This learning module is designed for a honors level high school chemistry class. It covers properties of acids and bases, the Arrhenius acid and base theory, Bronsted- Lowry acid and base theory, conjugate acids and bases, uses of acids or bases, and pH calculations. Before starting this unit, students should have knowledge of concentration and molarity.
Acids and bases are found all around us, and are part of everyday life. Acid-base chemistry is measured on the pH scale, the concentration of hydrogen ions in a solution. Buffers can control pH, whether used in the lab or in the acid-base components of human blood. The role of acids and bases will be shown in food, from the rise of a cake to the making of cheese. In the environment, acid rain plagues industrial portions of the world; the chemical nature of acid rain reactions and the environmental response and impact are part of acid-base chemistry. The understanding of acids and bases is an essential component of chemistry.
This learning module is designed for a high school honors level chemistry course. Before starting this learning module, students should have knowledge of the structure of atoms, ions and molecules, moles, molarity, and chemical reactions.
This learning module covers the definitions of acids and bases, identification of acids and bases in chemical reactions, pH calculations, titrations and neutralization reactions, and the application of acid-base chemistry in our lives.
NGSS Standards Addressed:
(HS-PS1-2) Cross Cutting Concepts: Different patterns may be observed at each of the scales at which a system is studied and can provide evidence for causality in explanations of phenomena.
(HS-PS1-6) DCI In many situations, a dynamic and condition-dependent balance between a reaction and the reverse reaction determines the numbers of all types of molecules present.
HS-ETS1-1 Engineering Design Analyze a major global challenge to specify qualitative and quantitative criteria and constraints for solutions that account for societal needs and wants.
21st century Skills:
Collaboration.1 Work effectively, flexibly, and respectfully with others. Value individual contributions and make compromises. Share responsibility.
Communication.1 Communicate effectively, including using technology, for various purposes, and in diverse environments.
Creativity.1 Generate and express new ideas. Fail and learn from failures. Seek feedback on ideas. Take action on new ideas.
CriticalThinking.1 Use valid reasoning, good judgment, and systems thinking to form ideas or solve problems.
Common Core Literacy Standards:
W.HST.9-10.4 Writing in Science and Technical Subjects Production and distribution of writing: Produce clear and coherent writing in which the development, organization, and style are appropriate to task, purpose, and audience.
Instructional Objectives:
Students can use definition of molarity to solve for concentration, moles or Liters of a solution.
Students can identify conjugate acid base pairs.
Students can use patterns to classify molecules.
Students can apply the formula for pH and pOH to calculate either the pH, pOH, [H+], or [OH-] for a solution.
Students can identify properties of acids and bases.
Students can calculate the concentration of an unknown using titration data.
Students can research an application of acids and bases.
By the end of this update, you will be able to define acids and bases and identify their properties.
Read the following text and watch the videos below.
Text adapted from Chemistry: Challenges and Solutions. Unit 10, the Voyage of the Proton. Annenberg Foundation 2017.
Acids and bases include many familiar substances, such as vinegar (an acid) and baking soda (a base). Acids have a sharp odor and a sour taste while bases often have a bitter taste to humans.
To better understand what makes a compound an acid and not a base, we should start with the earliest understanding of acids and base. In 1884, the great Swedish chemist Svante Arrhenius (1859–1927) became the first person to clearly define acids and bases. He said that an acid is a molecule that when dissolved in water produces a proton, or it increases the amount of H+ ion. Remember, since most atoms of hydrogen have just one proton in the nucleus (without any neutrons) and one electron, a positive hydrogen ion is just a proton. As such, an Arrhenius acid is a molecule that when it is dissolved in water, increases the concentration of H+ ions or can be considered to be a proton donor.
An Arrhenius base is a molecule that dissolves in water to produce a hydroxide ion (OH-) thereby increasing the concentration of hydroxide ions in aqueous solution. One example is lye (NaOH), also known as sodium hydroxide or caustic soda, which is quite dangerous and caustic. Lye is used to make soap, and it is a common component in chemical mixtures used to clean ovens and unclog drains. Sodium hydroxide dissolves into two ions easily in water as shown in the chemical equation here: NaOH(s) → Na+(aq) + OH-(aq).
Unfortunately, Arrhenius wasn't completely correct in the way he described the chemistry of acids. The problem is a proton is not stable unless it is isolated in a vacuum, and it quickly attaches itself to another molecule. Since nearly all acid-base chemistry is done in aqueous solution, the water molecule is the stable preferred home of the positively-charged proton. So the proton will become associated with an intact water molecule to form what is called a "hydronium ion" (H3O⁺).
The chemical similarities to acids to each other and bases to each other, give them similar properties.
| Characteristics of Acids | Characteristics of Bases |
| Sour Taste | Bitter taste |
| React strongly with metals | Feel slippery |
| Can burn your skin | Can burn your skin |
| Turn blue litmus paper red | Turn red litmus paper blue |
The following websites and video contain more information on acids and bases. Read the information provided then complete the Knowledge Survey to demonstrate the information you learned from the reading.
ThoughtCo "Ten Facts about Acids and Bases"
LibreText "Overview of Acids and Bases"
By the end of this update, students will understand the definition and properties of acids and bases.
In this first update, student should be reading to get a basic understanding of the definitions of acids and bases. This information is important for students to understand to gain the background knowledge needed to be able to identify the chemical structures that define acids or bases. Students should read the text in the update and read through the different websites that are linked at the end. Encourage the students to take notes while they are reading, and if you have time in class, you may lead a class discussion on the content.
After they have read the content, they should take the knowledge survey. This survey should be used as a formative assessment, and the results should be used to guide additional instruction.
By the end of this unit, you will be able to identify some different ways acid/base reactions affect your daily life.
From reactions that occur in the body, to industry, acid-base chemistry is integral to our daily lives. Watch the video: CChemistry Challenges and Solutions by Annenberg Learner, then read the articles linked below.
Chemistry At Work: Swimming Pool Chemistry
24 Hours: Your Food on the Move
Sinkholes: Chemistry Goes Deep
Create an Update: Research one of the applications of acid/base chemistry from either the videos or articles and summarize your findings in an update. Include your personal connection to the research. How does this application affect your daily life?
Comment on 2 other students updates. Did their findings surprise you? What questions arose from reading the update? What connections can you make with the research and your life?
By the end of this unit, students will understand and research how acid/base chemistry applies to their daily lives.
In this update, students will watch a video recorded from Annenberg Learning. It comes from the video series "Chemistry Challenges and Solutions". This video series instructional goals are as follows:
1. To teach basic chemistry principles using only basic mathematics through text, illustrations, animations, and video. The multimedia format of the course allows learners many modalities and entry points to topics.
2. To motivate students to learn chemistry by demonstrating its relevance to real-world problems, showing chemists as role models in improving human lives. Video profiles of science research teams, as well as numerous sidebars and historical examples in the text, further the objective of humanizing science.
3. To teach about the nature of science by linking key modern concepts to the historical development of chemical ideas. Past discoveries are placed in context of continually evolving models, which though incomplete or incorrect by today's standards, serve to advance the field in spite of their limitations.http://learner.org/courses/chemistry/about/about.html
After the videos, there are 3 different articles that show other applications of acid-base chemistry. For their update, students are to choose one of the applications that in the videos or articles and further research the chemistry and how it applies to their lives.
This update is designed to have students start to see relevance of chemistry in their lives. It will serve as a starting point for the students peer-reviewed project. In their project, students will research an application of acid base chemistry in-depth. By creating an update, and reading other students updates, they will be able to get ideas for topics on their future research project.
By the end of this update, you will be able to identify acids, bases, and their conjugate acid/base pairs in a chemical reaction.
Acids and bases play an important role in our lives. Numerous biological processes, industrial applications, and even environmental problems are a function of the acidity or basicity of aqueous solutions. It is important to understand what makes a substance behave as an acid or a base when dissolved in water.
Look at the following table of common acids and bases.
Looking at the chemical formulas for the acids and bases, you should see that the acids all start with the H+ ion and the bases all end with the hydroxide (OH-) ion. In 1903, Svante Arrhenius won the Nobel Prize in Chemistry for defining acids and bases in terms of the ions produced. An Arrhenius acid is any substance that produces hydrogen ions [or hydronium ions (H3O+) a hydrogen ion attached to a water molecule] when dissolved in water. An Arrhenius base is any
substance that produces hydroxide ions when dissolved in water. While the Arrhenius definitions of acids and bases is useful, it is limited. Johannes Brønsted and Thomas Lowry developed more general definitions for acids and bases using H+ ion (proton) transfer as the focus.
Study the following sets of reactions:
Look at the acids in each of the reactions above. An acid is the substance that loses a proton. During the reaction all of the acids in the reactions above have lost a proton.
Bases are defined as proton acceptors. Each of the bases in the reaction above gain an H+ ion during the reaction.
When an acid loses a proton, it becomes a conjugate base. When a base gains a proton, it becomes a conjugate acid.
Practice identifying conjugate acid/base pairs by studying the quizlet avaliable at this link. After you have practiced, complete this self-assessment available at this google form.
Comment: What difficulties do you have identifying properties of acids and bases and conjugate acid/base pairs? What successes are you having?
By the end of this update, students will be able to identify conjugate acid/base pairs in a chemical reaction.
In this update, students will read and watch a video about identifying conjugate acid base pairs. This skill not only increases their general knowledge of acids and bases, but also works on building the skill of recognizing patterns.
After they have read the information, they are asked to practice identifying acid/base pairs by completing a Quizlet on this topic. Quizlet is a free interactive flashcard program that students can use to help them learn and memorize vocabulary terms.
Finally, students will be asked to self-assess their progress in the unit by completing google forms, and reflecting in the comment section of this update. Teachers can customize this google form editing a copy available here.
By the end of this update, you will be able to calculate the pH, pOH, [H+], or [OH-].
Watch the videos below on the pH scale and calculating the ph of solutions.
This Khan Academy resourcee also provides a useful tutorial on calculating using pH calculations.
After you have learned about how to calculate pH, go to the PhET simulation on pH to explore the simulation.
Update: Use the simulation and write an update on one of these topics:
In your update use evidence from the simulation to support your ideas. Include screenshots or screencasts.
Comment on 2 other students' updates. How were your findings similar or different? Did you get any different results from the simulations that led you to a different conclusion.
By the end of this update, students will be able to calculate pH, pOH, [H+] or [OH-] and determine the relationship between the concentrations of [H+], [OH-] and the strength acids or bases.
They will explore a PhET simulation that relates the concentration of ions and the pH of many household substances. This simulation allows students to visualize the concentrations of molecules at different pH's.
Students working in class, should work in a small group with the simulation to encourage discussion between peers to encourage a deeper understanding of the simulation.
By the end of this update, you will be able to experimentally determine the concentration of an unknown acid or base using a titration.
A titration is a technique where a solution of known concentration is used to determine the concentration of an unknown solution. Typically, the titrant (the know solution) is added from a buret to a known quantity of the analyte (the unknown solution) until the reaction is complete. Knowing the volume of titrant added allows the determination of the concentration of the unknown. Often, an indicator is used to usually signal the end of the reaction, the endpoint.
Watch the following video on performing a titration.
Now complete the tutorial and simulation from the Royal Society of Chemistry. Choose QuickStart and complete all 4 tutorials.
Comment below: How many points did you earn in the simulation? What levels were you able to complete? What levels did you need to make multiple attempts? What is something that you learned from the simulation?
By the end of this lesson, students will be able to use titration data to calculate the concentration of an unknown acid or base.
Students will use a titration simulation developed by the Royal Chemistry Society to learn how to complete different titrations. During the simulation, there are multiple checkpoints with graded questions to formatively assess and give students feedback throughout the simulation.
The simulation is divided into 4 levels with each taking approximately 30 minutes to complete. Students can complete 1, 2, 3, or all 4 depending on how much time is available to spend on the titration.
Each of the 4 levels has a different storyline for students to follow.
Level 1 is the contaminated stream (Strong acid / strong base titration) This level is set within the context of a tanker spillage contaminating a stream with hydrochloric acid. The student is tasked with determining the concentration of the hydrochloric acid in the stream and if it is within acceptable limits.
Level 2 is an aspirin titration (weak acid / strong base titration). This level enables the student to perform a weak acid / strong base titration to determine the amount of aspirin in a consignment of aspirin tablets.
Level 3 is a hair product titration (weak base / strong acid titration). This level is a weak base / strong acid titration problem set within the context of analysing a consignment of hair product for the concentration of ammonia in order to determine if it is within safe limits.
Level 4 is an iron supplement tablets titration (KMnO4 redox titration). This level requires the student to undertake a redox titration to determine the Fe2+ (aq) concentration in iron supplementary tablets. The level concludes with an activity to summarise the techniques and steps common to volumetric analysis.
By the end of this update, you will be able to understand the issue of acid rain and ocean acidification and analyze possible solutions to these issues.
Watch the following videos on acid rain and ocean acidification.
Now, work with a partner or small group to research and analyze possible solutions to reducing ocean acidification and acid rain or reducing their effects on the environment. These solutions could be large-scale (to address the problem for large areas of the planet) or small scale (to address the problem for a small area or population).
Update: Create an update that summarizes your findings. Include the strengths and weaknesses of the solution, its over all effectiveness and its feasibility.
Comment on two other groups updates. How did their research make you think differently about the problem? Do you have any questions or ideas about their research?
By the end of this update, students will be able to understand the issue of acid rain and ocean acidification and analyze possible solutions to these issues.
Students will be encouraged to work together to research and analyze possible solutions to reducing ocean acidification and acid rain or reducing their effects on the environment.
The teacher will be able to assess their learning by reading their updates and their comments on peers updates.
By the end of this update, you will create an original work on the application of acids or bases in the world.
Research choice: Acid Rain, Ocean Acidification, Acids/bases use in agriculture, Acids or bases and your health, Acids and bases in cooking, Acids and bases and engineering or any other application of acids or bases in real life. Your work should be at least 1500 words and include 5 media elements. It should include:
Work will be peer reviewed and self reviewed. You will be expected to edit and revise after the peer reviews.
By the end of this update, students will create an original work on the application of acids or bases in the world. This work will allow the students to apply their knowledge of acids and bases to a issue of their choice.
Research choice: Acid Rain, Ocean Acidification, Acids/bases use in agriculture, Acids or bases and your health, Acids and bases in cooking, Acids and bases and engineering or any other application of acids or bases in real life. The work should be at least 1500 words and include 5 media elements.
Work will be peer-reviewed and self reviewed according to the rubric.
Students will be expected to edit and revise after the peer reviews.
By the end of this update, you will present and listen to other's research and works.
Create an update with a link to your work.
You should develop a 5-6 minute presentation of your research. Presentations can be live (if in class) or recorded and submitted through the update. Students should comment on 3 other students presentation.
Final Update: Create a new update where you write a reflection about what you learned in the unit.
By the end of this unit, students communicate their research, listen to others presentations, and write a reflection on what they learned in the unit.
If in class, students can give their presentation live while displaying their work. However, it the student is taking the class remotely, they may record a video of their presentation and upload it into an update.
After the students have listened to each other's presentations, they should comment on their classmates works.
Finally, for their last update, students should write a reflection on what they have learned in the unit. The reflection will act as a final assessment for student learning in the unit.
References:
Chemistry. (n.d.). Retrieved from http://learner.org/courses/chemistry/text/text.html?dis=U#=Ym5WdElURS9NU289
Chemistry: Challenges and Solutions. Unit 10, the Voyage of the Proton. Annenberg Foundation 2017.
Chemistry at Work: Swimming Pool Chemistry. (1983, April). Retrieved from https://www.acs.org/content/dam/acsorg/education/resources/highschool/chemmatters/articlesbytopic/acidsandbases/chemmatters-april1983-swimming-pool.pdf
Explains, P. D. (2016, March 28). Acid-Base Titration. Retrieved from https://www.youtube.com/watch?v=dLNsPqDGzms
Geographic, N. (2018, February 27). What is Acid Rain? | National Geographic. Retrieved from https://www.youtube.com/watch?v=1PDjVDIrFec&t=13s
GlobalClimateNews. (2012, January 02). NOAA Ocean Acidification - The Other Carbon Dioxide Problem. Retrieved from https://www.youtube.com/watch?v=MgdlAt4CR-4&t=13s
Malik, A. (2017, April 11). Acids and Bases Explained in Under 10 minutes. Retrieved from https://www.youtube.com/watch?v=N-WaZRXf0cE
Next Generation Science Standards. (2019, April 09). Retrieved from https://www.nextgenscience.org/
PH, pOH, and the pH scale. (n.d.). Retrieved from https://www.khanacademy.org/science/chemistry/acids-and-bases-topic/acids-and-bases/a/ph-poh-and-the-ph-scale
Rohrig, B. (2014, April/May). Sinkholes: Chemistry Goes Deep. Retrieved from https://www.acs.org/content/dam/acsorg/education/resources/highschool/chemmatters/articlesbytopic/acidsandbases/chemmatters-april2014-sinkholes.pdf
Science & Technical Subjects. (n.d.). Retrieved from http://www.corestandards.org/ELA-Literacy/RST/
Science, B. (2013, May 01). Acids, Bases, and pH. Retrieved from https://www.youtube.com/watch?v=Xeuyc55LqiY
Sciencepost. (2013, May 25). Calculating the pH of Acids, Acids & Bases Tutorial. Retrieved from https://www.youtube.com/watch?v=1uKtNlPLPZw
Titration Screen Experiment. (n.d.). Retrieved from http://www.rsc.org/learn-chemistry/resources/screen-experiment/titration/experiment/2
Trout, L. (2012). POGIL activities for high school chemistry. Batavia, IL: Flinn Scientific.
pH Scale 1.2.18. (n.d.). Retrieved from https://phet.colorado.edu/sims/html/ph-scale/latest/ph-scale_en.html