Introduction

Acids and bases play a key role in the chemistry that affects your daily life. Many manufacturing processes use acids and bases. Your body needs acids and bases to survive. This WebQuest is designed to allow you to become familiar with the nature of acids and bases, as well as [H⁺], [OH^-], pH , and pOH calculations. In addition, you will examine the issue of acid rain and propose solutions to this potential environmental problem.

The Task

In this WebQuest assignment, you will :

• describe and compare the properties of acids and bases
• describe and compare three models of acids and bases (Bronsted-Lowry, Lewis, Arrhenius)
• distinguish between strong and weak acids and bases
• calculate [H⁺] , [OH ^-], pH, pOH
• classify common substances as acidic or basic
• discuss the potential problem of acid rain.

In addition to your chemistry text, the following websites will be available to you:

• Acid and Base pH Tutorial
• Chem 4 Kids Acids and Bases
• Chemtutor Acids and Bases
• CHEMystery Acids and Bases
• Chem Web Acids and Bases
• pH Calculator Exercise
• Acid Rain 2000
• EPA Acid Rain Site
• SWOOPE Acid Rain Project

 All of these sites have good information that can help you in this project, and many of them have links to other useful sites that are related to acids and bases.

 To do this project, you will first need to assemble into groups of 3. This project can basically (ha-ha) be broken down into 4 assignments:

Assignment 1 In this assignment, your group will construct a visual poster presentation that compares the properties of acids and bases. In addition, you will construct a visual presentation that compares three models of acids and bases: Arrhenius, Bronsted -Lowry, and Lewis. You should be extremely thorough and as detailed as possible. Be as creative as you can, gathering materials from the Internet and outside journal sources . Be prepared to present your findings to the rest of the class. As a group, you may divide up the assignment responsibilities as you decide. Also, each group member should write a brief description (1-2 paragraphs) about their roles and responsibilities within the group regarding this assignment.

Assignment 2 (A)This assignment involves the concentrations of acids and bases. Your group should research the relationship between hydrogen ion concentrations, hydroxide ion concentration, the ion-product constant for water pH, and pOH. Your group should prepare a step-by-step instructional packet that explains:

1. [H⁺ ] and [OH^-]

2. how to solve [H⁺ ] and [OH^-] problems using the ion-product constant for water (K_w).

3. pH, pOH, and the pH scale

4. how to solve pH and pOH problems.

5. how to calculate pH, pOH, [H⁺] , and [OH^-] when given only one of these values.

Your group should approach this packet from the perspective of a good instructor; you want to start with the simplest definitions, examples, and sample problems that you can, and build from there. Your packet should be completed using Claris Works, Microsoft Word, or PowerPoint. Your packet will be submitted to your teacher, where a class "mega packet" will be made.

 Assignment 2 (B) This is an independent assignment involving the calculations you researched for your packet. Each student will complete at least 10 of the pH calculation problems at the following website:  pH Calculator Exercise . You should complete at least 10 problems, with a score of 90% or better. If you have less than 90% after 10, you can either continue to try more problems until you reach 90% or start over. Once you have done this, print your last page and bring it to your instructor. You may use your notes and book for these, but keep in mind that the class will have a quiz on this material following the assignment, so you need to know these calculations like the back of your hand.

 Assignment 3 In this assignment, your group will test the pH of various substances that can be found around your home. Your group should arrange to bring at least 8 common (nonhazardous) substances from your homes, such as hair spray, shampoo, detergent, soap, window cleaner, various fruit and vegetable juices, mouth wash, cologne, deodorant, bleach, soft drinks, milk, etc. You will obtain a pH meter or universal indicator strips from your instructor to test the pH of the substances. Solid substances, such as aspirin, detergents, etc. and thick liquids can be dissolved or diluted in water. Although these substances should pose no harm, every group member should wear lab goggles when handling these substances. After testing and recording the pH values of these substances, your group should design a pH scale that compares the values that you found . You may use posters, PowerPoint, Claris Works, etc. Your group will present your findings to the class. From the group data, a class pH scale will be constructed.

 Assignment 4 Now your group will research the issue of acid rain. Your group is preparing a 10-15 minute report for a "congressional panel " (i.e. class) that is examining this potential environmental problem. Your group's report should include:

1. a detailed explanation of the nature of acid rain, including any chemical processes involved. The causes should be identified, including natural and man-made causes. Assume that the panel has little knowledge of chemistry, and needs thorough details.

2. a description of any possible environmental threats, if they exist. You will need to back up your claims with evidence, citing the research of other experts in this area.

3. potential solutions for the problems presented by acid rain . You should consider the roles of industry, government, and individuals. Make clear, detailed proposals and explain how these proposals can help. Again, cite the opinions of experts.

Since the report has three parts, each group member will report on one part (duh!). Be as creative as you dare to be, using Claris Works, PowerPoint, posters, etc. to make your case.

Your grade will depend upon both group and individual assignments ; you can see how your grade is broken down by clicking on this Project Grading Rubric link. You need to be able to work well with the other members of your group, as well as demonstrate creativity. As always, proper grammar spelling and punctuation are expected. If you have any questions concerning your grade, please ask you instructor.

By the time you have completed this project, you should have an understanding of the nature of acids and bases. You should also be able to calculate the pH and pOH of solutions and use these values to determine if a solution is acidic or alkaline. In addition, you should be able to understand the meaning and implications of acid rain and how it can affect you.