Group 16
Solubility Lab
Intro
What is a myth? A myth is something that is believed to be true but has not been proven true.
Mythbusters is a TV show that does experiments to prove whether or not a myth is accurate. The show
goes through a lot of different myths and they do a lot of crazy stunts to prove whether the myth is true.
Most of the things they do you shouldn’t try at home. The point is, what they do is not so different than
what is occurring in the lab. Tests are being done to prove whether or not the solutions are soluble. So
what myth busters are doing is related to what is happening in the lab. Some terms that are important
to know are solubility and also ppt, which stands for precipitate. Solubility stands for whether or not the
substance can dissolve in water and precipitate is the visible solid formed in a solution when a product
becomes insoluble. In the lab a table is created and then the observations are recorded. The goal is to
determine the unknown compounds based off of the observations on the tests for the known
compounds. Also, the solubility chart on the period table should be identical to the tests that are going
to be performed in the lab. If the tests for solubility are observed, then the information on the solubility
chart will be replicated.
Materials and Methods
The first thing that occurred was silver nitrate, iron(III) nitrate, copper(II) nitrate, lead(II) nitrate,
nickel(II) nitrate, and zinc(II) nitrate color was recorded. Then one drop of sulfuric acid was added to
each of them and the observations were recorded. One drop of sodium hydroxide was added also to the
metal nitrates and the observations were recorded. Another five drops of sodium hydroxide were added
and the results were recorded. One drop of ammonium hydroxide was added to all the metal nitrates
and then another five drops where added and the results where then recorded. The unknown
substances then went through the same test and the observations were recorded. They were then
compared to the metals nitrates that where tested before and the unknown substances where
determined.
Results
Solubility Chart Lab Table
metal nitrate
color*
H2SO4
NaOH 1d
NaOH 5d
NH4OH 5d
no change
NH4OH 1d
no ppt, clear blue
liquid
Cu(NO3)2
blue
no ppt, clear liquid
no ppt, clear blue liquid
Pb(NO3)2
colorless
white ppt, white liquid
white ppt, clear liquid
ppt dissapeared
white ppt, clear liquid
Fe(NO3)3
yellow
no ppt, clear liquid
no change
yellow ppt, clear liquid
no change
yellow ppt, clear liquid
no change
Ni(NO3)2
green
Zn(NO3)2
colorless
no ppt, clear liquid
no ppt, clear liquid
no change
no ppt, clear liquid
no change
no ppt, clear liquid
white ppt, clear liquid
ppt dissapeared
white ppt, clear liquid
AgNO3
no change
colorless
no ppt, clear liquid
brown ppt, clear liquid
no change
no ppt, clear liquid
no change
Unknown A
green
no ppt, clear liquid
no ppt, clear liquid
no change
no ppt, clear liquid
no change
Unknown B
colorless
white ppt, clear liquid
white ppt, clear liquid
ppt dissapeared
white ppt, clear liquid
no change
no change
*all of the metal nitrates in this lab are clear
Conclusion
For the lead (II) nitrate, two kinds of precipitates formed. Lead (II) sulfate and lead (II) hydroxide.
They can be represented as products in these following chemical equations.
Pb(NO3)2 + H2SO4  2HNO3 + Pb2SO4
Pb(NO3)2 + 2NaOH  2NaNO3 + Pb(OH)2
By the solubility chart, nitric acid and sodium nitrate are both soluble. The other reactant in each
equation is not; therefore a visible precipitate is formed.
For the copper (II) nitrate, one type of precipitate should have been formed when combining it
with sodium hydroxide and ammonium hydroxide, but no precipitate was observed. The chemical
reaction shows an insoluble product, shown here
Cu(NO3)2 + 2NaOH g 2NaNO3 + Cu(OH)2
By the solubility chart Cu(OH)2, copper (II) hydroxide is indeed soluble.
For the nickel (II) nitrate, no precipitates formed. Therefore, no chemical equations could be
shown to prove that they did form.
For the iron (III) nitrate, one type of precipitate formed when it reacted with ammonium
hydroxide and sodium hydroxide. The product can be represented below.
Fe(NO3)3 +3NaOH  3NaNO3 + Fe(OH)3
By the solubility chart, the product sodium nitrate is soluble as iron (III) hydroxide isn’t. Iron (III)
hydroxide is the product that forms the precipitate.
For zinc (II) nitrate, one type of precipitate formed when it reacted with sodium hydroxide and
ammonium hydroxide. The chemical equation representing the reaction is seen below.
Zn(NO3)2 + NaOH g NaNO3 + Zn(OH)2
By the solubility chart, sodium nitrate is soluble while zinc (II) hydroxide is not, therefore zinc (II)
hydroxide forms a visible precipitate.
For silver nitrate, one type of precipitate formed when it was mixed with sodium hydroxide and
ammonium hydroxide. The chemical reaction is represented below.
AgNO3 + NaOH g NaNO3 + AgOH
By the solubility chart, sodium nitrate is soluble as silver hydroxide is not. It can be said that silver
hydroxide forms a visible precipitate.
This net equation represents the reactants and products of a chemical reaction that took place
in the lab, more specifically, the one where sulfuric acid and lead (II) nitrate reacted to form two
products, one soluble and one insoluble. The soluble product, nitric acid, cannot be seen in the clear
liquid, but the insoluble product, lead (II) sulfate, can be seen as a white precipitate. This precipitate is
formed when lead combines with sulfate in the reaction. The new compound becomes insoluble and
visible in the liquid.
H2SO4 + Pb(NO3)2
4
2H+ + SO4-2 + Pb+2 + NO3Pb+2 + SO4-2
4
+2 HNO3
4
+ 2H+ + 2H++ NO3-
Balanced Equation
Aqueous solutions are broken down
Spectator ions are taken out
Unknown A was found to be nickel (II) nitrate as unknown B was found to be lead (II) nitrate.
Based on the observations in the lab, it’s only logical that this is true. Since only lead (II) nitrate and
unknown B formed a precipitate when reacted with H2SO4, they were in fact the same solution. Also,
since both nickel (II) nitrate and unknown A formed a precipitate with none of the solutions, they are
the same metal nitrate as well.
Referring back to the hypothesis, the solubility chart was not fully replicated. Some of the
precipitates could have had slower reaction rates, so before the precipitate could be formed, the
reactants were dumped down the drain. Other than a few of those mistakes, the solubility chart was
replicated.
Myths remain myths until they’re tested. If something such as a formula or postulate becomes
true before it’s tested, the formula may not work for every situation. The same is true for the solubility
chart. If it’s assumed to be true, then everyone using it could be confused or frustrated because their
reference source isn’t true. Testing a new vaccine should also be tested. Think of the catastrophe if a
vaccine that had deadly side effects was released to the public. Once again, testing something to be true
is a significant step that allows to make it true.