Extracting Citric Acid From Lemons
Summary
TLDRThis video demonstrates a DIY method to extract citric acid from lemons. The process involves juicing lemons, neutralizing with sodium hydroxide to form sodium citrate, then precipitating with calcium chloride to form calcium citrate. After vacuum filtration, sulfuric acid is used to revert it to citric acid and gypsum. The final step involves vacuum drying and recrystallization for pure citric acid crystals.
Takeaways
- ๐ **Juice Extraction**: The process starts by juicing lemons to obtain citric acid.
- ๐งช **Neutralization**: Sodium hydroxide is added to neutralize the excess acid in the lemon juice.
- ๐ง **Filtering**: The solution is filtered to remove any lemon debris.
- ๐ด **pH Adjustment**: The pH is raised to 9 to convert citric acid into sodium citrate, indicated by a color change.
- ๐ **Precipitation**: Calcium chloride is added to convert soluble sodium citrate into insoluble calcium citrate.
- โฑ๏ธ **Settling Time**: The solution is left to allow calcium citrate to settle.
- ๐ฆ **Vacuum Filtration**: Vacuum filtration is used to isolate calcium citrate, noting the requirement for a vacuum.
- โ๏ธ **Cold Water Rinse**: It's suggested to rinse the filtered calcium citrate with cold water for cleaner results.
- ๐ฎ **Discard the Filtrate**: The filtrate is discarded as it is not needed for further steps.
- ๐ **Reformation**: Sulfuric acid is used to convert calcium citrate back into citric acid and gypsum.
- ๐ง **Freezing**: The solution is frozen to form citric acid crystals.
- ๐ฌ๏ธ **Final Purification**: The citric acid crystals are purified by recrystallization and vacuum filtration with ice-cold water.
Q & A
What is the first step in extracting citric acid from lemons?
-The first step is to slice up and juice a few lemons.
How much lemon juice is required to begin the process?
-The process begins with the juice of an unspecified number of lemons, which is then poured into a 1000 milliliter beaker.
What is the purpose of adding a sodium hydroxide solution to the lemon juice?
-A sodium hydroxide solution is added to neutralize the excess acid in the lemon juice.
What is the role of the coffee filter in the process?
-The coffee filter is used to remove any lemon debris from the solution after the sodium hydroxide has been added.
Why is the pH of the solution adjusted to 9?
-Adjusting the pH to 9 converts the citric acid from the lemons into sodium citrate, which is indicated by the solution's color shifting to a deep orange.
What is the function of adding calcium chloride solution to the mixture?
-The calcium chloride solution converts the soluble sodium citrate into insoluble calcium citrate.
Why is vacuum filtration used to isolate calcium citrate?
-Vacuum filtration is used to isolate calcium citrate because it allows for a more efficient separation of the solid from the solution.
What is the significance of rinsing the filtered calcium citrate with cold water?
-Rinsing with cold water is important to remove any remaining impurities and to make future steps cleaner.
How does the addition of a dilute sulfuric acid solution affect the calcium citrate?
-Adding a dilute sulfuric acid solution reacts with the calcium citrate to reform citric acid and precipitate white calcium sulfate, also known as gypsum.
Why is the filtered solution cooked down to 10 percent of its initial volume?
-Cooking down the solution to 10 percent of its initial volume helps to concentrate the citric acid, making it easier to form crystals.
What is the purpose of placing the resulting solution in the freezer?
-Placing the solution in the freezer allows the citric acid to crystallize, which can then be collected.
Why is recrystallization performed off-camera?
-Recrystallization is performed off-camera to keep the video short, and it helps to form larger, purer crystals of citric acid.
What is the final step in obtaining pure citric acid crystals?
-The final step is to dry the crystallized citric acid on a small filter, pulling a vacuum to rinse the crystals with ice-cold water.
What was the yield of citric acid from the process described in the script?
-The final yield of citric acid was larger than what was shown in the video, as the process was done in batches.
Outlines
๐ Citric Acid Extraction Process
The script describes a process for extracting citric acid from lemons. It starts with juicing lemons and adding sodium hydroxide to neutralize the excess acid. The mixture is filtered to remove debris, and additional sodium hydroxide is added until the pH reaches 9, indicated by a color change to deep orange. This converts the citric acid to sodium citrate. A calcium chloride solution is then added to convert the sodium citrate into insoluble calcium citrate, which is allowed to settle. After vacuum filtration, the calcium citrate is treated with a dilute sulfuric acid solution to reform citric acid and precipitate calcium sulfate (gypsum). The citric acid solution is then concentrated and frozen to form crystals, which are purified through recrystallization and vacuum filtration with ice-cold water.
Mindmap
Keywords
๐กCitric Acid
๐กLemons
๐กSodium Hydroxide
๐กpH
๐กCalcium Chloride
๐กVacuum Filtration
๐กSulfuric Acid
๐กGypsum
๐กRecrystallization
๐กYield
Highlights
Extraction of citric acid from lemons begins with juicing them.
Juice is poured into a 1000 milliliter beaker.
10 sodium hydroxide solution is added to neutralize excess acid.
Solution is filtered through a coffee filter to remove lemon debris.
Additional sodium hydroxide is added until pH reaches nine.
Citric acid is converted to sodium citrate at pH 9.
Strong calcium chloride solution is added to form insoluble calcium citrate.
An hour is given for calcium citrate to settle out of solution.
Vacuum filtration is used to isolate calcium citrate.
A cold water rinse of filtered calcium citrate is recommended for cleaner results.
Filtered calcium citrate is transferred to a fresh beaker.
A dilute sulfuric acid solution is used to reform citric acid and precipitate calcium sulfate.
Calcium sulfate, also known as gypsum, is formed.
Filtered solution is kept, and gypsum is discarded.
Solution is reduced to 10 percent of its initial volume.
Citric acid crystals are formed by freezing the solution.
Crystallized citric acid is rinsed with ice cold water.
Recrystallization is done to form larger citric acid crystals.
Highly pure, disc-shaped citric acid is the final product.
The final yield of citric acid is larger than shown due to batch processing.
Transcripts
today I am going to extract citric acid
from lemons to begin I slice up and
juice a few
[Music]
after I've just all my lemons I pour the
juice into a 1000 milliliter beaker
a 10 sodium hydroxide solution is added
to neutralize the excess acid
next I pass the solution through a
coffee filter to remove any lemon debris
after it's all filtered off I transfer
my juice to another Beaker and add
additional 10 hydroxide until I reach a
pH of nine
ph9 is indicated by the solution
shifting color to a deep Orange
at this point the citric acid from the
lemons has been converted to sodium
citrate
now I add a strong calcium chloride
solution which will convert soluble
sodium citrate to insoluble calcium
citrate
there's no way to add too much so go
crazy
next I give the calcium citrate an hour
to begin to settle out of solution
to isolate my calcium citrate I use
vacuum filtration
it was at this point I realized a vacuum
is required for vacuum filtration
much better but still slow compared to
most inorganics
I will note here that a Cold Water Rinse
of the filtered calcium citrate would
have made future steps much cleaner I
didn't do one so this is for anyone who
cares to try this discard the filtrend
you don't need it
next I transfer my filtered calcium
citrate to a fresh beaker foreign
a very dilute solution of 15 sulfuric
acid
this will react with the calcium citrate
to reform citric acid and precipitate
white calcium sulfate
calcium sulfate is also called gypsum
and can be useful
relax
I again vacuum filter this solution but
this time I will be keeping the filtered
and discarding the filtered up gypsum
foreign
solution is added to a dish and cooked
down to 10 percent of the initial volume
the resulting solution is placed in the
freezer to form citric acid crystals
last diet my crystallized citric acid to
a small filter and pull a vacuum
this has rinsed several times with ice
cold water to clean the crystals
I also did a recrystallization of crude
acid off-camera to keep the video short
unnecessary but it forms larger crystals
after scooping it out I am left with
this highly pure disco citric acid
the final yield was Far larger than this
but it was done in batches and I don't
want to force you to watch them all
as always follow for more
5.0 / 5 (0 votes)