Gold Seal Lesson:
Rub-A-Dub-Dub

Copernicus Education Gateway

 

Subject:

Science

Grade:

 

 

9-12

 

 

ICLE Standards:

 

 

Physical Science - Develop an understanding of chemical reactions.

History and Nature of Science - Develop an understanding of science as a human endeavor.

 

 

Performance Task:

 

 

This task requires you to prepare soap from its raw materials using proper laboratory techniques. For this task you will need the following materials:

400 ml beaker Ice water bath Wire gauze
100 ml graduated cylinder Foil cupcake mold Matches
Cheese cloth Bunsen burner
Glass stirring rod Ring stand
You will also need the following chemicals:
Sodium hydroxide Cottonseed oil
Saturated NaCl solution 5% HCl
Phenolphthalein indicator

Follow the procedure given below:

  1. Dissolve 20 g of solid sodium hydroxide in 50 ml of water in a 400 ml beaker. Caution: Sodium hydroxide is very dangerous. It should be handled with gloves, and eye protection should be worn at all times during this activity. Should any sodium hydroxide get on your skin, you should flood the area immediately with running water.
  2. Add 40 ml of cottonseed oil to the sodium hydroxide solution and boil over low heat for 30 minutes, stirring continuously.
  3. After the 30-minute time period, add an additional 40 ml of water and continue the heating and stirring for at least 20 more minutes.
  4. Add 100 ml of saturated NaCl solution, stir and cool the mixture in an ice water bath.
  5. Filter the solid soap through a double layer of cheese cloth squeezing out all of the liquid.
  6. Place the soap back into the beaker and wash it with a mixture of 50 ml of plain water mixed with 50 ml of saturated NaCl solution.
  7. Filter the soap again using the same piece of cheese cloth used before. You should wash the cheese cloth between the two filtrations.
  8. Once again, put the soap back into the beaker, add 20 ml of water, heat and stir until thick.
  9. Pour the soap into a mold and allow it to harden overnight.
  10. Write the reaction for the formation of soap.
  11. Test a soap solution with phenolphthalein solution and record the results.
  12. Add 2 ml of 5% HCl solution to 5 ml of soap solution. What are the results?
  13. Write a chemical reaction equation illustrating the above reaction.
  14. Calculate the theoretical yield and the percentage yield of the reaction.

 

 

Knowledge / Skills:

 

 

Know the symbols that represent one atom or one mole of atoms of an element. Name and write molecular and empirical formulas of chemical compounds. A formula is a statement comprised of chemical symbols that represent the composition of a substance.  (s66

Use stoichiometry to compute quantitative relationships implied by chemical formulas (e.g., find the percent composition by mass of an element in a compound and the simplest ratio in which the atoms combine to form a compound) and chemical equations (e.g.

Follow written directions carefully and accurately.  (ela6)

 

 

Rubric:

 

 

4 Points  =  The student independently follows directions and demonstrates good laboratory techniques in carrying out the preparation of soap. He/she makes a complete and meaningful response to all parts of the task. The student accurately computes the theoretical yield and his/her percentage yield is greater than 50%.


3 Points  =  The student needs some coaching to follow directions in carrying out the preparation of soap. He/she demonstrates good laboratory techniques, but has difficulty responding to all parts of the task. He/she exhibits some lack of understanding of the chemical knowledge inherent in the task. The student needs coaching in computing the theoretical yield and his/her percentage yield is only between 35-50 percent.


2 Points  =  The student has great difficulty in following directions necessary to complete the preparation of soap. He/she displays a lack of good laboratory techniques and shows little understanding of major ideas. The student is unable to respond to most of the task. He/she is unable to compute the theoretical yield and his/her percentage yield is less than 35 percent.


1 Point  =  The student is unable to follow directions accurately. Consequently, he/she has no final product and is unable to complete any of the required tasks. He/she has poor laboratory techniques and ignores laboratory safety. The student's work is disorganized.

 

 

Keywords:

 

 

CHEMISTRY
CHEMICAL BONDS
LAB EXPERIMENTS
MATHEMATICAL EXPRESSIONS
REACTIONS
SCIENTIFIC PROCESS
FOLLOW DIRECTIONS                 
EARTH SCIENCE
SCIENTIFIC INQUIRY

 

 

Grades:

 

 

Kg [] - 1 [] - 2 [] - 3 [] - 4 [] - 5 [] - 6 [] - 7 [] - 8 [] - 9 [X] - 10 [X] - 11 [X] - 12 [X]

 

 

ICLE Application:

 

 

D

 

 

 

 

 

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