acids,bases and salts

Question 1

What are the properties of acids?

Answer 1

• Sour taste
• pH < 7
• Turn blue litmus paper red
• React with bases to produce salt and water
• React with metals above hydrogen to produce salt and hydrogen
• React with carbonates to produce salt, water, and carbon dioxide
• React with ammonia to produce fertilizers

These properties are key for identifying acids in various contexts.

Question 2

What are the properties of alkalis (bases)?

Answer 2

• Bitter taste
• Feel slippery (soapy)
• pH > 7
• Turn red litmus paper blue
• React with acids to produce salt and water
• React with ammonium salts to produce ammonia gas
• React with metal cations forming precipitate
• React with oil/fat to produce soap

Understanding these properties helps in distinguishing bases from acids.

Question 3

Define an Arrhenius acid.

Answer 3

Any substance that releases H+ ions when dissolved in water

Example: HCl (aq) → H+ (aq) + Cl- (aq)

Question 4

Define an Arrhenius base.

Answer 4

Any substance that releases OH- ions when dissolved in water

Example: NaOH (aq) → Na+ (aq) + OH- (aq)

Question 5

What is the difference between strong acids and weak acids?

Answer 5

• Strong acids ionize completely in water
• Weak acids ionize partially in water

Strong acids include HCl, HNO3, and H2SO4, while weak acids include acetic acid.

Question 6

What is the pH scale range?

Answer 6

Runs between 0 and 14

pH values below 7 indicate acidity, while values above 7 indicate basicity.

Question 7

What is a universal indicator?

Answer 7

A mixture of several indicators that gives different colours at different pH numbers

It is used to show how much acidic or alkaline a solution is.

Question 8

What happens when acids react with metals?

Answer 8

Acid + metal → salt + hydrogen

Example: 2HCl + Zn → ZnCl2 + H2

Question 9

What is a neutralization reaction?

Answer 9

The reaction between acid and base to form salt and water

It involves the combination of H+ with OH- to form water.

Question 10

How do you identify a strong acid using a universal indicator?

Answer 10

Add Universal Indicator; strong acid turns UI red

This indicates a strong acid’s high concentration of H+ ions.

Question 11

What is the role of sulfuric acid (H2SO4)?

Answer 11

Used in various applications including batteries, fertilizers, and metal processing

It is one of the most commonly used industrial acids.

Question 12

What is the significance of soil acidity?

Answer 12

Plants do not grow well in acidic soil; they prefer pH around 7

Testing and adjusting soil pH is crucial for agricultural practices.

Question 13

What is the reaction of baking soda with acetic acid?

Answer 13

NaHCO3 + HC2H3O2 → NaC2H3O2 + H2O + CO2 (g)

This reaction produces carbon dioxide gas, which helps in baking.

Question 14

What are the dangers of acid rain on limestone buildings?

Answer 14

Acid rain reacts with limestone (CaCO3) and wears it away

This leads to structural damage in buildings made from limestone.

Question 15

What is the formula for calculating pH?

Answer 15

pH = -log[H+]

This formula indicates that pH is inversely proportional to the concentration of H+ ions.

Question 16

What is a common antacid and its function?

Answer 16

Mg(OH)2 (milk of magnesia); neutralizes excess stomach acid

Antacids are used to relieve indigestion and heartburn.

Question 17

What are the physical properties of acids?

Answer 17

• Sour taste
• pH < 7
• Turn blue litmus paper red

These properties help in identifying acids in various contexts.

Question 18

What are the chemical properties of bases?

Answer 18

• React with acids to produce salt and water
• React with ammonium salts to produce ammonia gas

Understanding these chemical properties is essential for various chemical reactions.