Chemistry
Standard 6, Objective 1
Title: Solutions Everywhere
Description: Students will discover how the percent concentration for solutions is widely used in foods and medicines. This activity will be used as a review after the concept has been taught. The assignment will give the students a real world application.
Time Needed: 30 minutes in class plus homework time
Prior knowledge: Student should know how to recognize percent concentration.
Materials: student sheet (below)
Procedure:
1. This is a homework assignment that will be done by individual students. This assignment will be given to familiarize students with the importance of percent concentration in describing the strength of medicines and the components of food.
2. Have the students write down the product from which the label came. They will cut out the lab and past it in the box provided. They should fill in the name and percent concentration of the substance they were interested in in the spaces to the right.
3. When the students return with this homework assignment, have the student get in groups to share the products they used and what percentages they found. You can use this opportunity to have the students correct each other’s work so it is easier for you to correct as a teacher.
4. Vote for the most interesting product.
Scoring Guide: After the students have helped each other make corrections, grade each blank (product label, percent concentration) as one point. For an extra credit opportunity, make each label worth one point.
The next page is a blank worksheet you can copy and give to your students to use. Copy the same page on both the front and the back (the back is just the extra credit side). Also included is an example. Showing students an example will result in less confusion and better work.
Student SheetName______
Title: Solutions Everywhere
Introduction: In this activity you will see how percent concentration is widely used to document the amount of different chemicals or substances found in medicines or foods. Here is some information on skin creams to treat acne.
Medicated products contain a chemical that dries up a pimple while acting as an exfoliant. The most common ingredients used for this purpose are are benzoyl peroxide and salycic acid. People with sensitive skin should choose a product that contains salycic acid over one containing benzoyl peroxide. The amount of drying chemical added to a product is measured in terms of percentage, with the stronger creams having a higher percentage (or concentration) of the active ingredient. Contrary to the "more is better" instinct, the highest concentration is not always the most effective, it all depends on your skin type and the sort of acne you are dealing with. Some acne will not respond well to OTC products and must be treated by a doctor or dermatologist (skin specialist).
Notice how important it is to have the correct chemical and the correct percentage of it for your skin.
Procedures:
1. Find 5 products at home with percentage concentration on their labels. They can be foods, medicines, cleaning products or anything with a label and percentages. Do not take all your examples from the same group.
2. Cut out the information about percentages and glue to this paper.
3. Next to the label, write the name of the substances you found interesting and comment on it. Was it what you expected? Why or why not?
4. Bring your work to school and plan on sharing with your class.
5. Answer the questions after you have shared results with your classmates.
Data:
Label from:
Label:
Label from:
Label:
Label from:
Label:
Label from:
Label:
Label from:
Label:
Analysis:
1. Which substances contain high percentages of “inactive” or “inert” ingredients?
2. Why do you think the percentages of “inactive” ingredients in those substances were so high?
3. How do percentages of substances in foods help you make wise food choices?
4. Why is it often more important to look at the percent concentration than the total mass or volume of the substance?
Conclusion: