Acids & bases

• What does the pH scale measure?

  How acidic or alkaline a solution is
• What is the pH range of the scale?

  0 to 14
• What pH value indicates a neutral solution?

  7
• What is the pH of stomach acid?

  Around 2
• What is the pH of acid rain?

  Around 4
• What is the pH of washing up liquid?

  Around 9
• What is the pH of bleach?

  Around 12
• What are indicators used for in measuring pH?

  They change color depending on the pH
• What is a wide range indicator?

  Changes color across a wide range of pH
• What colors does the universal indicator show at low pH?

  Deep red
• What colors does the universal indicator show at high pH?

  Bluey purple
• How does a pH probe measure pH?

  By electronically measuring the pH
• Why is a pH probe more reliable than an indicator?

  It removes human judgment from measurement
• How is an acid defined in terms of pH?

  pH less than 7
• What do acids release in water?

  Hydrogen ions
• How is a base defined in terms of pH?

  pH greater than 7
• What is an alkali?

  A base soluble in water
• What ions do alkalis form in water?

  Hydroxide ions (OH⁻)
• What happens in a neutralization reaction?

  Produces salt and water
• What is the reaction between hydrochloric acid and sodium hydroxide?

  Produces sodium chloride and water
• What do H⁺ and OH⁻ ions combine to form?

  Water (H₂O)
• What is the pH of the products in a neutralization reaction?

  7
• What are some common acids and bases?

  Common acids:

  • Hydrochloric acid
  • Sulfuric acid
  • Nitric acid

  
  

  Common bases:

  • Sodium hydroxide
  • Calcium carbonate
• Why is it useful to learn common acids and bases?

  They frequently appear in coursework
• What are the key characteristics of acids and bases?

  • Acids: pH < 7, release H⁺ ions
  • Bases: pH > 7, release OH⁻ ions
  • Alkalis: soluble bases in water