By: Steve Bintz, Katie Jones, Tyler Babbie
Lab Report
Steve Bintz
Katie Jones
Tyler Babbie
Section 4
Team 4
Project 2: Potter’s Potions Predicament
November 7, 2005
Abstract (Experimental Summary)
The purpose of this experiment was to synthesize a small amount of magnesium
acetate for Potter’s “Confusing Concoction” through and acid-base reaction. It was
determined that the best method to remove the salt from the water, produced by the
reaction, was to heat the solution until only a solid remained. In addition, a simple anion
and cation test was done on the solution to confirm the presence of the correct materials.
Also, the effects of limiting reagents were evaluated by varying the amounts of chemicals
used. The percent errors were acceptable because the highest was 23.1%, while percent
yields were high with the lowest being 77%, suggesting the experiment was a success.
The errors came about from overheating and one major miscalculation in the proposal
stage of the lab. This calculation error caused too much product to be produced,
specifically, 3.662g, during one of the limiting reagent reactions, but nonetheless
produced a very close amount to the theoretical value. It was confirmed that the solid
which was produced was indeed magnesium acetate by proving the anion and cation
presence. It can be concluded that the experiment was a success.
Proposal
Notebook
Report
Peer review
(20)
(15)
(55)
(10)
Total
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By: Steve Bintz, Katie Jones, Tyler Babbie
I. Introduction
Harry Potter wants to get extra credit in his potions class. In order to receive the
credit, he must synthesize the primary ingredient in one of many possible potions. Team
four, who had previously made Professor Snape suspicious, was chosen to help Harry
make about two grams of magnesium acetate. This is the main ingredient in a potion
which reminds everyone who drinks it of lemonade. However, because the team has
peaked the Professor’s interest, they must also prove that the synthesis actually produces
the necessary product by performing purity tests.
An acid-base reaction is one which, when completed, produces a salt and water.
The key is whether the salt which is produced is soluble in water. If it is not, then a
precipitate will be produced, meaning what a solid will appear, but if it is, then the salt
will be suspended in the water. It is important to know which is the case before the
experiment is started in order to devise a method to extract the salt, which is the desired
substance, from the water it’s in. Here, the magnesium acetate was soluble in water,
which means the water had to be boiled off in order to obtain the product.
In this experiment, it is very important to have very precise and accurate
calculations. Examples of how to determine the experimental mass of product produced
can be found in Appendix A. Here, the exact theoretical amount of magnesium acetate
which was to be produced can be found. This number is based on the amounts of the raw
ingredients used.
II. Experimental
The experiment commenced after having determined the correct chemicals to
produce the desired magnesium acetate along with the balanced chemical equation for the
reaction. In the experiment, magnesium hydroxide and 1M acetic acid were mixed in
pre-determined ratios based on stoichiometry from the chemical equation. After mixing
the ingredients together, the liquid was divided into two evaporating dishes and covered
with watch glasses. These materials were previously massed in order to determine the
total change in mass at the end of the experiment. Next, these were placed onto hot
plates and heated until a solid had formed. It was important here to keep close watch of
how much liquid was left since it would be detrimental to burn off any product. After
making the decision that the liquid had been boiled off. The materials were cooled and
weighed. After recording the mass, they were reheated for a short time and subsequently
weighed. This was done until constant mass had been achieved within 0.005g.
To demonstrate the effects of limiting reagents, the same process was used except
different masses of starting substances were used. To show the acetic acid as the limiting
reagent, more magnesium hydroxide was used. To confirm magnesium hydroxide as the
limiting reagent, more acetic acid was placed into the solution. The key here is that, after
heating, it was demonstrated that still only the expected amount of magnesium acetate
was produced, not more.
In order to ensure that the product was in fact magnesium acetate, it had to be
determined first if the magnesium cation and acetate anion were present. To do this, two
different purity tests were used, one which tested for the presence of the cation and one
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By: Steve Bintz, Katie Jones, Tyler Babbie
for the anion. Both tests were conducted on the mixture immediately after the original
ingredients were mixed and before any heating. It was confirmed that both the necessary
cation and anion were present, which proves that magnesium acetate was produced
through this synthesis and nothing else.
III. Results and Discussion
The results of this experiment can be found in the following tables. Table 1
summarizes the results for the “perfect” synthesis, table 2 summarizes the results of
reagent #1, and table 3 summarizes the results of reagent #2. Sample calculations of this
data can be found in Appendix A.
2HC2H3O2 + Mg(OH)2  2H2O + Mg + 2C2H3O2
2H20 + Mg + 2C2H3O2 heat> 2H20 (g) + Mg(C2H3O2)2
Table 1-Perfect Synthesis= 68.3ml of 1M Acetic Acid, 0.820g Magnesium Oxide
Mass of
Mass of evaporating
Mass of evaporating Powder/Precipitate
evaporating dish
dish, watch glass, and dish, watch glass, and
Mass (g)
and watch glass (g)
solution before
powder: after
heating (g)
heating (g)
Part 1
60.08g
99.05g
61.07g
0.99g
Part 2
57.51g
88.57g
58.06g
0.55g
TOTAL:
1.54g
Table 2-Reagent #1= 68.3ml of 1M Acetic Acid, 1.500g Magnesium Oxide
Mass of
Mass of evaporating
Mass of evaporating Powder/Precipitate
evaporating dish
dish, watch glass, and dish, watch glass, and
Mass (g)
and watch glass (g)
solution before
powder: after
heating (g)
heating (g)
Part 1
56.914g
91.959g
58.571g
1.657g
Part 2
63.035g
97.982g
64.726g
1.691g
TOTAL:
3.348g
 Final precipitate mass is off due to incorrect calculations in the proposal phase of this
experiment. The incorrect calculations are shown on Appendix A, along with what was
supposed to be the correct calculations.
Part 1
Part 2
TOTAL:
Table 3-Reagent #2= 74.8ml of 1M Acetic Acid, 0.820g Magnesium Oxide
Mass of
Mass of evaporating
Mass of evaporating Powder/Precipitate
evaporating dish
dish, watch glass, and dish, watch glass, and
Mass (g)
and watch glass (g)
solution before
powder: after
heating (g)
heating (g)
56.999g
93.261g
57.940g
.941g
63.078g
100.230g
63.078
.76g
1.70g
Table 4- Percent Yield
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By: Steve Bintz, Katie Jones, Tyler Babbie
Perfect
Original Reagent # 1
Actual Reagent #1
Reagent #2
Percent Yield
77%
1.67x 10^2 %
91.42 %
85%
The method used in the experiment was an acid base reaction. For this
experiment, mixing aqueous magnesium hydroxide with acetic acid yields water and
aqueous magnesium and acetate ions. The water is removed by boiling. As the water is
removed, the magnesium and acetate ions bond to form magnesium acetate. Solving for
the limiting reagents, we found that we would need 68.3 ml 1M acetic acid and 0.82g of
magnesium hydroxide. This is the pair of reactions utilized:
2HC2H3O2 + Mg(OH)2  2H2O + Mg + 2C2H3O2
2H20 + Mg + 2C2H3O2 heat> 2H20 (g) + Mg(C2H3O2)2
The results show that the “perfect” synthesis of 2.00 grams of magnesium acetate
was indeed not perfect, but instead 1.54g, which is shown in Table 1 and is a difference
of .46g. Thus, this experiment basically consisted of heating the liquid acetic acid out of
the solution: hence, forming the powder magnesium oxide precipitate. Then, the results
from Reagent #1 were also off, but more so than the others. This is shown in Table 2
when the final experimental precipitate mass was 3.348g, which is much larger than the
intended 2.00g of magnesium acetate, by a difference of 1.35g. This difference is due
entirely to miscalculations in the beginning of this experiment when it was decided how
much of what, to use, in order to get the correct answer of acetic acid being the limiting
reagent. This is shown in the sample calculations in Appendix A when it turned out that
the magnesium oxide was the limiting reagent instead of the acetic acid, which was the
entire purpose of this part of the experiment. Furthermore, it is also shown through these
calculations that in order to get the result desired, in order to prove that the acidic acid
was the limiting reagent, 4.86 g of the solution Mg(C2H3O2)2 should have been made
originally. Basically, this means that there wasn’t enough magnesium oxide used, or less
acidic acid could’ve been used. Next, the results from Reagent #2 showed to be the most
accurate of the three various parts. This is shown in Table 3 as the final precipitate mass
is 1.70g, the closest of the three to the objective 2.00g. Although there is some error in
this part of the experiment, it still shows that the magnesium hydroxide is the limiting
reagent because the acetic acid will be in excess and the magnesium hydroxide will not
allow more to be made.
Two tests were performed to determine the purity of our magnesium acetate.
The first was using a flame test to check for magnesium. The procedure detailed in the
handout was followed. Dipping our nichrome wire into the aqueous solution of
magnesium acetate and then holding it over a flame, no change was visible. This is
characteristic of a magnesium cation. If the flame had changed, then the solution would
be assumed to have been contaminated.
The test for acetate was more involved. Following the procedure on the sheet, we
put 2ml of our solution in a test tube. 1ml of ethanol was added to the test tube, followed
by one drop of concentrated sulfuric acid. When this solution is then heated in a water
bath, it gives off a fruity smell. The scent of fruit was indeed smelled by the
experimenters as well as bystanders.
Imperfections in the experiment lead to error. When boiling the water out of the
solution, the bubbling solution occasionally dripped out of the evaporating dishes. Also,
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incomplete evaporation could lead to a heavier apparent mass of magnesium acetate than
was actually there. Human error in calculation is potentially the biggest source of error in
this project. A mistake in the calculation of the correct amount of acetic acid was a large
mistake in the lab. This mistake probably happened when in molar mass calculations.
Calcium magnesium acetate is used as an environmentally friendly alternative to
sodium chloride road salt used to de-ice roads. It is less toxic to organisms in water and
on land (McFarland). Our method synthesizes magnesium acetate, a major component of
calcium magnesium acetate. It does this using no dangerous chemicals. Using the acidbase reaction to produce magnesium acetate would be a safe way to produce alternative
road salt.
Percent yield is the actual yield divided by the theoretical yield and multiplied by
100 %. In this experiment, the percent yields are particularly important because it is an
indicator of how efficient the experiment was in each of the three different parts.
Furthermore, the results in this experiment for percent yield are shown in Table 4 and
Appendix A. The results in Table 4 show that if the calculations were again correct in the
proposal, then the reagent #1 would have the highest percent yield of 91.42%. However,
this is not the case. Hence, excluding reagent #1 because of its inaccuracy, reagent #2
was the most accurate and has the highest percent yield of 85% and the “perfect”
synthesis is close behind with a 77% yield.
IV. Conclusions
The experiment concludes that it is possible to synthesize predetermined masses
of magnesium acetate in an acid-base reaction by controlling the limiting reagents. For
example, when 0.82g Mg(OH)2 is used with our experimental procedures, there will be
about 1.5-1.8 g product. It is not possible to synthesize exactly 2g of this product using
our experiment and lab procedure. Cation and anion tests prove that our synthesized
product includes both magnesium and acetate. If this experiment were to be done again,
the procedure could be improved. More attention to the preliminary calculations would
remove much of the error in this lab. A better device to evaporate the water from the
magnesium and acetate solution would be better than the evaporation dishes with watch
glasses, or perhaps splitting the solution three ways would have reduced spilling.
V. References
McFarland, B.L.; O'Reilly, K.T., Environmental Impact and Toxicological
Characteristics of Calcium Magnesium Acetate, 1992. IN: Chemical Deicers and the
Environment. Lewis Publishers, Boca Raton, Florida. p 194-227. 9 fig, 6 tab, 50 ref.
http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=ENV&recid=9306
831&q=environmental+impact+of+magnesium+acetate&uid=786974874&setcookie=yes
[accessed: November 5, 2005]
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By: Steve Bintz, Katie Jones, Tyler Babbie
Appendix A - Sample Calculations
Katie Jones
Precipitate mass
= (1) [Evaporating dish, watch glass, and precipitate mass (g) - evaporating dish
and watch glass mass (g)]
= 58.571g-56.914g= 1.657g
= (2) [Evaporating dish, watch glass, and precipitate mass (g) - evaporating dish
and watch glass mass (g)]
= 64.726g-63.035g= 1.691g
Total = (1) [Evaporating dish, watch glass, and precipitate mass (g) - evaporating
dish and watch glass mass (g)] + (2) [Evaporating dish, watch glass, and
precipitate mass (g) - evaporating dish and watch glass mass (g)]
Total= (1) precipitate mass- (2) precipitate mass
= 1.657g + 1.691g
= 3.348g
***Due to incorrect calculations in the proposal portion of this experiment, the
rectified calculations will be provided below, along with the original to show the
mistakes made.
Original % error =│(experimental value – true value)│ x 100%
true value
=│3.348g-2.00g│ x 100% = 67.5% error
2.00
Original Limiting Reagent #1
2HC2H3O2 + Mg(OH)2  2H2O + Mg + 2C2H3O2
1M, 68.3ml
1.5g
68.3ml HC2H3O2 x 1 mol x
1 L x 1 mol Mg(C2H3O2)2 x 142.398g = 4.86g
L
1000ml
2 mol HC2H3O2
1 mol
Mg(C2H3O2)2
1.500g Mg(OH)2 x 1 mol x 1 mol Mg(C2H3O2)2 x 142.398g = 3.662g Mg(C2H3O2)2
58.326g 1 mol Mg(OH)2
1 mol
Original % Yield= Actual yield
x 100%
Theoretical yield
= 3.348g x 100% = 1.67 x 10^2 % yield
2.00g
Actual % error =│(experimental value – true value)│ x 100%
true value
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=│3.348g-3.662g│ x 100% = 8.58% error
3.3662
Actual % yield =
Actual yield
x 100%
Theoretical yield
= 3.348g x 100% = 91.42 % yield
3.662g
Steve Bintz
74.8mL HC2H3O2 │ L
│ mole │mole Mg(C2H3O2)2│58.32 g Mg(C2H3O2)2 = 2.18g
│1000mL │ L │ 2 mole HC2H3O2 │mole Mg(C2H3O2)2
.82 g Mg(OH)2 │ mole Mg(OH)2 │mole Mg(C2H3O2)2 │ 142.40 g Mg(C2H3O2)2 = 2.00g
│58.32 g Mg(OH)2 │ mole Mg(OH)2 │ mole Mg(C2H3O2)2
Percent Yield = Actual Yield x100
Theoretical Yield
Actual Yield = Weight of dish and glass after heat – weight of dish and glass before
Actual Yield = (57.940g – 56.999g) + (63.838g – 63.078g) = 1.7g
Theoretical Yield = 2.00g (as calculated above through stoichiometry)
Percent Yield = 1.7g x 100% = 85%
2.00g
Percent Error = | experimental value – true value|
True value
x 100%
Percent Error = | 1.7 – 2.00| x 100% = 15 % error
2.00
Tyler Babbie
63 ml 1M HC2H3O2 x 1L/1000ml x 1 mol Mg(C2H3O2)2 / 2 mol HC2H3O2
x 142.398g Mg(C2H3O2)2 / 1 mol Mg(C2H3O2)2 = 4.8g Mg(C2H3O2)2
0.820g Mg(OH)2 x 1 mol Mg(OH)2 / 58.3295g Mg(OH)2 x 1 mol Mg(C2H3O2)2 / 1 mol
Mg(OH)2 x 142.398g Mg(C2H3O2)2 / 1 mol Mg(C2H3O2)2 = 2.002g Mg(C2H3O2)2
Mass of evaporation dish and watchglass set 1= 60.08g
Mass of evaporation dish and watchglass set 2= 57.51g
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By: Steve Bintz, Katie Jones, Tyler Babbie
Mass of set 1 and solution= 99.05g
Mass of set 2 and solution= 88.57g
Mass of set 1 after water is boiled out= 61.07g
Mass of set 2 after water is boiled out= 58.06g
Mass after heating- mass of evaporation dish and watchglass set= mass of magnesium
acetate
61.07-60.08= 0.99g
58.06-57.51g=0.55g
Adding the masses
0.99g+0.55g= 1.54g magnesium acetate
Percent Yield = (Actual yield/Theoretical Yield) x 100
(1.54/2.002)x 100 = 76.92% yield
Percent Error = ((Experimental – Expected)/ Expected) x 100
((1.54-2.002)/2.002) x 100= -23.1% error
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