Acids and bases

• What is the pH scale a measure of?


  How acidic or alkaline a solution is
• What does a lower pH indicate about a solution?


  The solution is more acidic
• What does a higher pH indicate about a solution?


  The solution is more alkaline
• What is the pH of a neutral substance like pure water?

  1. 7
• What are the ranges of the pH scale?


  • 0 to 14
  • Acids: pH < 7
  • Neutral: pH = 7
  • Alkaline: pH > 7
• What is an indicator in the context of pH testing?


  A substance that changes colour based on pH
• What are universal indicators?


  A mixture of dyes that measure pH across a range
• How does a pH probe work?


  It measures pH electronically and displays it digitally
• What is the pH of a solution formed by an acid?


  Less than 7
• What is the pH of a base?


  Greater than 7
• What ions do alkalis form in water?


  OH⁻ ions
• What is the reaction between acids and bases called?

  Neutralisation
• What is the general equation for neutralisation?


  acid + base → salt + water
• What happens to the pH when an acid neutralises a base?


  The products have a pH of 7
• How can an indicator be used in a neutralisation reaction?


  To show that the reaction is complete
• What technique can be used to calculate the concentration of an acid or alkali?

  Titration
• Why is pH important in chemistry?


  It is crucial for various chemical processes in our bodies
• What is the pH of human skin?


  1. 5
• If a student uses universal indicator to test lemon juice, what colour would you expect the indicator to turn?


  Red or orange
• If the pH of an unknown solution is found to be 8, is the solution acidic or alkaline?


  Alkaline
• What is the pH scale range for measuring acidity and alkalinity?


  0 to 14
• What does a pH of 7 indicate about a solution?


  It is neutral, like pure water
• What is the purpose of chemical dyes in measuring pH?


  They change color depending on pH
• What is a universal indicator?


  A wide range indicator that changes color depending on pH
• How does a pH probe work?


  It electronically measures pH by dipping the probe into a solution
• What is the definition of an acid?

  Any substance that forms an aqueous solution with a pH less than 7
• What do acids release in water?

  H+ ions
• What is the definition of a base?


  Any substance with a pH greater than 7
• What are alkalis?


  A subgroup of bases that are soluble in water
• What do bases form in water?


  OH- ions (hydroxide ions)
• What is the neutralization reaction formula?


  • Acid + Base → Salt + Water
  • Example: HCl + NaOH → NaCl + H₂O
  • H+ + OH- → H₂O
• What is the pH of a neutral solution?


  7
• What is hydrochloric acid's chemical formula?


  HCl
• What is the chemical formula for sulfuric acid?


  H₂SO₄
• What is the chemical formula for nitric acid?


  HNO₃
• What is the chemical formula for sodium hydroxide?


  NaOH
• What is the chemical formula for calcium carbonate?


  CaCO₃
• What are common acids and their formulas?

  • Hydrochloric acid - HCl
  • Sulfuric acid - H₂SO₄
  • Nitric acid - HNO₃
• What are common bases and their formulas?

  • Sodium hydroxide - NaOH
  • Calcium carbonate - CaCO₃