Chemistry: Acids, Bases and Salts

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Questions and Answers

What is the balanced chemical equation for the reaction between sodium hydroxide and zinc?

The balanced equation is 2NaOH(aq) + Zn(s) → Na2ZnO2(s) + H2(g).

What form of gas is produced when sodium carbonate reacts with dilute hydrochloric acid?

Carbon dioxide (CO2) gas is produced during the reaction.

How does the reaction of sodium bicarbonate with dilute hydrochloric acid differ from that of sodium carbonate?

Both produce carbon dioxide, but the reaction rate can differ; sodium bicarbonate reacts more slowly than sodium carbonate.

What observation can indicate the presence of carbon dioxide when passed through lime water?

Lime water turns milky or cloudy in the presence of carbon dioxide. Signup and view all the answers

Why can't all metals react in a similar way with sodium hydroxide as zinc does?

Not all metals can displace hydrogen from sodium hydroxide; it depends on their reactivity. Signup and view all the answers

What odour changes were observed when dilute vanilla essence was mixed with dilute HCl and NaOH?

The odour changes indicate that vanilla can act as an olfactory indicator, showing different scents when mixed with acids and bases. Signup and view all the answers

What physical change was observed on the surface of zinc granules when they reacted with dilute sulphuric acid?

The surface of the zinc granules became covered in bubbles, indicating the production of hydrogen gas. Signup and view all the answers

Explain why bubbles are formed when the gas evolved from zinc reaction with acid is passed through soap solution.

Bubbles form because the hydrogen gas gets trapped in the soap solution, creating foam. Signup and view all the answers

What observation is made when a burning candle is brought near the gas-filled bubbles from the reaction with zinc?

The bubbles produce a 'pop' sound and may ignite, indicating the presence of hydrogen gas. Signup and view all the answers

What general equation summarizes the reaction of an acid with a metal?

The equation is: Acid + Metal → Salt + Hydrogen gas. Signup and view all the answers

When testing clove oil, what observations would indicate it could also serve as an olfactory indicator?

Changes in the scent of clove oil when mixed with dilute HCl and NaOH would indicate its use as an olfactory indicator. Signup and view all the answers

What is formed when zinc reacts with sodium hydroxide solution upon warming?

When warmed with sodium hydroxide, zinc may produce hydrogen gas and a zincate ion in solution. Signup and view all the answers

Based on observations, which substances can be classified as olfactory indicators?

Vanilla and clove oil can be classified as olfactory indicators based on their scent changes in different pH solutions. Signup and view all the answers

What defines a family of salts?

A family of salts is defined by having the same positive or negative radicals, such as NaCl and Na2SO4 both being sodium salts. Signup and view all the answers

How many families of salts can be identified from the given salts?

The number of families can be determined by analyzing the composition of the salts listed. Signup and view all the answers

What is the significance of pH in classifying salts?

The pH of salts helps classify them as acidic, basic, or neutral based on their reaction with litmus and their solubility. Signup and view all the answers

Which salts might be classified as acidic based on their pH?

Salts with a pH value less than 7, formed from strong acids and weak bases, are classified as acidic. Signup and view all the answers

What is sodium chloride and how is it formed?

Sodium chloride, also known as table salt, is formed by the combination of hydrochloric acid and sodium hydroxide. Signup and view all the answers

How are rock salt deposits formed?

Rock salt deposits are formed from the evaporation of seawater in ancient oceans, leaving behind large crystals. Signup and view all the answers

What were the historical implications of sodium chloride during India's struggle for freedom?

Sodium chloride symbolized resistance in the struggle for Indian independence, notably during Mahatma Gandhi's Dandi March. Signup and view all the answers

What role does litmus paper play in determining the nature of salt solutions?

Litmus paper is used to observe the acidity or basicity of salt solutions, indicating their pH level. Signup and view all the answers

What can you infer about the ideal soil pH for plant growth in your region based on the activity performed?

The ideal soil pH for plant growth in my region is typically around neutral, between 6.0 and 7.0, as most plants thrive in this range. Signup and view all the answers

How does hydrochloric acid in our stomach aid in digestion without harming the stomach lining?

Hydrochloric acid facilitates the breakdown of food and activates digestive enzymes, while the stomach's mucous membrane protects it from the acid. Signup and view all the answers

What role do antacids play during episodes of indigestion?

Antacids neutralize excess hydrochloric acid in the stomach, alleviating pain and discomfort associated with indigestion. Signup and view all the answers

At what pH level does tooth decay begin, and what causes this condition?

Tooth decay begins when the pH of the mouth drops below 5.5, primarily caused by acid production from bacteria after sugar and food remnants are left in the mouth. Signup and view all the answers

Why are toothpastes usually basic, and how do they help prevent tooth decay?

Toothpastes are usually basic to neutralize acids in the mouth, thus preventing tooth enamel corrosion and decay. Signup and view all the answers

What kind of acid is injected by the stinging hairs of nettle leaves, and what is its effect?

The stinging hairs of nettle leaves inject methanoic acid, which causes burning pain upon contact. Signup and view all the answers

What traditional remedy is employed to alleviate pain from nettle stings, and how does it work?

Rubbing the affected area with dock plant leaves is a traditional remedy that helps neutralize the methanoic acid from the sting. Signup and view all the answers

What effect does cleaning the mouth after eating have on oral health?

Cleaning the mouth after eating helps prevent the buildup of acids, thus maintaining a suitable pH and protecting against tooth decay. Signup and view all the answers

What happens to the color of copper sulphate when it is heated?

It turns white after heating. Signup and view all the answers

Where do the water droplets in the boiling tube come from during the copper sulphate heating experiment?

The water droplets come from the moisture in the air or the environment. Signup and view all the answers

What observation is made when water is added back to the heated copper sulphate?

The blue color of copper sulphate is restored. Signup and view all the answers

What is the chemical formula for hydrated copper sulphate?

The formula is Cu SO4.5H2O. Signup and view all the answers

How many water molecules are present in one formula unit of gypsum?

There are two water molecules in one formula unit of gypsum. Signup and view all the answers

What is produced when gypsum is heated at 373 K?

It produces calcium sulphate hemihydrate, also known as Plaster of Paris. Signup and view all the answers

What is the importance of water of crystallization in salts like copper sulphate?

Water of crystallization affects the physical properties and color of the salts. Signup and view all the answers

Why is Plaster of Paris used in medicine?

It is used to support fractured bones in the correct position. Signup and view all the answers

In which test tube, A or B, will the fizzing occur more vigorously when magnesium ribbon is added to HCl or acetic acid and why?

Fizzing will occur more vigorously in test tube A with hydrochloric acid because HCl is a stronger acid than acetic acid, providing more hydrogen ions for the reaction. Signup and view all the answers

How does the pH of fresh milk change as it turns into curd and why?

The pH of fresh milk decreases (becomes more acidic) as it turns into curd due to the production of lactic acid during fermentation. Signup and view all the answers

Why does a milkman add a small amount of baking soda to fresh milk?

Baking soda is added to shift the pH of fresh milk from 6 to slightly alkaline to enhance its shelf life and prevent spoilage. Signup and view all the answers

Why does milk take a long time to set as curd when baking soda is added?

Milk takes longer to set as curd because the alkaline environment from baking soda inhibits the activity of lactic acid bacteria needed for curdling. Signup and view all the answers

Why should plaster of Paris be stored in a moisture-proof container?

Plaster of Paris should be stored in a moisture-proof container because it reacts with water to form gypsum, which would ruin its effectiveness. Signup and view all the answers

What is a neutralization reaction? Provide two examples.

A neutralization reaction is a chemical reaction between an acid and a base that produces salt and water. Examples include the reaction of hydrochloric acid with sodium hydroxide, and the reaction of acetic acid with sodium bicarbonate. Signup and view all the answers

List two important uses of washing soda and baking soda.

Washing soda is commonly used for cleaning and as a water softener, while baking soda is used in baking and as an antacid. Signup and view all the answers

What happens when dilute sulphuric acid mixes with sodium bicarbonate in a soda-acid fire extinguisher setup?

When dilute sulphuric acid mixes with sodium bicarbonate, carbon dioxide is produced, which can be directed onto a burning candle to extinguish the flame. Signup and view all the answers

Flashcards

Acid-Metal Reaction

A chemical reaction between an acid and a metal that produces hydrogen gas and a salt.

Hydrogen Gas

A colorless, odorless, and highly flammable gas produced when an acid reacts with a metal.