Indicators: Acids, Bases, and Beyond!

• newEditor
• Chemistry
• Secondary Education

Indicators: Acids, Bases, and Beyond!

What do you already know about indicators used to test acids and bases?

Learning Objective

At the end of the lesson you will be able to identify and explain the use of natural, synthetic, and olfactory indicators in detecting acids and bases.

Big Question: Entry Ticket

Suppose you accidentally spill lemon juice on your shirt and it turns pink. What might this indicate? How could you te?st what caused this colour change

Pre-requisite Check

1. What is an acid and what are its common properties? 2. Name at least two bases you know from daily life. 3. Ho?w do you think scientists identify acids and bases? 4. Why do you think indicators are important in chemistry

Learning Outcomes & Success Criteria

Explain

Describe what indicators are and list types (natural, synthetic, olfactory).

Interpret, Compare/Contrast, Evaluate

Interpret how indicators work. Compare different indicators. Evaluate scenarios using indicators.

Vocabulary: Key Terms

Acid: Substances with pH less than 7. Base: Substances with pH greater than 7. Indicator: Substance used to detect acids or bases. Natural Indicator: Derived from plants (e.g., litmus, turmeric). Synthetic Indicator: Made in labs (e.g., phenolphthalein, methyl orange). Olfactory Indicator: Changes smell in presence of acid/base.

Lesson Development: Think-Pair-Share

Task: Observe changes when turmeric, litmus paper, and phenolphthalein are added to various substances. Discuss in pairs: Which is the best indicator for each substance? Share findings with the class.

Engage: Must, Should, Could Activity

Must: Identify at least one natural and one synthetic indicator. Should: Predict the colour change for different indicators. Could: Explain the role of olfactory indicators using a real-life scenario.

Drop Everything and Read!

Read the handout: 'Indicators in Action'. Answer: 1. Why do indicators show different colours? 2. Describe an experiment where an indicator is used.

Explore: Research and Present

Task 2: In pairs, research any one indicator from today’s lesson. Prepare a mini-poster or a 2-minute speech on its real-world uses and how it works. Use reference handouts provided.

AFL/Plenary: Exit Ticket

On a sticky note, answer: Which indicator would you choose to test an unknown solution and why?

Explore for Extended Learning

Research: Are there indicators for other types of substances? Investigate pH sensors, digital indicators, or bio-indicators from nature.

Lesson Reflection: What Went Well?

Share what you found most interesting about today’s activities. How did group work help you understand indicators and their uses?

Write down 3 things you learned in this lesson.

Write down 2 things you want to know more about.

Ask 1 question about something you haven't quite understood yet.