To determine how much iron metal is in a sample of Total cereal and whether this is consistent with the manufacturer’s claims. To understand the difference between elements in their elemental state and ionic forms.
It is becoming more and more popular for people to want to know what is actually in the food products they purchase, such things like the sodium, iron, vitamin and minerals that are in their grocery items. By law, food companies are required to print this information on the label of their product. Although the information is there, is it accurate?
When reading the label on a box of Total cereal, one would read that there is 40mg of potassium per serving. Now for the unknowing, potassium is a highly reactive metal, made of potassium atoms, that will produce a potentially explosive hydrogen gas when it comes in contact with water. We know that when we eat Total cereal that we need not fear for our lives, so how is it possible to have 40mg of a hazardous element in your cereal? The label information is a little misleading. The label states that there is 40mg of potassium, when in fact there are
40mg of the potassium ion, K + cations not the elemental form of potassium. Ions in any element including potassium have very different properties that their elemental forms.
The labeling also states that it contains 100% of the daily recommended intake of iron, which according to netrition.com is 18mg based on a 2000 calorie intake diet for children and adults starting at 4 years of age. Unlike potassium, iron in its elemental form is not as reactive and the cereal does indeed contain iron in its elemental reduced form.
Elemental iron is ferromagnetic, meaning it is attracted to a magnet, and there is enough iron in one flake of Total cereals that the flakes themselves can be moved by a magnet. Your task is to take a sample of Total cereal and extract and determine the mass of the total iron metal present.
Iron is not the only ferromagnetic element in the Periodic Table, so it is very possible that the extracted metal may contain more than just iron alone. So the sample must be tested to determine if it is actually iron and not some other element or contaminant that the manufacturer had inadvertently added. Chemical tests can be done to determine if the metal is indeed iron of a mixture of other elemental metals.

1.
Obtain a 10.0g sample of the Total cereal. In order to completely release the iron metal from the flakes, the cereal must be grinded into a powder. Do so with a mortar and pestle, once ground place in a beaker with distilled water to create a slurry solution.
2.
To completely extract the iron metal from the slurry use a magnetic stirrer bar and plate. Before continuing, determine the mass of the dry, clean magnetic stirrer, this will be necessary for later use. Place the beaker on the magnetic plate with the magnetic stirrer in the mush. When adjusted to the appropriate setting (depending on the viscosity of your slurry, this setting is approximately 7-8) the stirrer will begin to turn within the beaker and while doing so it will also begin to collect small pieces of iron metal as it moves through the slurry.
3.
Once the optimal amount of iron metal has collected on the stirrer, remove from slurry and clean.
A) Remove excess cereal from stirrer by spraying with distilled water.
(WARNING: do not do this over the sink, you do not want to risk washing your sample down the drain)
B) Rather than wasting several hours waiting for the bar and the sample to dry, a quick washing with the volatile organic solvent, acetone will remove the water, leaving a small amount of acetone that will evaporate within a few minutes.
4.
Determine the mass of the rod and the sample. (The mass of the sample can be determined by subtracting the mass of the dry, clean rod from the total mass of the rod and sample combined.)
5.
In order to test for iron and nickel the following must be preformed to prepare the solution: 1) place the stirrer bar, still coated with magnetic material in a medium sized test tube and add 1ml of concentrated HCl
(aq)
hydrochloric acid, all under the fume hood. FeCl
2 is formed in the solution as one of the products with the other being hydrogen gas. 2) Once the reaction is complete, the resulting solution should be diluted with 3ml of distilled water.
6.
The tests for iron and nickel need to be performed in a ceramic plate with wells. Let’s begin first by testing for iron: Place 1 drop of the prepared solution in one well. Also place 1 drop of the provided Fe 3+ ion solution in another well; this will be used as our control. Add hydrogen peroxide, which will oxidized the Fe 2+ ions to Fe 3+ ions in the solution allowing the color change to be better observed. To both wells add 3-4 drops of
KSCN
(aq) potassium thiocyanate, observe. A blood red color is produced if iron is present.
7.
Record your observations.

8.
In order to test for Ni 2+ ions (Nickel) this requires the solution to be basic by adding ammonium hydroxide solution, NH
4
OH
(aq)
.
Begin by adding 2 drops of your original solution into an empty well. Also add 2 drops of Ni 2+ ion to another well, this will be your control.
9.
Add 4 drops of 6 M ammonia to each well.
10.
Test for pH with a red litmus paper, place litmus paper on a watch glass, dip a clean stirring rod in the solution and touch it to the litmus paper; clean stirring rod before dipping into second solution. If the paper turns blue, the solution is basic. You must then continue to add 2 drops of DMG, dimethylglyoxime to each well to test for nickel. This will produce a pink precipitate if nickel is present.
11.
Record and interpret your observations before and after each addition of DMG.
Mass of dry, clean magnetic rod:
4.25 grams
Mass of rod and magnetic substance:
4. 2744 grams
Mass of magnetic substance:
0.0244 grams
Iron Testing
SUBSTANCE
Magnetic Substance
Fe 3+ ion
Nickel Testing
SUBSTANCE
Magnetic Substance
Ni 2+ ion
REACTION OBSERVED
Red Solution (Positive)
Blood-Red Solution (Positive)
REACTION OBSERVED
Clear Solution (Negative)
Pink Solution (Positive)

If the suggested daily intake of Iron is 18mg and Total cereal claims to have 100% of the iron needed for one day in a 30mg serving, how much iron should be present in your 10.0mg sample?
18𝑚𝑔
30𝑚𝑔
×
𝑋𝑚𝑔
10𝑚𝑔
=
180𝑚𝑔
30𝑚𝑔
= 𝑋, 𝑋 = 6𝑚𝑔 ≈ 0.006𝑔
Did your sample contain this much iron?
Our sample contained more magnetic substance. Total= 0.0244g. And based on our experiment iron was the only magnetic substance present. After speaking with the professor we became aware that the nickel test should have tested positive. For some reason ours tested negative.
Is Total cereal’s labeling inaccurate based on your experiment?
Based on our experiment, Total cereal very well could have a correct label. But based on the professor’s explanation and the inaccuracy of our tests, Total’s label would be incorrect because the magnetic substance found in Total cereal not only contains iron, but also contains nickel.
4.2744g – 4.25g = 0.0244g
18𝑚𝑔
30𝑚𝑔
×
𝑋𝑚𝑔
10𝑚𝑔
=
180𝑚𝑔
30𝑚𝑔
= 𝑋, 𝑋 = 6𝑚𝑔 ≈ 0.006𝑔
Based on our experiment, Total cereal very well could have a correct label. But based on the professor’s explanation and the inaccuracy of our tests, Total’s label would be incorrect because the magnetic substance found in Total cereal not only contains iron, but also contains nickel.