Implement this lesson:
This should be one of the first lessons taught to give students a robust understanding of what pH is. This is a really great lesson for students who do not have a robust understanding of pH
Learning objective:
Students will be able to recognize that pH is one way scientists measure ocean acidification, understand the pH scale, acids and bases, understand that a small shift in the pH scale represents a much large shift in the chemical balance
Next Generation Science Standards (NGSS)
Common Core ELA Standards
Informational Text Grades 4-8:
1 – Refer to details and examples in a text when explaining what the text says explicitly and when drawing inferences from the text 4 – Determine the meaning of general academic and domain-specific words or phrases in a text 7 – Interpret information presented visually, orally, or quantitatively and explain how the information contributes to an understanding of the text in which it appears.
Writing Standards Grades 4-8:
1 – Write opinion pieces on topics or texts, supporting a point of view with reasons and information 2 – Write informative/explanatory texts to examine a topic and convey ideas and information clearly 4 – Produce clear and coherent writing in which the development and organization are appropriate to task, purpose, and audience
Common Core Math Standards
Mathematical Practices:
Construct viable argument and critique the reasoning of others Attend to precision Measurement and Data Grades 4-5 Represent and interpret data
Next Generation Science Standards
4 Structure, Function, and Information Processing 4-LS1-1 Construct an argument that plants and animals have internal and external structures that function to support survival, growth, behavior, and reproduction
Science and Engineering Practices: Engaging in Argument from Evidence
Crosscutting Concepts:
Cause and Effect Systems and System Models 3-5 Engineering Design 3-5ETS1-2 Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem.
Science and Engineering Practices Constructing Explanations and Designing Solutions
Crosscutting Concepts:
Influence of Science, Engineering, and Technology on Society and the Natural World MS Human Impacts MS-ESS3-3 Apply scientific principles to design a method for monitoring and minimizing a human impact on the environment
Science and Engineering Practices: Constructing Explanations and Designing Solutions
Crosscutting Concepts:
Cause and Effect Influence of Science, Engineering, and Technology on Society and the Natural World
Texas Essential Knowledge and Skills (TEKS)
K.6A use the senses to explore different forms of energy such as light, thermal, and sound
K.9B examine evidence that living organisms have basic needs such as food, water, and shelter for animals and air, water, nutrients, sunlight, and space for plants
K10B identify basic parts of plants and animals
1.6(A) identify and discuss how different forms of energy such as light, thermal, and sound are important to everyday life
1.10(A) investigate how the external characteristics of an animal are related to where it lives, how it moves, and what it eats
2.9(A) identify the basic needs of plants and animals
2.9(B) identify factors in the environment, including temperature and precipitation, that affect growth and behavior such as migration, hibernation, and dormancy of living things
2.9(C) compare the ways living organisms depend on each other and on their environments such as through food chains
3.9(A) observe and describe the physical characteristics of environments and how they support populations and communities of plants and animals within an ecosystem
5.9(A) observe the way organisms live and survive in their ecosystem by interacting with the living and nonliving components.
5.9(B) describe the flow of energy within a food web, including the roles of the sun, producers, consumers, and decomposers
5.9(C) predict the effects of changes in ecosystems caused by living organisms including humans, such as the overpopulation of grazers or the building of highways
5.9(D) identify fossils as evidence of past living organisms and the nature of the environment at the time using models
Overview
The most simple way to explain pH is to state how acidic or basic an item is. A scale of 0 to 14 is used to determine exactly how acidic or alkaline a substance is with 7 being neutral. Bases are 7-14, with 14 being the strongest base. Acids are 0-7 with 0 being the strongest acid. An acid is typically determined by how many hydrogen ions it has. If a substance contains a lot of them, then it is a strong acid. Substances with a a lot of hydroxide ions are strong bases.
Materials:
- pH indicator (I prefer red cabbage juice for this lab)
- vinegar
- lemon juice
- apple juice
- distilled water
- salt water
- bleach
- milk of magnesia
- baking soda
- alka seltzer
- small cups such as beakers or dixie cups
- eye dropped
Advanced Prep:
- Place vinegar, lemon juice, apple juice, distilled water, salt water, bleach, milk of magnesia, baking soda, and alka seltzer in a cup. With the alka seltzer pour water over it.
- Pour pH indicator solution in a separate cup
Procedure:
- Students place a drop of each liquid on a clean surface such as a cookie tray or plate.
- Students then add a drop of the pH indicator solution on each liquid drop. The drop will turn a different color.
- Students try to create a ‘rainbow’ using the different liquids
- Students determine which is the strong acid and base
Questions to Ask:
Pre-experiment
- Do you know what an acid is? A base? Would you like to learn about it?
- Did you know there are acidic and basic substances we use and possibly eat each day?
- Do you know what is causing this change in ocean pH?
Post-experiment
- How did you determine which liquid is the strongest acid and base?
- Why do you think the colors changed
Extensions:
- Students test out different liquids
Evaluation:
- Students draw a picture of their results and order the cups from strongest acid to strongest base.
- Approximate pH of Everyday or Household Objects • larger battery =2.2 • vinegar= 2.8 • coca-cola = 2.5 (classic) can range up to 4.2 with other brands • lemon=2.3 • grapefruit = 3.0-3.3 • orange= 3.0-4.0 • apple= 3.5 • banana= 5.0 • milk= 6.5 • water bottle pH= 7 (6.5-8 depending on brand) • human blood= 7.4 • ocean pH= 8.1 now 8.0 • baking soda= 8.4 • Tums, antacid= 10.5 • bleach= 12.6 • drain cleaner = 14
