ACID BASE AND SALTS
Intext Questions
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- You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
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2. Why should curd and sour substances not be kept in brass and copper vessels?
3. Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example. How will you test for the presence of this gas?
4. Metal compounds A reacts with dilute hydrochloric acid to produce effervescence. The gas evolved extinguishes a burning candle. Write a balanced chemical equation for the reaction if one of the compounds formed is calcium chloride.
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5. Why do HCl, HNO₃, etc., show acidic characters in aqueous solutions while solutions of compounds like alcohol and glucose do not show acidic character?
6. Why does an aqueous solution of an acid conduct electricity?
7. Why does dry HCl gas not change the colour of dry litmus paper?
8. While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?
9. How is the concentration of hydronium ions (H₃O⁺) affected when a solution of an acid is diluted?
10. How is the concentration of hydroxide ions (OH⁻) affected when excess base is dissolved in a solution of sodium hydroxide?
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11. You have two solutions, A and B. The pH of solution A is 6, and the pH of solution B is 8. Which solution has more hydrogen ion concentration? Which of these is acidic and which one is basic?
12. What effect does the concentration of H⁺ (aq) ions have on the nature of the solution?
13. Do basic solutions also have H⁺ (aq) ions? If yes, why are these basic?
14. Under what soil condition do you think a farmer would treat the soil of his fields with quicklime (calcium oxide) or slaked lime (calcium hydroxide)?
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15. What is the common name of the compound CaOCl₂?
16. Name the substance which on treatment with chlorine yields bleaching powder.
17. Name the sodium compound which is used for softening hard water.
18. What will happen if a solution of sodium hydrogen carbonate is heated? Give the equation of the reaction involved.
19. Write an equation to show the reaction between Plaster of Paris and water.
Exercise Questions
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A solution turns red litmus blue. Its pH is likely to be:
(a) 1 (b) 4 (c) 5 (d) 10A solution reacts with crushed egg-shells to give a gas that turns lime water milky. The solution contains:
(a) NaCl (b) HCl (c) LiCl (d) KCl10 mL of a solution of NaOH is found to be completely neutralised by 8 mL of 0.1 M HCl solution. The concentration of the NaOH solution is:
(a) 0.08 M (b) 0.1 M (c) 0.125 M (d) 0.15 MWhich one of the following types of medicines is used for treating indigestion?
(a) Antibiotic (b) Analgesic (c) Antacid (d) AntisepticWrite word equations and then balanced chemical equations for the reactions taking place when:
(a) Dilute sulphuric acid reacts with zinc granules.
(b) Dilute hydrochloric acid reacts with magnesium ribbon.
(c) Dilute sulphuric acid reacts with aluminium powder.
(d) Dilute hydrochloric acid reacts with iron filings.Compounds such as alcohols and glucose also contain hydrogen but are not categorised as acids. Why?
Why does distilled water not conduct electricity, whereas rainwater does?
Why do acids not show acidic behaviour in the absence of water?
Five solutions A, B, C, D, and E have pH values of 2, 7, 10, 13, and 6, respectively. Which solution:
(a) Is strongly acidic?
(b) Is strongly basic?
(c) Is neutral?
(d) Is weakly acidic?
(e) Is weakly basic?Equal lengths of magnesium ribbons are taken in test tubes A and B. Hydrochloric acid (HCl) is added to test tube A, while acetic acid (CH₃COOH) is added to test tube B. In which test tube will the fizzing occur more vigorously and why?
Fresh milk has a pH of 6. How do you think the pH will change as it turns into curd? Explain your answer.
A milkman adds a small amount of baking soda to fresh milk. Why does this milk take a longer time to set as curd?
Plaster of Paris should be stored in a moisture-proof container. Explain why?
What is a neutralisation reaction? Give two examples.
Give two important uses of washing soda and baking soda.
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