Team Members: Johnathon Cribb
Michelle Pryce
Shaina Stewart
Marlee Stokes
Kidney Stones: Their Synthesis, Destruction,
And Prevention
Introduction
The purpose of this project was to synthesize kidney stones similar to those
found in the human body due to infection. Also, after synthesis, we hoped to find
different solutions or chemicals that would possibly dissolve or prevent kidney stones
from forming in the first place.
Kidney stones form in the urinary tract when byproducts of the urine get
stuck to the inner surface of the kidney. The stones are usually formed by calcium in
combination with another chemical, either oxalate or phosphate1. Most kidney
stones can be passed out through the urinary tract without the aid of a doctor or
physician, but other more serious stones could lead to long-term effects and may
require more extensive medical attention. When stones occur in the urinary tract
(ureter), doctors refer to the condition as urolithiasis.
In lab, we had to develop five different solutions that would possibly
precipitate to form stones. Only four of the five actually produced a precipitate, so
those were the only useful ones in synthesizing our kidney stones. Once the stones
were formed, we let them dry for a week and then tested different solutions to see if
they would dissolve in them. Also, we used these solutions to see if kidney stones
would be able to form in their presents. The results can be seen in the Results section
below.
Table 3: Results from
dissolving experiments
Solvent
CaC2O4
Ca(PO4)2
CaCO3
Lemon Juice
Slightly
Yes
Yes
Celery Seed
Tea
Orange
Juice
Olive Oil
No
No
No
No
Yes
Yes
No
No
No
EDTA
No
Yes
Yes
juice, orange juice, EDTA, and HCL acid were effective at dissolving the stones
while celery seed tea and olive oil were not. As it is clear to see, the stones
synthesized from reactions 2 and 3 dissolved readily during most of the tests while
the stone synthesized from reaction 1 failed to do so. This result is explained by
noting the poor solubility of the Oxalate ion in water.
In addition to running tests on how to dissolve the stones, tests were also
carried out to investigate how to inhibit stone formation. The results from these
tests can be seen in table 4. For the acids, the results that were achieved were
expected. Since acids disassociate into H+ and a negatively charged ion, they
prevent the stone formation from occurring by preventing the anions and cations of
the insoluble salts from coming into contact with each other. The results obtained
from celery seed tea and EDTA were unexpected. The EDTA should have behaved
in a similar manner as the acids did, since it is a chelating agent. The results
obtained from celery seed tea are currently inexplicable.
1 M HCl
Yes
Yes
Yes
Conclusions
6 M HCl
Yes
Yes
Yes
Solvent
CaC2O4
Ca(PO4)2
CaCO3
Lemon Juice
No
No
Yes
Celery Seed
Tea
Orange
Juice
Olive Oil
Yes
Yes
Yes
Yes
No
Yes
It was concluded that kidney stones synthesized from calcium oxalate made
the best kidney stones based on physical properties, chemical properties, and actual
yield as compared to theoretical yield. In order to dissolve the stones, several
methods were tried. 6M HCl and 1M HCl were used successfully to dissolve each
type of kidney stone. EDTA was used to successfully dissolve the stones synthesized
from calcium oxalate and calcium phosphate. The remaining dissolving agents,
lemon juice, celery seed tea, and orange juice only had limited success in dissolving
the synthesized stones.
Lemon juice was judged to be the most promising, safest agent that could be
ingested in order to dissolve kidney stones. However, with its limited effectiveness,
the best method would be prevention of formation of stones. One could do this by
limiting soda consumption (contains carbonate that is used to form solid stones),
coffee, tea, and increasing consumption of citric fruits (could work like HCl in
dissolving or preventing stone formation).
No
No
No
EDTA
No
No
No
1 M HCl
Yes
Yes
Yes
Results
Table 4: Results from
prevention tests
Table 1: Initial Reactions
(each row represents one
reaction)
Reactant 1 + Reactant 2
→
Product 1 + Product 2
Reaction 1
Na2C2O4
CaCl2
2NaCl
CaC2O4
Reaction 2
3Ca(NO3)2
2NaH2PO4
2NaH2(NO3)2
Ca3 (PO4)2
Reaction 3
Ca(NO3)2
Na2CO3
2Na(NO3)
CaCO3
Reaction 4
2Na3PO4
3MgCl2
6NaCl
Mg3(PO4)2
Equation 1:
Stiochiometry
Mprecipitate / MWprecipitate = Molsprecipitate
_
Discussion
Molsreactant = (Molsproduct * Coefficientreactant)
Coefficientproduct
Mreactant = Molsreactant * MWreactant
Table 2: Percent Yield of
Reactions
Precipitate
Percent Yield
CaC2O4
92%
Ca(PO4)2
7%
CaCO3
74%
During the initial planning phases, it was decided that four stone forming
reactions would be analyzed. These reactions can be found in table 1. Going in
order of appearance, these reactions produce the following precipitates CaC2O4 ,
Ca3(PO4 )2 , CaCO3 , and Mg3(PO4)2. After performing small scale tests, it was
determined that the fourth reaction was not viable for purposes of this investigation
as it yielded a very small amount of precipitate.
Reactions, 1,2, and 3 were then synthesized. Equation 1 was utilized in
determining the exact amount of reactants needed to synthesize 2.5 g of stone
product. During synthesis, several differences arose between the three reactions.
The most noticeable difference was see in their percent yields. As seen in table 2,
reaction 1 had a percent yield of 92%, reaction 2 had a percent yield of 7%, and
reaction 3 had a percent yield of 74%. The high percent yields of reaction 1 and 3
were expected, since reactions involving two insoluble ions normally go to
completion. The reason for reaction 2’s low percent yield is not understood. The
reaction was synthesized twice, and the second synthesis yielded similar results.
This makes contamination a highly unlikely cause for these results.
After a significant amount of stone was synthesized, the three types of stone
were then subjected to various solvents in an attempt to dissolve them. The results
results from this series of tests can be seen in table 3, and table 4. Table 3 shows the
results from small scale tests carried out in a reaction well. These tests only involved
approximately 0.1 g of synthesized stone; however, they showed that only lemon
References
1. http://www.webmd.com/kidney-stones/kidney-stones-adults (accessed March
2007)