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Old 03-03-2009, 11:48 PM   #1
brewmonger
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This may seem like a strange question, but I'll explain why afterwards.

Is it normal for the pH of a beer to go down when you add salt to it? The pH measured at about 4.1 on an electronic pH meter. After I added some sea salt to a sample, it dropped to around 3.5.

Is this to be expected?

 
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Old 03-04-2009, 02:32 AM   #2
marc06
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I wouldnt think the seasalt would make the pH drop. Natural seawater has a pH of ~7.9-8.3 depending on where it comes from. The bicarbonate within seawater has a buffer capacity which would make the pH increase. There is nothing that I can think of within seawater/seasalt that would cause the pH to decrease.

 
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Old 03-04-2009, 03:09 AM   #3
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Certain calcium compounds (e.g. CaCl2 in sea salt) can liberate hydrogen ions reducing the pH. So, yes it is plausible.
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Old 03-04-2009, 03:17 AM   #4
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I would think Sodium Bicarbonate would be more abundant, which would act as a buffer

 
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Old 03-04-2009, 02:06 PM   #5
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Sea salt is ~98% NaCl. The remaining percent is small amounts of calcium sulfate (gypsum), magnesium chloride, calcium chloride, sodium sulfate, etc. The gypsum and calcium chloride can both reduce pH. I don't believe there is [virtually] any sodium bicarbonate in unadulterated sea salt.

However, 4.1 to 3.5 is a big drop, so assuming the meter to be correct, perhaps there is something else going on like CO2 coming out of solution and carbonic acid.
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Old 03-06-2009, 03:05 PM   #6
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Well, the beer was completely flat (no carbonation) when I added the salt, so I don't think it is because of carbonic acid being released.

The reason I am salting beer is because I am using it as a schmear for a washed-rind cheese.

btw, mods... This might be a thread that is appropriate for the new brewing science section.

 
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