CHAPTER 2: ACIDS, BASES AND SALTS

Explanation:

To identify the contents of each test tube using only red litmus paper, follow these steps:

1. Label each test tube with the type of solution it contains.

2. Take a piece of red litmus paper and dip it into the first test tube containing distilled water. If the litmus paper remains red, it indicates that the distilled water is neutral and neither acidic nor basic.

3. Next, take a fresh piece of red litmus paper and dip it into the second test tube containing the acidic solution. If the litmus paper turns blue, it indicates that the solution is acidic. This is because acids react with the red litmus paper to turn it blue.

4. Finally, take another fresh piece of red litmus paper and dip it into the third test tube containing the basic solution. If the litmus paper turns blue, it indicates that the solution is basic. This is because bases do not react with red litmus paper, so it retains their red color.

By following these steps, you can identify the contents of each test tube using only red litmus paper. The litmus paper will turn blue in the presence of an acidic solution but will remain red in the presence of neutral or basic solutions. It is important to note that if blue litmus paper had been available instead, it would have turned red in the presence of an acidic solution and remained blue in the presence of a basic solution.

Explanation:

Curd and other sour substances should not be kept in brass and copper vessels because these materials react with acids to produce toxic compounds that can be harmful to human health. Brass is an alloy composed mainly of copper and zinc, while copper is a pure metal. Both of these metals are reactive with acidic substances, such as curd, vinegar, or citrus juices, and can leach copper and zinc ions into the food or drink.

When curd or other sour substances are kept in brass or copper vessels, the acidic nature of the food or drink causes the copper and zinc to dissolve and mix with the contents. This can lead to the formation of toxic compounds, such as copper sulfate, which can cause nausea, vomiting, and diarrhea if ingested. Additionally, long-term exposure to high levels of copper in the diet can lead to liver and kidney damage.

Explanation:

When an acid reacts with any substance, tar, and hydrogen gas are formed.    

Metal + Acid —> Salt + Hydrogen gas

Explanation:

As the substance conflation released is Calcium Chloride, the gas evolved also CO2. Hence,  substance A should be Calcium Carbonate. Hence, the response between Calcium Carbonate and HCl is 

Explanation:

The presence of H+ ions in water determines whether a substance is acidic or non-acidic. Acids are chemicals that, when combined with water, produce hydrogen ions.  Certain chemicals have an acidic character when they disconnect in waterless results, performing in the conformation of hydrogen ions( acids like HCl, and HNO3). 

Although composites analogous to glucose or alcohol include hydrogen, they don't parade acidic parcels. The hydrogen in them,  still, won't separate like the hydrogen in acids. When dissolved in water, they won't separate to form hydrogen ions.

Explanation:

An aqueous solution of acid conducts electricity because it contains ions that can move freely in the solution and carry an electric charge. When an acid dissolves in water, it dissociates into its constituent ions, which can carry an electric current.

Explanation:

HCl does not exhibit acidic behavior since it does not produce Hydrogen ions, and the colour of the litmus paper remains unaltered after reacting with HCl gas.

Explanation:

 It is advised that when diluting an acid, the acid be added to water rather than the water being added to the acid because adding water to a concentrated acid generates a significant amount of heat, which can result in an explosion and acid burns on the face, clothing, and body parts. As a consequence, combining acid and water is safe, while combining acid and vinegar is not.

Explanation:

The concentration of hydronium ions (H3O+) drops as an acid solution is diluted. This is because the dilution process involves adding more solvent (usually water) to the solution, which increases its volume and decreases its concentration of solute (the acid). The number of hydronium ions present in the solution remains the same, but they are now distributed in a larger volume of solution, resulting in a lower concentration of hydronium ions.

Explanation:

When the extra base is dissolved in a solution of sodium hydroxide, the concentration of hydroxide ions (OH-) increases (NaOH). This is because the excess base reacts with the sodium hydroxide to produce more hydroxide ions in the solution.

Explanation:

The solution with a pH of 6 has a higher hydrogen ion concentration than the solution with a pH of 8. This is because pH is a logarithmic scale that measures the concentration of hydrogen ions (H+) in a solution. The concentration of hydrogen ions increases as the pH value lowers.

Solution A has a pH of 6, whereas Solution B has a pH of 8. This is due to the fact that a pH of 7 is regarded as neutral, and any pH number less than 7 is considered acidic, while any pH value more than 7 is considered basic or alkaline. As a result, solution A with a pH of 6 is acidic, but solution B with a pH of 8 is basic since it exceeds 7.

Explanation:

The concentration of hydrogen ions in the solution dictates its composition. When the concentration of hydrogen ions rises, the solution becomes acidic; when it falls, the solution becomes basic.

Explanation:

H+ ions are present in basic solutions, although hydroxide ions are more prevalent. As a result, Hydroxide ions make the solution basic.

Explanation:

If the soil is acidic (PH less than 7), quick lime (calcium oxide), slaked lime (calcium hydroxide), or chalk should be used to treat it (calcium carbonate).

Explanation:

Bleaching powder is the popular name for the chemical CaOCl2.

Explanation:

Calcium hydroxide is the material that, when treated with chlorine, produces bleaching powder.

Explanation:

The ingredient used to soften hard water is sodium carbonate.

Explanation:

Heating sodium hydro carbonate produces sodium carbonate, which emits carbon dioxide gas.

Explanation:

The chemical equation for the reaction between Plaster of Paris and water is

CaSO4.1/2H2O + 3/2H2O → CaSO4.2H2O

Explanation:

The answer is 10 because the litmus paper becomes blue when the solution reacts with a basic solution (PH more than 7).

Explanation:

The answer is HCl, Eggshells contain calcium carbonate, which when combined with HCl releases CO2 gas, turning lime water milky.

CaCO3 + 2HCl → CaCl2 + H2O + CO2

Explanation:

An answer is an option (d) 16 mL because 10 ml of NaOH requires 8 mL of HCL, and 20 ml of NaOH requires 8 x 2 = 16 mL of HCl.

Explanation:

The answer is (c) Antacid, 

An excess of acid in the stomach causes indigestion. Antacids are anti-dyspepsia drugs.

Explanation:

(a) Dilute sulphuric acid reacts with zinc granules.

=> Dilute sulphuric acid + zinc → Zinc Sulphate + Hydrogen Gas

=> H2SO4(aq) + Zn → ZnSO4(aq) + H2(g)

(b) Dilute hydrochloric acid reacts with magnesium ribbon.

=> Dilute Hydrochloric + Magnesium → Magnesium Chloride + Hydrogen Gas

=> 2HCl(aq) + Mg → MgCl2(aq) + H2(g)

(c) Dilute sulphuric acid reacts with aluminium powder.

=> Dilute Sulphuric Acid + Aluminium → Aluminium Sulphate + Hydrogen Gas

=> 3H2SO4(aq) + 2Al(s) → Al2(SO4)3(aq) + 3H2(g)

(d) Dilute hydrochloric acid reacts with iron filings.

=> Dilute Hydrochloric Acid + Iron → Ferrous Chloride + Hydrogen Gas

=> 6HCl(aq) + 3Fe(s) → 3FeCl2(aq) + 3H2(g)

Explanation:

To demonstrate why hydrogen-containing substances such as alcohol and glucose are not classified as acids, you can conduct a simple experiment using litmus paper. Litmus paper is a commonly used pH indicator that changes color in the presence of an acid or a base.

Here are the steps for the experiment:

1. Gather the materials: You will need litmus paper, alcohol (e.g. ethanol), glucose solution, and water.

2. Dip a piece of litmus paper into water and observe its color. The color of the litmus paper should remain the same, indicating that the water is neutral.

3. Dip a piece of litmus paper into the alcohol and observe its color. If the alcohol is not acidic, the color of the litmus paper should remain the same as it was with water.

4. Repeat step 3 with the glucose solution.

5. Compare the results of the two tests. If the color of the litmus paper did not change for both the alcohol and glucose solution, it indicates that they are not acidic.

Alternatively, you could use a pH meter to measure the pH of the alcohol and glucose solution. If their pH values are close to 7 (neutral), it confirms that they are not acidic.

Explanation:

1. Ionic compounds are not present in distilled water.
2. Rainwater, on the other hand, contains far more chemicals.
   

3. Rainfall contains dissolved acidic gases, such as carbon dioxide from the atmosphere, which results in the formation of carbonic acid. This indicates it contains hydrogen ions as well as carbonate ions. As a result, raindrops may conduct electricity in the presence of acids.

Explanation:

Because of the presence of hydrogen ions, acids display acidic behavior. Acids must contain water in order to be acidic because hydrogen ions can only be generated in the presence of water.

Explanation:

In increasing order of hydrogen ion concentration,

pH 11(C) < pH 9(E) < pH 7 (D) <  pH 4 (A) < pH 1 (B)

PH11 – Strongly alkaline

pH9 – Weakly alkaline

PH7 – Neutral

pH4 – Weakly acidic

pH1 – Strongly acidic

Explanation:

Acetic is a mild acid, whereas HCl is a strong acid. The creation of hydrogen gas as a result of the acid's interaction with the magnesium ribbon causes fizzing. Since HCl is a very powerful acid, there is a lot of hydrogen gas liberation from test tube A. As a result, greater fizzing occurs in test tube A.

Explanation:

As fresh milk turns into curd, the pH will decrease, becoming more acidic. This is because curd is produced through the process of acidification, where lactic acid bacteria ferment the lactose in milk, producing lactic acid as a byproduct.

The presence of lactic acid in curd lowers its pH, making it more acidic than fresh milk. The pH of curd typically ranges from 4 to 5, depending on the specific method used to produce it and the type of milk used.

The decrease in pH during the curdling process is due to the production of lactic acid by the bacteria. Lactic acid is a weak acid that dissociates partially in the water, producing H+ ions. These H+ ions contribute to the overall acidity of the solution, lowering its pH.

Overall, the pH of fresh milk will decrease as it turns into curd due to the production of lactic acid during the curdling process. This decrease in pH is an important factor in the production of curd, as it helps to create the desired texture and flavor of the final product.

Explanation:

(a) He elevated the pH of fresh milk from 6 to slightly alkaline to avoid the milk from becoming sour owing to lactic acid production.

(b) It takes a long time for this milk to set into curd since the lactic acid generated here first neutralizes the pH before decreasing it to turn the milk into curd.

Explanation:

Plaster of Paris is a versatile material that has numerous applications in art, construction, and medicine. It is made by heating gypsum at high temperatures and then grinding it into a fine powder. When mixed with water, it quickly hardens and sets to form a solid structure. However, the plaster of Paris is highly reactive with water, and even small amounts of moisture can cause it to undergo a chemical reaction called hydration. This reaction can reduce the effectiveness of the plaster and render it unusable, which is why it is crucial to store it in a moisture-proof container.

When the plaster of Paris is exposed to moisture, it begins to absorb water and undergo a chemical reaction that converts it into gypsum. This reaction produces heat and releases water vapor, which can cause the plaster to harden prematurely and lose its strength. Moisture can also cause the plaster to clump together, making it difficult to mix and apply. By storing the plaster of Paris in a moisture-proof container, you can prevent it from coming into contact with moisture and ensure that it remains dry and powdery until you are ready to use it. Airtight containers made of plastic, glass, or metal are ideal for storing plaster in Paris because they prevent air and moisture from entering the container. It is also important to store the plaster in a cool, dry place away from direct sunlight and heat sources to further reduce the risk of moisture absorption.

Explanation:

A neutralization reaction is a chemical reaction that occurs when an acid and a base react with each other to form a salt and water. In this reaction, the acidic and basic properties of the reactants cancel each other out, resulting in a neutral product.

Here are two examples of neutralization reactions:

1. Hydrochloric acid (HCl) and sodium hydroxide (NaOH) reaction:

HCl + NaOH → NaCl + H2O

     2.  Sulfuric acid (H2SO4) and potassium hydroxide (KOH) reaction:

H2SO4 + 2KOH → K2SO4 + 2H2O

Explanation:

Washing soda and baking soda are both useful chemicals that have a wide range of applications in different industries and households. Here are two important uses of each of these chemicals:

Washing soda (Sodium Carbonate):

1. Laundry detergent: Washing soda is commonly used as a laundry detergent and stain remover due to its ability to soften water and remove tough stains. It is an effective cleaning agent that helps to break down and remove dirt, grease, and other stains from fabrics.

2. Glass manufacturing: Washing soda is also used in the production of glass as it helps to reduce the melting point of silica, a key ingredient in glass production. This makes the process more energy-efficient and reduces the cost of glass production.

Baking soda (Sodium Bicarbonate):

1. Baking: Baking soda is a key ingredient in baking as it reacts with acidic components in the recipe (like vinegar or lemon juice) to produce carbon dioxide gas, which helps to make cakes and other baked goods rise.

2. Cleaning: Baking soda is also a versatile cleaning agent that can be used to clean and deodorize various surfaces in the household. It can be used to clean kitchen countertops, sinks, and ovens, and even as a natural deodorizer for carpets, upholstery, and clothes.