter can be interchanged from one form to another form.According to these law,the mixture can be separatedand the pure substances can be decomposed,but the total amount of mass of the substance remained constant.In this experiment,the determination of Fe in the unknown Ferum Solution is carried out by using gravimetric.
In this experiment,the process of retrieving of Fe in a Ferum solution usually consumes much time and can also lead to certain random error such as the personal error and the instrument error to be occurred.At this point,the equation that formed the precipitation is as follows:-
From the equation above,Iron (II) ion was oxidised to form Iron (III) ion to form the precipitate.The colour formed usually dark-brown colour when it reacts with NH4OH.The function of adding NH4OH is to distinguish the colour so that the presence is much visible.In the experiment,the mass of precipitate obtained is 5.7952g and the weight percent,%(w/v) of the analyte obtained in the experiment is 16.2%.besides,the Fe that contains 5.7952g of Fe2O3 is 4.0536g.
In this experiment,the steps was taken precautiously.For example,the addition of NH4OH must be carried out in the fume cupboard in order to prevent the smell of the compound to be distributed in the laboratory room.At this point,the steps in the precipitation reaction was taken chronologically,that is the steps were followed strictly in a gravimetric analysis in order to get the resulting analysis and to minimize the desirable outcome of the analysis.
CONCLUSION
In the nutshell,we can obtain accurately the weight of the precipitate and the percent weight,%(w/v) of the precipitate by using a gravimetric filtration (Gravimetric Analysis).In the experiment,the weight of the precipitate obtained is in the sample solution is 16.2%.Therefore,the percentage of Ferum in a Ferum solution is determined.
REFERENCES
https://www.dartmouth.edu/~chemlab/chem3-5/ionx2/full_text/intro.html
https://manoa.hawaii.edu/exploringourfluidearth/chemical/chemistry-and-gravimetric-analysis/determination-fe-in-a-ferum-solution/weird-science-types-water-sampler
http://www.scribd.com/doc/46545610/Gravimetric-analysis#scribd
UNIVERSITI TEKNOLOGI MARA
SHAH ALAM
No experiment:8
Title : Determination Of Fe In A Ferum Solution By Gravimetric Analysis
Name :Nur Syahirah binti Zainal Abidin
Student's number : 2014462292
Course :CHM 421
Group number :AS2463A
Lecturer's name :Puan Ruhani Ibrahim
Date of the experiment : 26 October 2015
Date of the report is due: 2 November 2015
