Percent Yield
Instructions: Complete all sections of this report and answer all questions in complete sentences
for full credit.
Title:
Objective(s):
Hypothesis: None
Materials: What scientific equipment and tools were used to collect data in the simulation?
(Record the materials as you work through the simulation.)
Materials
lots
Variables: Remember the three variables: controlled (what is kept the same), independent (what
is tested or changed), and dependent (what is the outcome or observed). List variables below as
you work through the simulation.
Type
Variables
Controlled
Time to heat; Mass of crucible and lid
Independent
Amount of magnesium
Dependent
Mass of magnesium oxide
Procedure: Clear steps are in the simulation. No written procedure is needed for this virtual
experience. However, it is important that you understand the experimental design of this lab for
the conclusion section.
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trademark of Florida Virtual School.
Data
Type the data in the data table below. Don't forget to record measurements with the correct
number of significant figures and units.
Data
Mass of empty crucible with lid
Length of ribbon cut
Mass of Mg metal, crucible, and lid
Mass of MgO, crucible, and lid
Trial 1
26.679 g
2 in
26.996 g
27.192 g
Trial 2
26.688 g
2 in
26.982 g
27.112 g
Calculations
Show your calculations for each of the following. Remember, calculations should follow rules
for significant figures.
Remember to use the balanced chemical reaction: 2Mg(s) + O2(g) → 2MgO(s).
1. Subtract the mass of the crucible and lid (row 1 in the chart) from the total mass of Mg,
crucible, and lid (row 2 in the chart) to find the mass of magnesium for each trial.
 Trial 1: 26.996 - 26.687 = 0.309
 Trial 2: 26.982 - 26.688 = 0.294
2. Subtract the mass of the crucible and lid (row 1 in the chart) from the total mass of MgO,
crucible, and lid (row 3 in the chart) to find the mass of magnesium oxide for each trial. This
is the actual yield of magnesium oxide for each trial.
 Trial 1: 27.192 - 26.687 = 0.505
 Trial 2: 27.112 - 26.688 = 0.424
3. Magnesium is the limiting reactant in this experiment. Calculate the theoretical yield of
MgO for each trial using stoichiometry.
 Trial 1: 0.512 g MgO
 Trial 2: 0.488g MgO
4. Determine the percent yield of MgO for your experiment for each trial.
 Trial 1: 86.9%
 Trial 2: 92.8%
5. Determine the average percent yield of MgO for the two trials.
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trademark of Florida Virtual School.
Conclusion
Using complete sentences, write a conclusion that addresses the following:



The purpose of the lab, what you explored, what you learned
An explanation of how percent yield can be affected during experimentation
A description of the sources of errors that impacted your data measurements
This lab was to determine the precent yield of magnesium oxide with a specific mass of magnesium. The
product, MgO, has a higher mass than the reactant, Mg, because oxygen was added. This demonstrates
conservation of mass because mass is not created or destroyed in chemical reactions, but the mass of
both reactants was not measured before the reaction. Percent yield can be affected by the amount of
each reactant and experimental conditions. Sources of error that could impact the data are incorrect
measurements, impurities in the reactants and the combustion reaction not going to completion. I could
further investigate this by trying with a different amount of magnesium or heating the reaction multiple
times.
Post-Lab Connection Questions
Answer questions in complete sentences.
1. In physical labs, when conducting this experiment, sometimes the metal is heated and
cooled for several rounds. After each round, the mass is recorded. This continues until the
mass measurements remain the same. Explain the purpose of this process and how it
might reduce errors.
The purpose of doing this with an is because it will help reduce the errors during the
experiment, so then the metal will be in its pure state so that when the data is recorded it
will be accurate. Once the metal reaches a state of no change, scientists will know that the
data is done
2. Imagine a company producing MgO with the same cost of materials as in this lab. The
company averages a 92 percent yield for MgO. Would you recommend the company to
continue their process or update? Support your recommendation using your calculations
and understanding of stoichiometry from this lab.
Yes I would recommend, but I would suggest that they try to slightly raise the yield
closer to the theoretical yield.Calculations: 0.92*13.12=12.06 grams of MgO
Unless Otherwise Noted All Content © 2022 Florida Virtual School. FlexPoint Education Cloud™ is a
trademark of Florida Virtual School.
Unless Otherwise Noted All Content © 2022 Florida Virtual School. FlexPoint Education Cloud™ is a
trademark of Florida Virtual School.