TITLE: Molarity
TASK DEVELOPER: Jane Silverstein
GRADE AND CONTENT AREA: Chemistry 11th
SCOPE AND SEQUENCE: Chapter 4, sect 1
TARGET TEACHING DATE: Jan 16,2007
SCHOOL: John F. Kennedy High School

STANDARDS:

CHEMISTRY - GRADES 9-12

STANDARD 5.6 CHEMISTRY: All students will gain an understanding of the structure and behavior of matter.

Strand B. Chemical Reactions: Building upon knowledge and skills gained in preceding grades, by the end of Grade 12, students will:

1. Explain that the rate of reactions among atoms and molecules depends on how often they encounter one another and that the rate is affected by nature of reactants, concentration, pressure, temperature, and the presence of a catalyst.

MATHEMATICAL APPLICATIONS

STANDARD 5.3 MATHEMATICAL APPLICATIONS: All students will integrate mathematics as a tool for problem-solving in science, and as a means of expressing and/or modeling scientific theories.

Strand B. Geometry and Measurement: Building upon knowledge and skills gained in preceding grades, by the end of Grade 12, students will:

1. When performing mathematical operations with measured quantities, express answers to reflect the degree of precision and accuracy of the input data.

Strand C. Patterns and Algebra: Building upon knowledge and skills gained in preceding grades, by the end of Grade 12, students will:

1. Apply mathematical models that describe physical phenomena to predict real world events.

PERFORMANCES:

In the classroom setting, the students will solve problems involving:

  1. Making solutions of given molarity from specific numbers of grams, or moles.
  2. Making solutions of specific Molarity using defined sizes of glassware
  3. Calculating Molarity from moles, grams, and volumes
  4. Mixing solutions or diluting solutions to achieve specific molarities
  5. Calculating numbers of moles in defined volumes of solutions of specific molarities

In a laboratory setting, the students will make solutions of specific Molarities given either mass, desired volume, and/or number of moles.  Students will use their solutions to titrate solutions of unknown Molarity.

SETTING:

Real World Setting: Laboratory applications

You are a laboratory technician. You are given a solution of unknown concentration. You must analyze the material, using a solution of known concentration.. Once you have completed your analysis, you will report your results to the other technicians employed by the lab. They will review your results for accuracy.

SMARTSKILLS:

Level I: Acquiring Data - Data students will acquire in this standards-based task: Formulas for finding concentration, relationship between molarity and number of particles in a given volume of solution.

Skills: Calculate Molarity from any set of given information. Mix solutions of any Molarity from any given set of data and size of glassware
Concepts: Number of particles distributed throughout a defined volume is proportional to the volume

Solving problems: Students will be able to calculate, mix and use solutions of known Molarity.

Level II : Applying concepts - Students will make and use solutions of calculated Molarity to analyze other solutions.

PREFERENCES:

Student Involvement - The students will complete the tasks in a whole class setting -- discuss the definition of Molarity, how to deal with molarities of mixtures, and individually solve problems at end of chapter. As a cooperative group they will assist in making solutions of desired Molarity and solve problems on worksheet. 

Instruction - Activities will be organized and delivered:

  • by differentiating the activities or strategies to offer appropriate ways for students to learn as a teacher-facilitated set of hands-on activities
  • by a student or teacher demonstration
  • by completion of a problem set on a worksheet

Use of Resources - The school will provide

  • laboratory equipment
  • textbooks, worksheets

Use of Resources - The students will provide classroom materials such as pencils, paper, notebooks

Customer for Student Work - The student will present their work as evidence of task completion to peers and to the teacher.  The test for accuracy of work will be to use the solutions made in experimental investigations and calculations.

Assessment of Student Work - The following people will be involved in assessing student work generated to complete the task:

  • The student's teacher
  • Peers

Assessment of Student Work - The following forms of assessment will be used to determine progress and results:

  • Performance assessment, correctly solving problems, explaining method of solving problem to class. Solutions made will be accurate and useful. Errors will be minimized.

Reporting Results - The assessment results will be reported as a score point on a rubric

Timeline - The estimated time needed to plan, teach, and score this task is 5 days of group work.

ACTIVITIES:

Chemistry Lab

PLANNING PHASE
Estimated Time: 1 hour

  1. Review and align instructional assignment with standards, performances, and smart skills
  2. Develop student assignments for the chemistry  lab that support the concept being taught. Prepare materials for students to use in making solutions.
  3. Provide an overview to students about expectations, activities, and assignments.  Provide prelab assignment.

IN THE CHEMISTRY LAB

Activity One: Make solution of given Molarity
Estimated Time: 30 minutes

  • Step 1: Given desired concentration and volume, calculate amount of solute needed.
  • Step 2: Weigh solute
  • Step 3: Make solution using solute and distilled water.

Expected student performance or product:  Solution will be made to specifications.
Scoring Tool: Calculations 10 points, Solution:   10 points

Activity Two:  Make Solution by dilution of another solution
Estimated Time:  30 min

  • Step 1: Given a more concentrated solution, student will calculate necessary glassware and necessary volume to create desired solution. Student will measure and dilute the concentrated solution.

    Expected student performance or product:  There will be a solution, accurately made, of the desired Molarity.
    Scoring Tool:  See Activity three.

Activity Three:
Estimated Time: 30 minutes

  • Step 1: Students will titrate their solutions from Activity two against solutions of known Molarity.
  • Step 2:Students will calculate the Molarity of the solutions that they made from the experimental data.
  • Step 3: Students will calculate the percent error in the Molarity of their solutions.
    Expected student performance or product: Error should be less than 10%


    Activity Four:    Estimated time: 30 minutes

  • Students will write a report of their laboratory activity.  The report will include: Purpose, Procedure, Results, Data Analysis, Conclusion


RETURNING TO THE CLASSROOM
Estimated Time:

  • Discuss sources of error, in process and in performance, as written in the conclusion to the lab report..
  • Design another investigation that might minimize errors.
BENCHMARKING:

Student Performance One: 1.  Student will be able to calculate Molarity from any set of given information. Assessments will be given as a quiz.

Student Performance Two: Student will accurately make a solution of given Molarity.

Assessment Benchmarking Example:  Solution will accurately react with a solution of known concentration.

SCORING:

John F. Kennedy High School Science Rubric: Laboratory Activity

Level 4

There is evidence in this response that the student has a full and complete understanding of the question or problem.

  • All calculations are done correctly.
  • The accuracy of the analysis is within 7.5 % error or less
  • Laboratory Report is written according to protocol, all sections are complete.
  • The conclusion answers the purpose and reflects a complete synthesis of information gathered in the investigation.

Level 3

There is evidence in this response that the student has a good understanding of the question or problem.

  • Calculations contain only one error.
  • Analysis is accurate to within a 10% error.
  • Laboratory report is almost complete, with only minor omissions.
  • The conclusion reflects some synthesis of information and is not merely a duplication of the purpose.

Level 2

There is evidence in this response that the student has a basic understanding of the question or problem.

  • Calculations contain several errors.
  • Analysis is accurate to within 15% error.
  • Two or three sections of the Laboratory report are incomplete.
  • The conclusion provides little or no synthesis of information and is merely a repeat of the purpose.

Level 1

There is evidence in this response that the student has some understanding of the question or problem.

  • Calculations are not correctly done.
  • Analysis is accurate to within 20% error or less
  • Laboratory report is missing one or two parts.
  • The response addresses the question.

Level 0

There is evidence that the student has no understanding of the question or problem.

  • The response is completely incorrect or irrelevant or there is no response.

METACOGNITION:

Cognitive Information: I will collect the following information after group problem solving of the worksheet, students will report out:

  1. Describe skills needed to complete this task.
  2. Explain how they solved the problems

After the laboratory activity, students will discuss sources of error in calculation and in experimental protocol.

Laboratory report will be scored according to the rubric.

RESULTS:

Organize: I will use the following chart to display student data for each time that I assess and score the same learning standard(s):

Data-Driven Results Disaggregated by Gender and All Students

Content Standard:

STANDARD 5.6 CHEMISTRY: All students will gain an understanding of the structure and behavior of matter.

Strand B. Chemical Reactions: Building upon knowledge and skills gained in preceding grades, by the end of Grade 12, students will:

1. Explain that the rate of reactions among atoms and molecules depends on how often they encounter one another and that the rate is affected by nature of reactants, concentration, pressure, temperature, and the presence of a catalyst.

Students

Scoring Results

Last Name and First Name

Male

Female

All Students

1. Student 1

2

   

2

2. Student 2

   

4

4

3. Student 3

   

 4

4

4. Student 4

1

  

1

5. Student 5

   

3

3

6. Student 6

   

4

4

7. Student 7

3

  

3

8. Student 8

   

3

3

9. Student 9

   

2

2

10. Student 10

3

   

3

11. Student 11

   

4

4

12. Student 12

   

4

4

13. Student 13

3

  

3

14. Student 14

   

3

3

15. Student 15

   

3

3

16. Student 16

  

3

3

17. Student 17

  

4

4

18. Student 18

3

   

3

19. Student 19

   

4

4

20. Student 20

   

4

4

21. Student 21

  

4

4

22. Student 22

   

4

4

23. Student 23

  

3

3

24. Student 24

  

4

4

# Of students at the Advanced Performance Level

   

  

11

# Of students at the Proficient Performance Level

   

  

10

# Of students at the Basic Performance Level

   

   

2

# of Students equal to or greater than the Proficient Level

  

  

21

Analyze:

Contributing factors:  This was a complex and interdependent series of tasks, involving computations and hands-on activities.  The success of the laboratory activity depended on the accuracy of the computations.  The success of the laboratory report depended on the students having already mastered the protocol for writing a complete and acceptable lab report.  By this time of the year, these students should have achieved the preliminary skills to accomplish this activity successfully.  The students who were less successful are those who need more motivation to concentrate on the assigned task.

Reflect: The combination of computation and laboratory activity is good because it allows several different learning modes throughout the same lesson.  The problem with the students who lost focus, I think, is that there was too much time between the conceptual and computational aspects of the topic and the application in the laboratory.  For those few students, an intermediate assessment might have been helpful.

Summarize: This activity was successful.  Since this topic is essential to any Chemistry Laboratory work, students must become proficient in the skills taught in this lesson.  Molarity is a difficult concept, and by applying it to making and mixing different solutions, even students who do not quite grasp all of the ramifications of the theory, can use the concepts involved and apply them.