Acids and Alkalis part 1

Question 1

Describe what the main hazard symbols mean.

Answer 1

Corrosive: Causes severe skin burns and eye damage.

Irritant: Can cause redness or blistering upon skin contact.

Toxic: Can cause serious harm if ingested, inhaled, or absorbed.

Question 2

Describe the safety precautions that should be observed when handling different acids and alkalis.

Answer 2

Wear gloves, goggles, and a lab coat; handle chemicals in a well-ventilated area; and avoid direct contact with skin.

Question 3

Name the ions present in all acidic and all alkaline solutions.

Answer 3

Acids: Hydrogen ions (H⁺)
Alkalis: Hydroxide ions (OH⁻)

Question 4

State the pH values associated with acidic, alkaline, and neutral solutions.

Answer 4

Acidic: pH less than 7

Neutral: pH of 7

Alkaline: pH greater than 7

Question 5

Describe the effect of acids and alkalis on common indicators.

Answer 5

Litmus: Turns red in acid, blue in alkali
Phenolphthalein: Colorless in acid, pink in alkali
Methyl Orange: Red in acid, yellow in alkali

Question 6

Describe the relationship between hydrogen ion concentration and pH.

Answer 6

As hydrogen ion concentration increases, pH decreases, making the solution more acidic.

Question 7

Explain the link between pH and the concentration of ions in acids and alkalis.

Answer 7

The pH of a solution decreases as the concentration of hydrogen ions (H⁺) increases, and increases as the concentration of hydroxide ions (OH⁻) increases.

Question 8

Describe how a base reacts in a neutralisation reaction.

Answer 8

A base reacts with an acid, neutralizing it to produce a salt and water.

Question 8

Explain the difference between a dilute and concentrated solution (in terms of the amount of solute present).

Answer 8

Dilute: Contains a small amount of solute per unit volume.
Concentrated: Contains a large amount of solute per unit volume.

Question 9

Explain the difference between strong and weak acids (in terms of the degree of dissociation of the acid molecules).

Answer 9

Strong acids fully dissociate in water, releasing all H⁺ ions.
Weak acids only partially dissociate, releasing fewer H⁺ ions.

Question 10

Explain how the pH and reactivity of an acid depend on the concentration and the strength of the acid.

Answer 10

The pH is lower for strong acids and higher concentrations, making them more reactive than weaker or more dilute acids.

Question 11

Describe what happens when an acid reacts with a metal oxide.

Answer 11

The acid and metal oxide react to produce a salt and water.

Question 12

Write word equations for the reactions of acids and metal oxides.

Answer 12

Hydrochloric acid + copper oxide → copper chloride + water

Question 13

Write symbol equations for the reactions of acids and metal oxides.

Answer 13

2HCl+CuO→CuCl2+H 2O

Question 14

Explain what happens during a neutralisation reaction.

Answer 14

Hydrogen ions (H⁺) from the acid and hydroxide ions (OH⁻) from the base combine to form water, neutralizing the solution.

Question 15

Describe the steps involved in preparing a soluble salt from an acid and an insoluble reactant.

Answer 15

Add excess insoluble reactant to acid, filter out the excess, then evaporate the filtrate to crystallize the salt.

Question 16

Explain why an excess of insoluble reactant is used, the excess is removed, and only salt and water remain when preparing a soluble salt.

Answer 16

Excess reactant ensures all acid is neutralized.
Excess removal avoids contaminating the solution.
Salt and water are the only products left after filtering and evaporating the solution.