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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: FGP on December 31, 2013, 07:11:48 AM

Title: anticaking agent in salt
Post by: FGP on December 31, 2013, 07:11:48 AM

Note the following:
The reaction with hydrochloric acid is as follows:
6 HCl + K3[Fe(CN)6] → 6 HCN + FeCl3 + 3 KCl

Potassium hexacyanoferrate has an E number in UK of E536. The Sodium salt is more commonly used (E535) in ordinary 'table' salt.

Does it not strike anyone as odd that the above reaction MIGHT occur? I have no idea of the conditions under which the reaction would occur but the above equation quite frightens me.
Any opinions anybody.
Fred.

Title: Re: anticaking agent in salt
Post by: Borek on December 31, 2013, 08:08:04 AM

If the pH is low enough, and if the concentration of Fe(CN)₆^3- is high enough, yes, some HCN will be liberated. But you would have to eat several kilograms of the kitchen salt at once for the HCN amount to be dangerous - and once you will eat that amount of salt, HCN would be the least of your problems.

Title: Re: anticaking agent in salt
Post by: DrCMS on December 31, 2013, 10:02:30 AM

I'm pretty sure the condition in the human gut are not sufficient to release any HCN from potassium ferricyanide.  It is only classified as "harmful if swallowed" for this reason. 

Title: Re: anticaking agent in salt
Post by: FGP on January 01, 2014, 05:15:40 AM

Thanks for two replies as above. I agree with both comments but nevertheless I have concern that such a compound finds use in food. I have so far been unable to find the concentration of anticaking agent  in domestic salt  and the manufacturers seem a little cagey about it. I presume it finds use in road/grit/salt? Is 'iodised' salt still produced or is this a thing of the past?

Title: Re: anticaking agent in salt
Post by: billnotgatez on January 01, 2014, 08:08:22 AM

I was going to make a list of possible chemicals in edible salt, but there were so many I lost patience.

I used to wrongly think the additive was just clay/sand and an edible iodine compound.

http://en.wikipedia.org/wiki/Table_salt#Edible_salt

Title: Re: anticaking agent in salt
Post by: DrCMS on January 01, 2014, 04:26:01 PM

Quote from: FGP on January 01, 2014, 05:15:40 AM

Thanks for two replies as above. I agree with both comments but nevertheless I have concern that such a compound finds use in food.

Both myself and Borek have explained why it is not dangerous in salt and you agree with us but you're still concerned?  What exactly concerns you? 

Title: Re: anticaking agent in salt
Post by: FGP on January 02, 2014, 04:22:14 AM

Hi DrCMS.
 Thanks, perhaps my concern will disappear when I've established the concentration! I know my concern is not very logical, maybe  I just have an irrational fear of errors in manufacture and so forth. Doesn't a possible reaction that liberates HCN  worry you? I know it's unlikely to happen but I just have a kind of 'background' concern.