Introduction to Acids and Bases
Strong Acids and Strong Bases
What are Acids and Bases?
Simply put acids and bases are electrolytes that form aqueous solutions with unique properties. A Swedish chemist by the name of Svante Arrhenius was the first person to characterize acids and bases in terms of their chemical properties. Acids and bases play an extremely important role in the lives of all living organisms as we are all sensitive to the acidity of aqueous solutions both in our internal and external environments. Acids and bases are also essential to the proper functioning of natural and synthetic processes that we use everyday.
Simply put acids and bases are electrolytes that form aqueous solutions with unique properties. A Swedish chemist by the name of Svante Arrhenius was the first person to characterize acids and bases in terms of their chemical properties. Acids and bases play an extremely important role in the lives of all living organisms as we are all sensitive to the acidity of aqueous solutions both in our internal and external environments. Acids and bases are also essential to the proper functioning of natural and synthetic processes that we use everyday.
LESSON OVERVIEW (SPECIFIC EXPECTATIONS E1.2, E2.1, E2.4, E3.4, E3.5, E3.6, E3.7)
Diagnostic and Lesson Hook:
At the beginning of this section of the unit, it would be wise to preform a small diagnostic and review content from Grade 11 chemistry before introducing new material. A fun way to accomplish both while keeping the class entertained is to create acid rain as a demonstration or short activity. Introducing the concept of acid rain can pave the way for discussion of the importance of acids and bases in our environment and, if accompanied with Socratic questioning during the demonstration or a worksheet, can also serve as a diagnostic of class recall of previous concepts taught in grade 11 chemistry. Shown below is a video of "Chem Lab Acid Rain", ideally this would be done as a class demonstration or student activity.
At the beginning of this section of the unit, it would be wise to preform a small diagnostic and review content from Grade 11 chemistry before introducing new material. A fun way to accomplish both while keeping the class entertained is to create acid rain as a demonstration or short activity. Introducing the concept of acid rain can pave the way for discussion of the importance of acids and bases in our environment and, if accompanied with Socratic questioning during the demonstration or a worksheet, can also serve as a diagnostic of class recall of previous concepts taught in grade 11 chemistry. Shown below is a video of "Chem Lab Acid Rain", ideally this would be done as a class demonstration or student activity.
Action:
This demonstration provides a lead in for discussion of acids and bases in our everyday lives and the importance of measuring and maintaining acidity levels in our environment It also can be used to start a discussion of the process of measuring acidity levels and the concept of pH and pH meters. Once the demonstration/activity is done, ideally a brief review of the definitions and properties of acids and bases would follow and then an introduction of the concepts of the autoionization of water and strong acids and bases before finishing with pH and pH calculations.
Note: The concept of pH requires students to understand the relationship between logs and exponents as well as being able to preform those calculations using a calculator. It is advisable to review/teach students how to correctly identify and switch between the two both on paper and using a calculator.
In order to have students visualize what is occurring in solution as well as to appeal to multiple intelligences a computer simulation activity can be used to illustrate the concepts discussed above. Click below for a good computer simulation courtesy of the University of Colorado (PhET). Students are able to play with various aqueous solutions and observe the effects of dilution on the resulting H+ and OH- concentrations.
This demonstration provides a lead in for discussion of acids and bases in our everyday lives and the importance of measuring and maintaining acidity levels in our environment It also can be used to start a discussion of the process of measuring acidity levels and the concept of pH and pH meters. Once the demonstration/activity is done, ideally a brief review of the definitions and properties of acids and bases would follow and then an introduction of the concepts of the autoionization of water and strong acids and bases before finishing with pH and pH calculations.
Note: The concept of pH requires students to understand the relationship between logs and exponents as well as being able to preform those calculations using a calculator. It is advisable to review/teach students how to correctly identify and switch between the two both on paper and using a calculator.
In order to have students visualize what is occurring in solution as well as to appeal to multiple intelligences a computer simulation activity can be used to illustrate the concepts discussed above. Click below for a good computer simulation courtesy of the University of Colorado (PhET). Students are able to play with various aqueous solutions and observe the effects of dilution on the resulting H+ and OH- concentrations.
pH Scale Simulation | |
File Size: | 1164 kb |
File Type: | jar |
Misconceptions Addressed: Students commonly believe that pH is a measurement of the degree of acidity of a solution.
Debrief:
Allow for time at the end of the lesson to have students preform their own pH studies. Give each student a few strips of pH litmus paper and have them measure the pH of the school water, their drinks, and/or the teacher's coffee. Then have them determine the concentration of H+ and OH- ions in each beverage using the results found with the litmus paper. Have them had in the calculations at the end of class to check for understanding.
FOPP: Commitment to students and student learning, professional knowledge, professional practice and ongoing professional learning
Debrief:
Allow for time at the end of the lesson to have students preform their own pH studies. Give each student a few strips of pH litmus paper and have them measure the pH of the school water, their drinks, and/or the teacher's coffee. Then have them determine the concentration of H+ and OH- ions in each beverage using the results found with the litmus paper. Have them had in the calculations at the end of class to check for understanding.
FOPP: Commitment to students and student learning, professional knowledge, professional practice and ongoing professional learning
The concept of Acids and Bases can be reinforced in a variety of ways to appeal to all forms of multiple intellegences. Click below for a few resources that can be used in conjunction with a lesson to further demonstrate the concept of Acids and Bases.