acids, bases and salts — Science STD 10 — Question
Gujarat BoardEnglish MediumSTD 10Scienceacids, bases and salts4 Marks
Question
How are the tests of acid-base done using olfactory indicators ?
✓
Answer
→ "Substances whose odour changes in acidic or basic media are called olfactory indicators." → Acid and base tests can be explained by the following activity using olfactory indicators in laboratory. → First of all take some finely chopped onions in a plastic bag along with some strips can now be used to test for acids and bases. → Take two of these cloth strips and check their odour. → Keep them on a clean surface and put a few drops of dilute $HCl$ solution on one strip and few drops of dilute $NaOH$ solution on the other. → Rinse both cloth strips with water and again check their odour. Note your observations. → Take some dilute $HCl$ solution in one test tube and dilute $NaOH$ solution in another. Add a few drops of dilute vanilla essence to both test tubes and shake well. check the odour once again and record changes in colour if any. → Similarly test the changes in the colour of clove oil with dilute $HCl$ and dilute $NaOH$ solutions. and record your observations. Observations → On the basis of observations of the above activity we can decide that among vanilla, onion and clove, what can be take as olfactory indicators. Conclusion → The substance which possess specific odour in acidic medium and possesses different odour in basic medium, are called Acid-Base olfactory indicators. Observations → On the basis of observations of the above activity we can decide that among vanilla, onion and clove, what can be take as olfactory indicators. Conclusion → The substance which possess specific odour in acidic medium and possesses different odour in basic medium, are called Acid-Base olfactory indicators.
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