Reaction of Chlorine with Iron
Iron wool heated to glowing red reacts vigorously with chlorine gas in a flask. The product is red-brown solid iron(III) chloride. Evidence for this product is the fact that when it is dissolved in water a yellow-orange solution results. This is characteristic of iron(III) ions in aqueous solution.
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Keywords
combination reaction, descriptive chemistry, enthalpy/heat, evidence of chemical reaction, exothermic process, halogens/halides/hydrohalic acids, iron, redox reaction
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(QuickTime 3.0 Sorenson, duration 53 seconds, size 3.6 MB)
A ball of iron wool is heated and placed in a flask containing chlorine gas. The iron reacts vigorously with the chlorine to form a cloud of iron(III) chloride. After several minutes the iron(III) chloride formed by the reaction settles to the bottom of the flask. When the flask is rinsed with water the iron(III) chloride dissolves forming an orange solution.
 Iron wool is heated. |
 Iron reacts vigorously with chlorine. |
 Iron(III) chloride formed by the reaction settles. |
 The flask is rinsed with water. |
 The iron(III) chloride dissolves... |
 ...forming an orange solution. |
Additional still images for this movie
Discussion
Iron and chlorine do not react rapidly at room temperature, but if the iron is heated, the reaction is vigorous. Two products are possible, iron(II) chloride and iron(III) chloride. The iron is seen to be oxidized all the way to iron(III) chloride because the product is rust colored and when dissolved in water has the yellow-orange color characteristic of aqueous iron(III) ions. This color is actually due to the monohydroxo complex of iron(III) ion. Hexaaquoiron(III) ion is sufficiently acidic that it loses one proton unless the solution has been acidified with a stronger acid.
Demonstration Notes, Warnings, Safety Information, etc.
Exam and Quiz Questions
1. What observable evidence indicates that a chemical reaction has taken place?
2. Classify the reaction shown in the video as combination, decomposition, exchange, acid-base, or redox. (The reaction may fall within more than one of these categories.)
3. Is the reaction shown exothermic or endothermic? Cite observations that justify your choice.