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Performance Task:
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Pearly came home from the drug store one day with a new prescription. She opened her bottle that night and noticed a small package inside that said, "Desiccant - Do not eat." The next day, Pearly bought a new stereo. When she opened the box, she found a similar package to the one she found the night before. She could not help but wonder about the importance of these desiccant packs. This task will help you understand the purpose and importance of desiccant packs.
Materials Needed:
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test tube holder
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weighing paper
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copper (II) sulfate
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goggles
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distilled water
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desiccator
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Bunsen burner
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watch glass
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test tube
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graduate cylinder
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Weigh an empty test tube. Weigh and place 2 grams of copper (II) sulfate into the weighed test tube. Note the color of the copper (II) sulfate compound. Record the weight of the copper (II) sulfate in the table below under the heading "First weighing."
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Heat the copper (II) sulfate compound slowly until it all turns white and then cool in a
desiccator.
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When the compound is cool, determine its weight and record in the table under the heading "Second weighing."
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Subtract the second mass from the first mass to obtain the grams of water in the original sample and find the percent of water.
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Place the cooled copper sulfate solution in a watch glass. Slowly add water until it returns to its original blue color.
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Does the volume of water added to the heated and cooled copper sulfate equal the difference of the mass between the two
weighings?
Optional
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Research the techniques of dehydration of products other than the use of desiccants.
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Construct a poster exhibiting the products of dehydration.
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Write an essay on the principle of dehydration for the preserving of foods.
Note to the teacher: Students should work in pairs on this task. After this task, students should understand why keeping moisture away from drugs is important to the pharmaceutical industry. He/she will understand that desiccants are chemicals used to absorb water from the atmosphere and hydrates are chemicals that have water attached to them.
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Knowledge / Skills:
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Know and apply the principles of scientific inquiry. (xs1)
Measure properties of the environment using dimensional quantities such as time, length, mass, pressure, volume, acceleration, etc. Compare quantities and consider the error involved with measuring environmental properties. (s23)
Understand physical/chemical change (e.g., change of phase between gases, liquids, and solids). (s57)
Perform operations with signed (positive and negative) numbers, including decimals, ratios, percents, and fractions. (m1)
Gather information from a variety of sources, including electronic sources, and summarize, analyze, and evaluate its use for a report. (ela3)
Use expository writing skills in subjects other than English language arts. (ela58)
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Rubric:
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(Material in parentheses refers to the optional part of the task.)
3 Points = The student is able to weigh the material and use proper techniques when heating a test tube. He/she is able to calculate the percent of water in the original sample accurately. His/her work shows understanding of the concepts in this task. (The quality of the research, written essay and poster demonstrates good understanding of the concepts and effort.)
2 Points = The student has difficulty with finding the percent of water, but is successful with some coaching. His/her work shows evidence of understanding of the concepts in this task. (The quality of the research, written essay and poster demonstrate adequate understanding of the concepts and effort.)
1 Point = The student does not complete the assignment. The data table is not complete and the percent of water is not determined. His/her work shows limited understanding of the concepts in this task. (The research, written essay and poster show lack of effort and demonstrate little understanding of major concepts in the task.)
0 Points = The student does not complete the task and shows little, if any, understanding of the concepts in the task. (No meaningful research, written essay or poster is attempted.)
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