Experiment to Learn the Amount of Iron in Iron Tablets

• GABRIELA CARUSO KANDIR

1.1 What is Topic area you are investigating in to: Prepare and standardize a potassium permanganate solution and use it to determine the amount of iron (II) in iron tablets

2. What is your title: Analyze the actual amount of iron (II) present in a tablet of iron supplement
3. What is your Aim: Demonstrate if iron supplements have the adequate levels of iron (II) by studying if the claims in supplement bottles are correct or not.

2.1, 2.2, 2.3 Objectives: Measure the amount of iron (II) in supplement tablets through performing a redox titration reaction

2.1, 2.2, 2.3 Extraneous variables (contaminants): Permanganate solutions tend to decompose with time, causing a change in concentration. To overcome this variable it is important to standardizing the KMnO₄ solution.

Sulfuric acid should always be in excess to avoid insoluble brown manganese oxide (MNO₂) formation.

4. Introduction and/or rationale: Iron is a mineral that is naturally present in many foods, added to some food products and available as a dietary supplement. Ion is an essential component of hemoglobin, an erythrocyte protein that transfers oxygen from the lungs to the tissues. As a component of myoglobin, it provides oxygen to muscles. Iron also supports the metabolism and is necessary for growth, development, normal cellular functioning, and synthesis of some hormones and connective tissues.

In case of iron deficiency the human body cannot make enough healthy oxygen carrying red blood cells (erythrocyte), and a lack of those cells is called iron deficiency anemia.

Without healthy red blood cells it is not possible to transport enough oxygen through the body, and without oxygen there is fatigue. Exhaustion can affect everything, from brain function to the ability of the immune system to fight infectious.

The daily requirements for iron depends o age, gender and overall health. Starting at adolescence, a woman’s daily iron needs increases. Women need more iron because they lose blood each month during their period. That is why the NHS advices women from ages 19 to 50 to get 14.8 mg of iron each day, while men the same age need to ingest only 8 mg. For the same age group the United States department of health and the Heart and stroke foundation in Canada recommends a even higher daily intake of 18 mg of iron per day.

Most women will ingest their daily iron needs through their normal meat and vegetables diet. Some groups, such as vegetarians, pregnant women, or those with higher blood loss (blood donations, heavy menstrual periods, stomach or intestine conditions among other examples) may need iron tablets supplementation on top of their regular diet. This is due either because of a decrease in ion intake (diet) or absorption or there is an increase in the iron needs (such as pregnancy or breast feeding for example).

An iron deficiency and consequent anemia will lead to signs of short of breath, fast heartbeat, cold hands and feet, craving for strange substances such as dirt or clay, hair loss, sores at the corner of the mouth and sore tongue.

As mentioned before, in some cases of iron deficiency eating a diet that is high in iron-rich foods such as fortified cereals, read meat, dried fruit and beans may not be enough to give the required needs, in this case a doctor may recommend iron supplement, but unlike some supplements, when the subject is iron, more is definitely not better. Adults shouldn’t take any more than 45 mg of iron a day unless they are being treated with iron under close medical supervision.

2.4 Analysis of source material: Oxidation-reduction (redox) reactions are one of many chemical reactions. Redox usually involves the transfer of electrons. Titration is the volumetric measurements of a solution of know concentration when it reacts completely with a measured volume or mass of another substance. The analysis of present iron in a supplement tablet can be done by a redox titration reaction.

Iron (II) ions can be ionized to ion (III) ions by potassium permanganate in acidic solution. For the redox titration reaction one of the most commonly strong oxidizing agent is used, the potassium permanganate (KMnO₄). Iron (II) will be oxidized to iron (III) and the potassium permanganate will be reduced to Manganese.

MnO₄^–+8H⁺+5Fe²⁺Mn₂+4H2O+5Fe³⁺

As the Potassium permanganate doesn’t require an indicator to signal the end-point of the titration, it has a unique advantage among titrants. In an acidic condition the deep purple solution of manganite ions is reduced to a very pale pink solution of manganese ions. This solution is so pale as to appear colorless when dilute and, in practice, the marked difference in color between these two oxidation states is useful as an end-point for this redox reaction.

The manganite ion accepts electrons and is reduced to colorless Mn ²⁺ ions according to the following half-equation:

The potassium manganite solution is added from the burette to the solution of the reducing agent and is immediately decolorized. As soon as the reducing agent is used up, the next drop of potassium manganite solution is not decolorized therefore coloring the solution as a pale purple color. The end-point is the first appearance of this purple color. The acid used to provide H⁺ is dilute sulfuric acid.

1. Risk assessment:

2.1 List the equipment and chemicals/reagents you would use to undertake your experiment:

Potassium Permanganate

Burette and Clamp with white numbering

Iron sample (Iron supplement tablets- 3 different samples)

Appropriate glassware

3M sulfuric acid (H₂SO₄)

Magnetic stirrer

3 100- 150 mL beakers

2.1 How you would carry out the experiment including the use of equipment and what chemicals/reagents you would use?

preparation of the Iron tablet sample:

1. Clear three 100-150 mL beakers with soap and water. Rinse with several small portions of distilled water
2. Directly into each beaker, weigh approximately 0.5 grams of iron sample.
3. Add 15 mL of distilled water to each sample and stir to dissolve the solid
4. Add 8mL of 3M sulfuric acid, to each sample. This step is needed to provide the hydrogen ions, which are required for the reduction of the permanganate ion.

Titration of the Iron sample Potassium Permanganate:

1. Obtain approximately 55 mL of the standardized potassium permanganate solution (KMnO₄), and record the exact concentration of the KMnO₄ solution.
2. Prepare the buret by cleaning, rinsing and filling with potassium permanganate solution.
3. Record the initial volume reading to the nearest 0.01 mL
4. Titrate each sample to the endpoint (first appearance of permanent- at leat 10 seconds-, pale pink color). Record the final buret reading
5. The mass of iron in each sample can be determined from the volume of KMnO₄ required to titrate. This is possible through determining the moles of KMnO₄ used, and a balanced equation.

2.1 How will you collect and record the data: data will be collected from the 3 samples in a table with the initial and final volume of titrate. A note on the exact concentration of the KMnO₄ solution will also be present in the results sheet.

2.1 How will you Analyze results: The mass present in each sample will be determine through the calculation of the concentration of a reagent from the titration results. Results will be compared with the claims from supplement bottles to verify if the amounts are similar or the claims are incorrect.

2.1 How will you present your data?: Data will be presented with tables showing the amount of iron (II) in the three samples followed by a comparing graph of the quantities found in the tests with the claims in the iron supplement bottles.

4. References:

Reference List:

Heart and Stroke Foundation (2015) Nutrients for women [Online] Available from: < http://www.healthcheck.org/page/nutrients-women> (Accessed on 22 April 2015)

NHS (2015) Vitamins and Minerals- Iron [Online] Available from: < http://www.nhs.uk/Conditions/vitamins-minerals/Pages/Iron.aspx (Accessed on 22 April 2015)

Centers for disease control and prevention (2011) Iron and iron deficiency [Online] Available from: < http://www.cdc.gov/nutrition/everyone/basics/vitamins/iron.html (Accessed on 22 April 2015)

Webmed (2011) What You Need to Know About Iron Supplements [Online] Available from: < http://www.webmd.com/vitamins-and-supplements/lifestyle-guide-11/iron-supplements?page=3 (Accessed on 22 April 2015)

National Institute of Health (2015) Iron [Online] Available from: < http://ods.od.nih.gov/factsheets/Iron-HealthProfessional/#h2 (Accessed on 22 April 2015)

AQA (2009) 2 Inorganic Chemistry PSA10 Carry out a redox titration [Online] Available from: < http://filestore.aqa.org.uk/subjects/AQA-2420-W-TRB-PSA10.PDF (Accessed on 23 April 2015)

A-level Chemistry web (2015) Redox titration [Online] Available from: <http://alevelchem.com/aqa_a_level_chemistry/unit3.6/inorg01.htm (Accessed on 23 April 2015)

Collin College (2010) Determination of Iron in Dietary Supplement through Redox Titrations [Online] Available from: < http://www.collin.edu/chemistry/Handouts/1412/Redox Titration Experiment.pdf> (Accessed on 23 April 2015)

Chemistry Lab Mouse A2 (2008) Practical: Determination of the Percentage of Iron in Iron Tablets [Online] Available from: < http://sustainability.sellafieldsites.com/resources/labmouse/chemistry_a2/3204.php> (Accessed on 24 April 2015)

Northern Virginia Community College (2014) Chemistry 111 Lab- Redox Titration [Online] Available from: < http://www.nvcc.edu/alexandria/stb/chm/111/111.08RedoxTitrationSpring2015.pdf > (Accessed on 24 April 2015)

Boundless (2014) Redox titrations [Online] Available from: < https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/aqueous-reactions-4/oxidation-reduction-reactions-48/redox-titrations-248-1533/> (Accessed on 24 April 2015)

Winona State University (2010) Determination of Iron by Redox Titration [Online] Available from: < http://course1.winona.edu/cmiertschin/213/inquiry_lab/exp10_fe_redox.pdf (Accessed on 24 April 2015)

Braemar College (2015) Internal Assessment Guidelines & Unit Timeline [Online] Available from: < http://vinkichemistry12.weebly.com/uploads/2/5/2/1/25219856/course_description_-_unit_3_2015.pdf> (Accessed on 24 April 2015)

Risk assessment services (2008) Hazard Communication Sheet SULPHURIC ACID 90-100%w/w [Online] Available from: < http://www.riskassessmentservices.co.uk/HazCom/Sulphuric Acid3.pdf> (Accessed on 24 April 2015)

TAQ 2 Time Frame of the investigation if the experiment was to be carried out:

• 3 days for background research
• 2 days to write an introduction, reference list
• 1 day to arrange chemicals, samples and equipments to do the experiment
• 1 day to do the experiment
• 1 day to analyze collected data
• 2 days to write results, build tables and graphs and write a conclusion and abstract
• Total 10 days to finalize carry out the research project