Flashcards on Understanding Acid-Base Indicators and pH
Understanding Acid-Base Indicators and pH: A Student's Guide
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Acid–Base Indicators
16 cards
Card 1
Question: What is an indicator?
Answer: A substance from plants that changes colour when mixed with different types of solutions, showing if they are acidic, alkaline or neutral.
Card 2
Question: Name two plants or natural sources that can be used as indicators.
Answer: Red cabbage and lichen (used to make litmus).
Card 3
Question: What colour does litmus turn in acidic solutions?
Answer: Red.
Card 4
Question: What colour does litmus turn in alkaline (basic) solutions?
Answer: Blue.
Card 5
Question: What colours can litmus be before testing?
Answer: Red, blue, or sometimes purple.
Card 6
Question: How can red cabbage juice behave as an indicator when mixed with different substances?
Answer: It can be red in acid (e.g., vinegar), blue with soap (alkali), and yellow-green with strong alkali (e.g., drain cleaner).
Card 7
Question: What does it mean if an indicator does not change colour when added to a solution?
Answer: The solution is neutral (neither acidic nor alkaline).
Card 8
Question: Give three examples of neutral solutions from the content.
Answer: Pure water, salt solution, and sugar solution.
Card 9
Question: What does methyl orange do in acids and alkalis?
Answer: It turns red in acids and yellow in alkalis.
Card 10
Question: Would methyl orange change colour if pure water is added? Explain briefly.
Answer: No — pure water is neutral, so it does not change the colour of indicators.