However, while it looks very simple and straightforward, in fact to be accurate we have to take into account several factors. The most obvious one concerns all permanganate titrations - when permanganate is used as a titrant we should use different technique to read volume of liquid in the burette. The meniscus is not visible, as the solution is opaque - thus we have to look at the top of the liquid. However, this procedure works only if the excess of SnCl2 is small - otherwise mercury cations can be reduced to metallic mercury, which can reduce permanganate.
Chemistry Laboratory Successor of Basic Chemistry Lab-Include-Acid-base titrations, alkali solutions, Amperometry, Colourchange, Complexometric, titrations, Conductance, equivalence point, Henderson-Hasselbalch equation, History, indicator error, indicators, isothermal titration, pH curve, pH indicator, pH meter, potentiometer, Precipitation, Redox titrations, Spectroscopy, Thermometric titrimetry, titrant, Titration, Titration curve, titration methods, titrator, Volumetric analysis ,zeta potential titration Saturday, October 27, Objective: In this experiment, you will use the quantitative technique of spectrophotometry to determine the mass of iron contained in a commercially available vitamin tablet.
These two facts about iron are not unrelated as nature has found it logical to adapt this plentiful element to perform a variety of functions.
The fact that iron has two readily accessible oxidation states, Fe II and Fe IIIalso contributes to its usefulness as an active component of proteins. The average adult human body contains g of iron.
In human beings, the majority of iron present is found in the blood in a protein called hemoglobin. The function of this protein is to transport oxygen from the lungs to the various tissues in the body where it is used to produce energy.
One of the byproducts of this metabolism, carbon dioxide, is then transported back to the lungs by hemoglobin. Both the oxygen and carbon dioxide molecules bind to the iron ion present in hemoglobin during transport.
Humans obtain the iron necessary for the formation of hemoglobin from their diet in foods such as meat and leafy, green vegetables. When the dietary intake is deficient in iron, a condition called anemia results.
Someone who is anemic exhibits a lack of energy and often unusually pale skin tone the red color of blood is also a result of the presence of iron in hemoglobin.
Dietary supplements of iron in the form of vitamin tablets can be administered to help alleviate this condition. Spectrophotometric Analysis One of the most common techniques used in the quantitative analysis of samples for a specific chemical substance is called spectrophotometry.
In spectrophotometry, the amount of electromagnetic radiation absorbed by a sample is measured with an instrument called a spectrophotometer, and this absorbance is related to the concentration of the species for which the sample is being analyzed.
Molarity is represented by a capital, M: You should read all of Section V. Because the molar absorptivity value is not always a known quantity, a calibration curve is often constructed from a series of standard solutions.
A standard solution is one in which the concentration of the species being analyzed is known. The absorbances of several standard solutions are measured, and these values are plotted as a function of the concentrations of the solutions. The absorbance of a solution of unknown concentration can then be measured with the spectrophotometer, and this value can be used in conjunction with the calibration curve to determine the concentration of this solution.
Analyzing for iron spectrophotometrically In this experiment, you will spectrophotometrically analyze a commercially available vitamin tablet in order to determine the quantity of iron that is contained in the tablet.
To do this, the iron will first be converted into a form that absorbs radiation in the visible region. This conversion will be done by reacting the iron with an organic compound called 1,phenanthroline. The structure of this molecule is shown in Figure 1.
It reacts with Fe II to form an ionic compound that contains one iron ion and three 1,phenanthroline molecules the structure of this compound is also shown, in Figure 2. The color of this compound in solution is bright red-orange; consequently, it absorbs light very strongly in the visible region at a wavelength of nanometers.
You will react 1,phenanthroline with a vitamin tablet that has been dissolved in hydrochloric acid. In order for this reaction to occur, the iron ions that are present must be in the Fe II oxidation state.
Since Fe II is easily oxidized to Fe III in the presence of acid and water, a reducing agent called hydroquinone is added to the solution. In addition, it is important that the acidity of the solution is carefully controlled or compound 1 will not form; the presence of sodium citrate in solution will neutralize some of the acid and maintain the proper pH.
The resulting solution will be diluted to an appropriate concentration and its absorbance measured. A spectrophotometric calibration curve will then be constructed from a series of standard solutions which contain known concentrations of the iron—1,phenanthroline compound 1.
The concentration of iron in your sample solution, and thus the amount of iron contained in the vitamin tablet, cansubsequently be calculated. Obtain 25 mL of 6 M hydrochloric acid in a mL beaker and place the ground vitamin tablet in this solution.
Swirl the beaker and wait a few minutes for evidence of a reaction. After the initial reaction has subsided, place the beaker on a hot plate in a fume hood, cover with a watchglass and heat to boiling. Boil the mixture for 15 minutes. You may need to add more distilled water during the boiling period if the volume falls below about 15 mL.
Remove the beaker from the hot plate and rinse the bottom of the watchglass using a wash bottle, catching the rinse water in the reaction beaker. G directly into a mL volumetric flask. Rest the funnel in a wooden funnel holder. While the solution is filtering, heat some distilled water in a mL beaker on a hot plate.Iron pipes offer the most abundant source for the iron in our water.
The K sp of Fe(OH) 3 is x 10 Calculation yields a concentration of Fe 3+ in neutral water to be so low as to be undetectable -- on the order of one part iron per one quintillion parts of water (10 ). Zomorph capsules as % of all twice daily modified-release morphine sulphate.
Ferrous fumarate mg modelling suggests that titration with simvastatin 80 mg.
Warning Accidental overdose of drugs that have iron in them is a leading cause of deadly poisoning in children younger than 6 years of age. Keep away from children. If this medicine (iron tablets and capsules) is taken by accident, call a doctor or poison control center right away.
Save your standard solutions for the next part of the experiment that follows: Determination of Soluble Iron in a Commercial Iron Supplement Tablet/Pill/Capsule. CH Pre-Lab Problems. Most vitamin tablets contain iron in the form of ferrous fumarate, [Fe 2+ (C 4 H 2 O 4) 2-].
Spectrophotometric Analysis Spectrophotometry is one of the most common techniques used in quantitative analysis of samples for a specific chemical component. Atomic Absorption Spectroscopy. timberdesignmag.com, 9/10/96 PM Notice The information contained in this document is subject to change without notice.
BC - Analysis of Hair: Copper, Iron, Magnesium, Zinc, Lead BC - Analysis of Diet: Antimony, Cadmium, Chromium.