Ncert Solution Class 10th Ch-2 Acid Bases and Salts), This Chapter actually deals with the different types of substance nature. Mainly in this chapter, we are going to discuss the acid and the basic nature of different Compounds.
In this chapter, You are going to learn about the nature and behavior of Acids, bases, and salts. How they Chemically react together or with different things. Mainly you’re going to deal with the Chemical properties of Acids, Bases, and salts. in the Previous Classes, you have studied about the Physical properties of the Acids, Bases, and Salts.
Example:- Acids are sour in taste, Whereas Bases are Bitter in Taste and Salts are basically in Neutral in nature. But in this chapter, you’re going to deal with the Chemical properties with the Acids, bases and the Salts.
So Students Let’s start our today’s topic that is Ncert Questions of Class 10th chapter-2 (Acid bases and Salts).
Page No. 18. Ncert Solution Class 10th Ch-2 Acid Bases and Salts
Ans:- You need to notice on the following processes/reactions with red litmus paper to find out, which test tube contains Acidic, Basic or Dilute Solution.
Let’s suppose, Put red litmus paper to 1st Solution.
- If the red color litmus paper changes to blue color, then the solution will be basic of nature.
- If the color of litmus paper changes to red (from blue) color then the solution will be acidic in nature.
- If you did not observe any change in the color then the solution will be distilled water.
Page no. 22 Questions/Answers Chapter-2 (Acid, bases, and Salts.)
Q1.Why should curd and sour substances not be kept in brass and copper vessels?
Ans:- Curd or Sour Substances should not be kept in brass and copper vessel because, Curd or sour Substances are Acidic in nature and As you know that, Acid do the reaction with metals and the reaction can turn the food into the poisonous substance, which can cause food poisoning.
Ans:- Mainly, H2 (hydrogen gas) releases when acids react with the Metal. Metal + Acid/base ——> Salt + H2 (g).
Example:- Zn + HCl (dil.) —-> ZnCl2 + H2
Ans:- The gas which is used to extinguishes a burning candle that is CO2 (Carbon dioxide). The Metal compound ‘A’ is CaCO3 (Calcium Carbonate) because, When CaCO3 (Calcium Carbonate) reacts with the HCl (hydrochloric acid). Then it forms CaCl2 (Calcium Chloride).
CaCO3 (Calcium Carbonate) + HCl (hydrocholoric Acid) ——-> CaCl2 (Calcium Choloride) + CO2 + H2O
In Text Questions Page no. 25
Ans:- The Compound which releases H+ ions in Aqueous solution are known as Acidic Compounds.
A compound like HCl and HNO3 when dissolving in water then they release H+ ions in the Solution. That shows the Property of an Acid.
The Compounds like Alcohol and glucose, Although it contains H (hydrogen) atom they don’t release in their Aqueous form, that’s why they don’t show any acidic Property.
Hence dissociation or release of H+ ions in Aqueous solution will decide the acidic or non-acidic nature of any compound.
2. Why does an aqueous solution of acid conduct electricity?
Ans:- Acids release H+ ions (Charge particles) in Aqueous solution, and these charged particles help in the conduction of the Electricity.
3. Why does dry HCl gas not change the color of the dry litmus paper?
Ans:- Dry Hydrogen does not gives/releases H+ ions, And when H+ ions not released then HCl does not show any Acidic property, that’s why the color of litmus paper remains the same.
4. While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?
Ans:- It is recommended to add acid to water in a very slow manner and not water to acid because the process of adding water to Acid is highly Exothermic Process. This can cause the mixture to splash out and can burn the skin. Or this can also cause a huge amount of Explosion if directly water will be added to Concentrated Acid.
So, For safety purposes, it is always recommended to add Acid into the water not water into Acid.
5. How is the concentration of hydronium ions (H3O+) affected when a solution of an acid is diluted?
Ans:- When we add acid to water there will be a fixed amount of hydronium (H3O+) ions present in the fixed volume of solution. If we will dilute the solution hydronium ion (H3O+) per volume of solution decrease, this in-turn decreases Hydronium ions (H3O+) concentration in the solution.
6. How is the concentration of hydroxide ions (OH– ) affected when excess base is dissolved in a solution of sodium hydroxide?
When we dissolved base in sodium hydroxide solution then its hydroxide ions increase but it will reach saturation at some point. But After saturation point hydroxide ion concentration will not affect even after adding base further.
In-text questions/Answers Page Number 28 class 10, Chapter-2 (Acid Bases and Salts.)
Ans:- There is a very Important Rule that is not mentioned in your NCERT Book. “The pH of any solution is inversely proportional to the hydrogen ion concentration”.
It means that if the pH of any solution will be lower, then the Quantity/Concentration of H+ ions present in the solution will be higher.
So from the above data, it is proven that the Solution ‘A’ will have more H+ ions in Comparision with the Solution ‘B’.
Solution ‘A’ id Acidic in nature whereas, Solution ‘B’ is Basic in nature.
2. What effect does the concentration of H+(aq) ions have on the nature of the solution?
Ans:- In any Solution or Compound the H+ ions decides the Nature of the Substance/Solution. If the no. of H+ ions present in any solution will be Higher then the solution will be acidic in nature and if the, no. of H+ ions present in any solution is less and no. of OH- ions are higher then the solution will be Basic in nature.
3. Do basic solutions also have H+(aq) ions? If yes, then why are these basic?
Ans:- Yes, In some cases basic Solutions also have the H+ ions but the Concentration of OH- (Hydroxide) ions present in the solution is much higher than H+ ions.
And that’s why the solution is basic in nature. Because when the Concentration of H+ ions increases then the solution is acidic in nature. But when the concentration of H+ ions decreases and OH- ions Increases then the solution becomes basic in nature.
Ans:- Quick Lime, Slaked Lime, or Calcium carbonate are Metal Oxides and Metal Oxides are Basic in Nature. And when the pH of Soil goes below the 7, means when the soil goes acidic in nature then we apply all these Solutions to neutralize the Acidic effect in Soil.
In-text questions set 5 Page Number 34 Class 10th Chapter -2 (Acid Bases and Salts).
1. What is the common name of the compound CaOCl2?
Ans:- CaOCl2 (Calcium-Oxy-Chloride) is also known as Bleaching Powder.
2. Name the substance which on treatment with chlorine yields bleaching powder?
And:- Calcium Hydroxide (Ca(OH)2) which on treatment with chlorine yields bleaching powder.
3. Name the sodium compound which is used for softening hard water?
Ans:- ***Sodium carbonate[Na2CO3] is the compound that is used for softening hard water.
4. What will happen if a solution of sodium hydrocarbonate is heated? Give the equation of the reaction involved.
Ans:- When we heat Sodium Hydrogen Carbonate (NaHCO3), Sodium carbonate + water + carbon dioxide will produce.
NaHCO3 (on heating) ——> Na2CO3 + H2O + CO2
5. Write an equation to show the reaction between the Plaster of Paris and water?
Ans:- Here is the equation showing the reaction between Plaster of Paris(CaSO4.1/2H2O) and Water.
CaSO4.1/2H2O (Plaster of Paris) +3/2H2O → CaSO4.2H2O (Gypsum).
Exercise questions page Number 33
1. A solution turns red litmus blue, its pH is likely to be
(a)1 (b) 4 (c) 5 (d) 10
Ans:- (D). Because pH more than 7 (the solution considered as Basic in nature). And a Base only can change the red color litmus into Blue Color.
2. A 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) KCl
Ans:- (b). HCl (Hydrochloric Acid).
Because Eggshells are made up of Calcium Carbonate (CaCO3) and when CaCO3 reacts with the HCl then it produces CO2 which turns Lime water Milky.
Ans:- As you know, 10 ml of NaOH requires 8 mL of HCL, 20 ml of NaOH will require 8 x 2 = 16mL of HCl (Hydrochloric Acid). Hence (D) is the correct option.
4. Which one of the following types of medicines are used for treating indigestion?
(a) Antibiotic (b) Analgesic (c) Antacid (d) Antiseptic
Ans:- Indigestion is Caused by the Excess production of HCl (Hydrochloric acid) in our Stomach. And for the treatment of this problem we use ‘Antacids’.
7. Why does distilled water not conduct electricity, whereas rainwater does?
Ans:- Distilled Water does not contain any ionic Compound/Charge. that’s why it does not conduct any Electricity.
Whereas rainwater is the Mixtures of a lot of gases like Sulphur dioxide, Carbon Dioxide, Nitrogen Di/tri-oxide, these gases are acidic in nature and acids help in the Conduction of electricity.
That’s why rainwater conducts Electricity, whereas Distilled water does not do so.
8. Why do acids not show acidic behavior in the absence of water?
Ans:- The acidic behavior is shown by the acids because of the H+ ions only. And in the absence of water, the Acids do not produce H+ ions that’s why acidic behavior does not show by them in the Absence of water.
A pH value is 4, ‘B’ pH value is 1, ‘C’ pH value is 11, ‘D’ pH value is 7, and ‘E’ pH value is 9.
(a). ‘D’ is Neutral. Because the pH value is 7.
(b). ‘C’ is strongly Alkaline. Because the pH value of ‘C’ is 11.
(c). ‘B’ is Strongly acidic in nature because the pH value of ‘B’ is 1.
(d). ‘A’ is Weakly acidic in nature because the pH value of ‘A’ is 4.
(e). ‘E’ is weakly alkaline in nature because the pH value of ‘E’ is 9.
Ans:- In test-tube ‘A’ fizzing occur more vigorously because HCl is in the first test tube and HCl Is very strong acid if you’ll compare it with the CH3COOH (Acetic Acid).
The concentration of H+ ions will be higher in HCl. And when Magnesium reacts with HCl large amount of H2(g) will release. That’s why in the first test tube Fizzing will occur more Vigorously.
11. Fresh milk has a pH of 6. How do you think the pH will change as it turns into a curd? Explain your answer.
Ans:- The pH of the Milk will decrease, Because of the formation of lactic acid in milk. Lactic acid converts milk into curd.
Ans:- (a). He Slightly shifted the pH of the fresh milk from 6 to slightly alkaline to prevent milk from getting sour due to the formation of lactic acid into milk.
(b). Because the lactic acid produced here will first neutralize the pH then the pH is reduced to turn the milk to curd that’s why this milk will take a ling to set ass Curd.
13. The plaster of Paris should be stored in a moisture-proof container. Explain why?
Ans:- Plaster of Paris should be stored in a moisture-proof container because moisture can affect the plaster of Paris and convert it into a hard substance that is Gypsum.
CaSO4.1/2H2O (POP) + 1.5H2O —–> CaSO4.2H2O (Gypsum)
14. What is a neutralization reaction? Give two examples.
Ans:- This is a type of reaction in which acid and bases react with each other to produce salt and water.
Acid + base —-> Salt+ water (This type of reaction is known as Neutralisation reaction).
Examples of Neutralisation reactions are:- NaOH + HCl → NaCl + H2O, Mg(OH)2 (Magnesium Hydroxide) + H2CO3 (Carbonic Acid) → MgCO3 + 2H2O.
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