Grades 9-12 Performance Task
Contributed by: New York State Education Department (NYSED)
Developed through University of Buffalo and NORC (1991)
Part A
Introduction:
This laboratory test presents a problem. Your task
in Part A is to plan and design an experiment to solve the problem.
You will have 30 minutes to complete Part A. At the end
of the 30 minutes, your answer sheet will be collected. You will
then receive separate directions for Part B. In Part B you will
use materials and equipment provided in the laboratory kit to
collect experimental data for this problem. You may wish to do
your preliminary planning on the sheet labelled "Working
Copy." Write this plan on the appropriate answer sheet in
your test booklet.
Problem:
A hydrated salt is a solid substance with water
molecules at some of the lattice points in the crystal. The formula
of a hydrated salt is written in a form that includes the number
of water molecules associated with it. This water can be driven
out of the crystal by heating. Your task is to design an experiment,
using the materials (and/or others) listed below, which will determine
an empirical formula for a hydrated salt X. Be sure to tell how
you know when all the water has been removed from the hydrate
crystals.
a) Under the heading PROCEDURE list in order the
steps of the procedure you will use to solve the problem. You
may include a diagram to help illustrate your plans for the experiment.
Include any safety procedures you would follow.
b) Construct a DATA TABLE or indicate any other
method that you could use to record the observations and results
that will be obtained.
PLEASE NOTE: In Part A you are NOT to proceed with
any part of the actual experiment. You are just to plan and organize
a way to investigate the problem.
Materials:
- 1 crucible with cover
- 1 pair of crucible tongs
- 1 porcelain triangle
- 1 tripod
- balance
- bunsen burner with matches
- heat resistant tile
- hydrated sample X
- access to a periodic table
- safety goggles
- calculator
ANSWER SHEET
PART A - Experiment Design
Organize your experiment design under the following
headings:
PROCEDURE and DATA TABLE.
Use the front and back of these sheets if necessary.
PROCEDURE (Include diagram if appropriate)
DATA TABLE (For results and observations)
Hydrated Salt - PART B
Determination of the formula of a hydrated salt
You will have 50 minutes to complete this part.
You have been provided with a detailed Procedure (see next page)
which you are to follow. Record your work for Part B on the answer
sheet under the appropriate headings.
a) Perform the experiment by following the steps outlined
in the procedure.
b) Under the heading RESULTS/OBSERVATIONS record the
results of the experiment. Use statements, descriptive paragraphs,
and tables of data where appropriate.
c) Under the heading CALCULATIONS show all equations
and calculations used.
d) Under the heading CONCLUSION give an interpretation
of your results. What did you learn from the experiment?
e) You have also been provided with a sheet labelled
"Working Copy." Use this scrap sheet for any initial calculations
or conclusion. However, be sure to enter your final work on the
appropriate answer sheets.
f) At the end of the 50 minutes, your answer sheets
will be collected.
Materials:
- 1 crucible with cover
- 1 pair of crucible tongs
- 1 porcelain triangle
- 1 tripod
- balance
- bunsen burner with matches
- heat resistant tile
- hydrated sample X
- access to a periodic table
- safety goggles
- calculator

Procedure:
- Determine the mass of a clean dry crucible and cover. Record
the data in the data table.
- Place about 4 grams of sample X in the crucible.
-
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- Weigh the crucible, lid and hydrated sample. Record this data
in the data table.
- Set up the apparatus as shown in the diagram on the previous
page.
- Heat te crucible gently at first and then more strongly. Continue
heating for about 5 minutes, and no more than 8 minutes.
- Stop heating and weigh the crucible, lid and solid left. Record
the data in the data table.
- Given your data, determine the empirical formula of hydrated
salt X, of the form: X * ________ H20
Safety:
The hydrate crystals pose no acute toxicity
or corrosivity hazard. However:
(1) Safety goggles must be worn at all times.
(2) Hot objects must be handled with tongs
at all times.
(3) Should skin contact occur, flush thoroughly
with water.
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EXPERIMENT REPORT #5 - Part B
Record your Calculations and Conclusions on these
sheets.
RESULTS/OBSERVATIONS
CALCULATIONS
CONCLUSION
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