Dissolving iron in HCl, unknown product

  • Thread starter Thread starter mishima
  • Start date Start date
  • Tags Tags
    Hcl Iron Product
Click For Summary

Discussion Overview

The discussion revolves around the process of dissolving iron in concentrated hydrochloric acid (HCl) and the unexpected formation of a solid product. Participants explore the chemical reactions involved, the nature of the resulting substances, and the implications for determining the purity of iron (III) chloride for a specific application in a chemistry class.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expected to obtain iron (II) chloride, which would convert to iron (III) chloride over time, but instead observed a light greenish solid accumulating at the bottom of the beaker.
  • Another participant noted that the solubility of iron (II) chloride at room temperature suggests that precipitation could occur due to the excess chloride ions present in the solution.
  • The purity of the iron strip used was questioned, with one participant mentioning that it was a Flinn Scientific product that may have had slight rust, potentially affecting the reaction.
  • A later reply proposed that the solid observed might be ferrous chloride (tetrahydrate), suggesting a possible identity for the precipitate formed.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the identity of the solid product formed or the implications of the iron's purity on the reaction outcomes. Multiple competing views remain regarding the nature of the precipitate and the chemical processes involved.

Contextual Notes

There are limitations regarding the assumptions about the purity of the iron strip and the exact conditions under which the reaction occurred, including the concentration of reactants and the presence of impurities.

mishima
Messages
576
Reaction score
43
My class needed some iron (iii) chloride to determine the purity of some aspirin they synthesized, so I thought I might try making some. I left a strip of iron in concentrated HCl for a few nights under the fume hood. I was expecting a liquid with iron (ii) chloride to result, which would then gradually turn into iron (iii) chloride with time.

What I got was a light greenish snow-like solid substance accumulating in the bottom of the beaker (regrettably did not get any pictures). I filtered this off, but now I am wondering exactly what it was. Nothing went into the beaker but the 9 g Fe strip and about 100 ml of 12 M HCl.

The solution I ended up with performs like iron (iii) chloride, it will turn salicylic acid a purplish color. It is a very dark brown liquid that leaves yellowish trails on the sides of its container. I'm going to do a titration to get its exact concentration.

I should've had a bunch of excess HCl since Fe was limiting the reaction. Could I have saturated the solution with iron (ii) chloride?
 
Chemistry news on Phys.org
According to wiki solubility at room temp. is around 70g/100 mL, and you are below 20g/100 mL. Then, you have a huge excess of Cl-, so I wouldn't rule the precipitation out.

How pure was the iron?
 
It was a Flinn Scientific iron strip, which I believe are intended (or sold as) electrodes. I cut it up using snips. The package had been opened before, and some other pieces were showing very slight spots of rust. The one I cherry picked did not, though I did not look using magnification.

Additionally, this billowing solid was noticeable long before the strip had completely dissolved.

I will double check the packaging tomorrow morning, but I can't recall any quantitative indication of purity.
 
Sounds like you got ferrous chloride (tetrahydrate) at the bottom.
 

Similar threads

Making Iron (II, III) Oxide, Fe3O4: Experiments and Substitutes
  • · Replies 6 ·
Replies
6
Views
39K
Will Cast Iron dissolve in dil. or conc. acid?
  • · Replies 4 ·
Replies
4
Views
21K
A2 OCR Planning Help: Determine Chlorine Concentration by Back Titration
  • · Replies 2 ·
Replies
2
Views
3K
Predicting Redox Reactions: Help with Lab Questions and Product Predictions
  • · Replies 2 ·
Replies
2
Views
5K
Calculate Mass of Iron in Erlenmeyer Flask Experiment 8
  • · Replies 5 ·
Replies
5
Views
3K
Checking Answers of Chemistry Assignment
  • · Replies 1 ·
Replies
1
Views
8K
Mastering Net Ionic Equations: Easy Tips and Common Mistakes to Avoid
  • · Replies 3 ·
Replies
3
Views
18K
Mastering Net Ionic Equations: Tips and Common Mistakes to Avoid
  • · Replies 2 ·
Replies
2
Views
4K