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Non Life Sciences => Chemistry => Topic started by: Adam-2020 on 02/09/2022 18:01:30

Title: How to convert lye water into solid
Post by: Adam-2020 on 02/09/2022 18:01:30

Hi

I have made lye watere from wood ash. How can I convert it from liquid to solid? I mean to get a salt

Title: Re: How to convert lye water into solid
Post by: Bored chemist on 02/09/2022 18:04:35

If you leave the liquid in a shallow dish most of the  the water will evaporate and will leave a strong solution of crude potash behind.
You can boil off the remaining water but be careful what sort of container you use.

Title: Re: How to convert lye water into solid
Post by: Adam-2020 on 02/09/2022 18:17:43

Quote from: Bored chemist on 02/09/2022 18:04:35

If you leave the liquid in a shallow dish most of the  the water will evaporate and will leave a strong solution of crude potash behind.
You can boil off the remaining water but be careful what sort of container you use.

I think i will use a stainless steel or aluminum pot. Which is bett? and the resultant salt will it be potasium or sodium hydroxide?

Title: Re: How to convert lye water into solid
Post by: Bored chemist on 02/09/2022 19:00:27

Aluminium will dissolve in hot alkali.
Cast ion or stainless steel are the best options.
You will not get any hydroxide because it would react with carbon dioxide in the fire and or the air to make carbonate.
Unless you picked some very unusual plants, you will have potassium carbonate.

Title: Re: How to convert lye water into solid
Post by: JesWade21 on 07/09/2022 08:22:22

I filter out as much ash as possible from the lye water before boiling it. Allow it to settle for a few minutes before carefully pouring it into another pot and repeating the process several times. Once the water has clarified and is no longer murky, I place it in a frying pan and boil the water off, allowing the lye crystals to form once all of the water has evaporated.

Then I just scrape everything off the pan.

Title: Re: How to convert lye water into solid
Post by: Bored chemist on 07/09/2022 08:38:09

Quote from: JesWade21 on 07/09/2022 08:22:22

Assuming you used room temperature water, 3 teaspoons of lye dissolved in one cup of water would not produce enough heat to bring the water to a boil. You dissolved approximately.79 mol NaOH in approximately 237 mL water, releasing approximately 35 kJ into the system. This will raise the temperature of the water by about 30 degrees Celsius, which will be noticeable but will not cause any bubbling if the water isn't already hot. I'm also significantly overestimating the total number of moles NaOH because lye is a granulated solid and I didn't account for the air percentage of the total volume (I converted tsp straight to cm3 because this is just a rough estimate), As a result, it would be closer to a T of 25-27 degrees C. Regardless, such a small temperature change will not result in boiling or bubbling.

What question did you think you were answering?

Title: Re: How to convert lye water into solid
Post by: JesWade21 on 07/09/2022 09:26:05

Quote from: Bored chemist on 07/09/2022 08:38:09

What question did you think you were answering?

Sorry for my mistake, I was just confused with some similar question at any other platform.