← Wood Technology & Design 1-4
Definitions, pH scale, strength and concentration, indicators, and titrations.
Acids and bases are fundamental concepts in chemistry that describe the properties of substances that can donate or accept electrons. Understanding acids and bases is crucial for many chemical reactions, including neutralization, precipitation, and acid-base titrations.
The pH scale is a measure of the concentration of hydrogen ions (H+) in a solution. It ranges from 0 to 14, with 7 being neutral. A pH below 7 is acidic, while a pH above 7 is basic. The pH scale is logarithmic, meaning that each whole number difference represents a tenfold change in acidity.
The strength of an acid or base refers to its ability to donate or accept hydrogen ions. Concentration, on the other hand, refers to the amount of substance present in a given volume. A strong acid or base is one that completely dissociates in water, while a weak acid or base only partially dissociates.
Indicators are substances that change color in response to changes in pH. They can be used to determine the pH of a solution and indicate whether it is acidic, basic, or neutral. Examples of indicators include litmus paper, phenolphthalein, and bromothymol blue.
A titration is a laboratory procedure used to determine the concentration of an acid or base. It involves slowly adding a known solution of an acid or base to another solution until the reaction is complete. The endpoint of the titration is indicated by an indicator, and the amount of substance required to reach this point can be used to calculate the original concentration.
A neutralization reaction occurs when an acid and a base react to form a salt and water. The reaction is complete when the acid and base have completely reacted, resulting in a neutral solution with a pH of 7. Examples of neutralization reactions include the reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH) to form sodium chloride (NaCl) and water.
Examples of common acids include hydrochloric acid (HCl), sulfuric acid (H2SO4), and acetic acid (CH3COOH). Examples of common bases include sodium hydroxide (NaOH), potassium hydroxide (KOH), and ammonia (NH3).
Acids and bases have many real-world applications, including the production of soap and detergents, the manufacture of paper, and the treatment of wastewater. They are also used in food processing, pharmaceuticals, and medical research.
One common misconception is that acids and bases are always harmful or dangerous. However, many everyday substances are actually acids or bases, such as stomach acid and baking soda. Another misconception is that all acids are corrosive or damaging to skin and surfaces.
When working with acids and bases, it is important to follow proper safety precautions to avoid accidents and injuries. This includes wearing protective clothing, such as gloves and goggles, and handling substances in a well-ventilated area away from heat sources.
What is a characteristic of acids?
What is the strength of an acid or base?
What is the pH scale?
What is an indicator used for?
What is a neutralization reaction?
What is the pH of a neutral substance?
What happens when an acid and a base react?
What is the Henderson-Hasselbalch equation used for?
What is the purpose of a titration?
What is the difference between a strong and weak acid?
What is the pH of a solution that contains 0.1 M HCl and 0.2 M NaOH? (2 marks)
A certain acid has a pH of 3. What is its concentration? (2 marks)
What is the pH of a solution that contains 0.5 M HNO3 and 0.1 M KOH? (2 marks)
A certain base has a pH of 9. What is its concentration? (2 marks)
What is the pH of a solution that contains 0.1 M HCl and 0.5 M NaOH? (2 marks)
Discuss the importance of acids and bases in everyday life. (20 marks)
Describe the differences between strong and weak acids and bases. (20 marks)