Class 7th Science NCERT Chapter 5
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Topics to study from the chapter "Acids, Bases and Salts" along with 1-2 line summaries for revision:
1. Acids and Bases
– Acids like curd, lemon juice, and vinegar taste sour, while bases like baking soda taste bitter and feel soapy. Indicators help determine the acidic or basic nature of substances.
2. Natural Indicators
– Litmus, a natural dye, changes color to red in acids and blue in bases. Turmeric is another natural indicator that changes color to red with bases.
3. Acids Found in Nature
– Various acids like acetic acid in vinegar, citric acid in citrus fruits, and lactic acid in curd are found naturally. Bases like calcium hydroxide in lime water and sodium hydroxide in soap are also natural.
4. Experiments and Observations
– Activities using litmus and turmeric paper to test substances for acidity or basicity help understand the properties of acids, bases, and neutral solutions.
5. Neutralization
– The process of neutralization involving adding an acid (like dilute hydrochloric acid) to a base (like sodium hydroxide) till the solution turns pink with phenolphthalein demonstrates chemical reactions between acids and bases7.
What are the characteristics of substances that taste sour according to the chapter?
What is litmus and how does it act as a natural indicator?
Describe the process and results of the turmeric test mentioned in the chapter.
What are neutral solutions, and how are they identified?
How does phenolphthalein act as an indicator for acidity and basicity in the neutralization process described in the chapter?
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