Course: Chemistry
Grade Level: 10-12
Type: Informational/Explanatory
Structure: Synthesis
Teaching Task 18: After researching informational texts, writing a background/information
section and developing a hypothesis, conduct an experiment on the selected topic. Upon
completion of the experiment, write a formal lab report that explains the results and confirms or
rejects the hypothesis. What conclusion or implications can you draw? Cite at least 2 sources,
pointing out key elements from each source. A bibliography in APA format is required.
Performance Level: Approaches Expectations
Purpose: The purpose of the lab was to observe reactions between ionic solutions, predict
products that form a precipitate and to write the double replacement reactions which occur.
Background Information:
A chemical reaction is a process that leads to the transformation of one set of chemical
substances to another. An chemical equation is the symbolic representation of a chemical
reaction where the reactant entities are given on the left hand side and the product entities on
the right hand side. The Law of Conservation of Mass is a chemical changes. Which means that
the total mass of all of the reactants in the chemical reaction is equal to the total mass
of products in the chemical reaction. A double-displacement reactions describe reactions in
which two or more new products are formed from two molecular reactants. On the other hand
in a double-displacement reactions, reactants exchange ions or elements to form products.
Precipitate is the formation of a solid in a solution or inside another solid during a chemical
reaction. When doing precipitate a good chart is a solubility. The reason why is a solubility
chart refers to a chart with a list of ions and how, when mixed with other ions, they can become
precipitates.
Hypotheses:
6. If Sodium Carbonate is reacted with Barium Chloride, then Sodium Chloride will form a
precipitate and aqueous Barium Carbonate will be produced because it is a double replacement
reaction and the Sodium and Barium ions trade places.
7. No Reaction
8. If Sodium Carbonate is reacted with Calcium Nitrate, then Sodium Nitrate will form a
precipitate and aqueous Calcium Carbonate will be produced because it is a double
replacement reaction and the Sodium and Calcium ions trade places.
10. If Barium Chloride is reacted with Ammonium Sulfate, then Barium Sulfate will form a
precipitate and aqueous Ammonium Chloride will be produced because it is a double
replacement reaction and the Barium and Ammonium ions trade places.
12. If Barium Chloride is reacted with Potassium Phosphate, then Barium Phosphate
will form a precipitate and aqueous Potassium Chloride will be produced because it is a double
replacement reaction and the Barium and Potassium ions trade places.
15. If Calcium Nitrate is reacted with Potassium Phosphate, then Calcium Phosphate will form
a precipitate and aqueous Potassium Nitrate will be produced because it is a double
replacement reaction and the Calcium and Potassium ions trade places.
Procedure:
1.Combine 5 drops of each solution in a test plate well
2. If a solid forms at the bottom or the solution turns cloudy, record that s precipitate forms on
the data table
3. Continue until all combinations are completed
4. when finished, thoroughly clean the test plates, and return them and the dropper bottles to
the proper place.
Materials:
● test plate
● Sodium Carbonate
● Barium Chloride
● Calcium Nitrate
● Ammonium Sulfate
● Potassium Phosphate
Results:
Data Table 1- Reactants, predicted products and predicted precipitates.
Reactants
Predicted
Products
Predicted
Precipitate
6
Na2CO3
BaCI2
NaCI
Ba2CO3
Ba2CO3
7
Na2CO3
(NH4)2SO4
NR
8
Na2CO3
Ca(NO3)2
Na2SO4
(NH4)2CO
3
Na2NO3
CaCO3
10
BaCI2
(NH4)2SO4
BaSO4
NH4CI
BaSO4
12
BaCI2
K3PO4
Ba(PO4)2
KCI
Ba(PO4)2
15
Ca(NO3)2
Ca(PO4)2
Ca(PO4)2
Reaction #
CaCO3
K3PO4
KNO3
Discussion/Conclusion
The purpose of the lab was to observe reactions between ionic solutions, predict products
that form a precipitate and to write the double replacement reactions which occur.
Accept 6. If Sodium Carbonate is reacted with Barium Chloride, then Sodium Chloride will
form a precipitate and aqueous Barium Carbonate will be produced because it is a double
replacement reaction and the Sodium and Barium ions trade places.
Reject 7. No Reaction
Accept 8. If Sodium Carbonate is reacted with Calcium Nitrate, then Sodium Nitrate
will form a precipitate and aqueous Calcium Carbonate will be produced because it is a double
replacement reaction and the Sodium and Calcium ions trade places.
Accept 10. If Barium Chloride is reacted with Ammonium Sulfate, then Barium Sulfate
will form a precipitate and aqueous Ammonium Chloride will be produced because it is a
double replacement reaction and the Barium and Ammonium ions trade places.
Accept 12. If Barium Chloride is reacted with Potassium Phosphate, then Barium Phosphate
will form a precipitate and aqueous Potassium Chloride will be produced because it is a
double replacement reaction and the Barium and Potassium ions trade places.
Accept 15. If Calcium Nitrate is reacted with Potassium Phosphate, then Calcium Phosphate
will form a precipitate and aqueous Potassium Nitrate will be produced because it is a double
replacement reaction and the Calcium and Potassium ions trade places.
Some error could be human errors. Also if the test tubes are wet could have some thing to do
with the reaction
Annotation
Focus
2 Reading/Research 1.5 Controlling Idea
1.5 Development
2
Organization
2
This lab report addresses some aspects of the prompt by developing
the hypotheses, predicting the products, forming a limited
discussion, and conclusion which does not include balanced
chemical reactions. The writer presents background research and information
pertaining to all parts of the prompt but does not reference sources
used in the development of the background information which
would help the student to avoid plagiarism: An chemical equation
is the symbolic representation of a chemical reaction where the
reactant entities are given on the left hand side and the product
entities on the right hand side. The background information
contains inaccuracies, such as the use of molecular instead of ionic,
and the incorrect definition of the foundational Law of
Conservation of Mass.
The purpose and explanations found throughout the laboratory
report are incomplete. The report lacks any reference to the
solubility chart or written equations: The purpose of the lab was to
observe reactions between ionic solutions, predict products that
form a precipitate and to write the double replacement reactions
which occur.
The writer predicts products for double replacement reactions that
are sometimes inaccurate or incomplete: If Sodium Carbonate is
reacted with Barium Chloride, then Sodium Chloride will form a
precipitate and aqueous Barium Carbonate will be produced
because it is a double replacement reaction and the Sodium and
Barium ions trade places. The writer does not provide any
balanced chemical equations. A statement about the chemical
reactions that accepts or rejects the writer’s hypotheses is not
supported by the solubility chart and is sometimes inaccurate or
incomplete: Accept 6. If Sodium Carbonate is reacted with Barium
Chloride, then Sodium Chloride will form a precipitate and
aqueous Barium Carbonate will be produced because it is a double
replacement reaction and the Sodium and Barium ions trade
places.
The laboratory report maintains an organizational structure.
However, the report is limited due to the omission of a section
which should include balanced chemical equations. The use of
sub-headings in the discussion/conclusion section would strengthen
the organizational structure.
Conventions
2
The writer demonstrates an uneven command of the English
language and scientific vocabulary: When doing precipitate a good
chart is a solubility. The reason why is a solubility chart refers to a
chart with a list of ions and how, when mixed with other ions, they
can become precipitates. Appropriate citations and a bibliography
are needed.
Content
Understanding
2
The writer demonstrates a limited understanding of the chemistry
concepts and structure of a formal laboratory report. Some of the
products in the data table are incorrect. For example, “Ba2CO3”
should be BaCO3. Without the inclusion of chemical equations in
the laboratory report, the writer was unable to demonstrate
sufficient disciplinary content development in the discussion/
conclusion section of the report.
This student would benefit from feedback, discussion, and/or instruction in the following
areas:
•
•
•
•
•
Using a solubility chart in the purpose and throughout the laboratory report is a critical
component to this experiential activity
Inclusion of a bibliography and parenthetical citations are required
More practice in writing/balancing chemical equations and drawing conclusion based on
data that demonstrate an understanding of precipitate reactions
Using a solubility chart to write and balance chemical equations
Effective organization and development of a lab report