Chapter 4 Chem

• What is the main topic discussed in this material?

  Chemical Changes
• What are the two main types of substances discussed in this topic?

  Acids and Bases
• Why are acids and bases important in chemistry?

  They are fundamental to understanding the concept of pH.
• What is the range of the pH scale?

  0 to 14
• What does the pH scale measure?

  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?

  7
• How is the pH scale visually represented?

  • pH scale ranges from 0 to 14
  • Acids are on the left (0-6)
  • Neutral is at 7
  • Alkalis are on the right (8-14)
• What is an indicator in the context of pH measurement?

  A dye that changes color depending on the pH level.
• What are wide-range indicators used for?

  Estimating the pH of a solution over a broad range.
• How does a pH probe measure pH?

  It provides a numerical value on a digital display.
• What happens during the neutralization of acids and bases?

  They neutralize each other to form salt and water.
• What is the pH of an aqueous solution formed by an acid?

  Less than 7
• What ions do acids form in water?

  H+ ions
• What is a base?

  A substance that reacts with an acid to form a salt.
• What is an alkali?

  A base that dissolves in water to form a solution with a pH greater than 7.
• What is the general equation for the neutralization reaction?

  acid + base → salt + water
• How can neutralization be represented in terms of ions?

  H+ + OH– → H2O
• What is the pH of the products formed when an acid neutralizes a base?

  The products have a pH of 7.
• What is the pH of human skin?

  5.5
• What happens when an acid is mixed with an alkali?

  Hydrogen ions react with hydroxide ions to make water, and the leftover components form a salt.
• What is the purpose of titrations?

  To find out the exact volume of acid needed to neutralize a known volume of alkali.
• What can you determine from titration data?

  The concentration of the acid or alkali.
• What is the first step in performing a titration?

  Use a pipette to add a known volume of alkali to a conical flask.
• Why should you fill the burette below eye level?

  To avoid looking up if acid spills.
• What should you do as you approach the end-point of a titration?

  Add acid slowly and swirl the flask regularly.
• What indicates that all the alkali has been neutralized during a titration?

  The indicator changes color.
• How do you calculate the volume of acid used in a titration?

  Subtract the initial volume from the final volume in the burette.
• What apparatus is used in a titration?

  • Pipette
  • Burette
  • Conical flask
  • Indicator
• What does a pipette do?

  A pipette measures a specific volume of solution.
• What is the function of a burette?

  A burette measures different volumes and allows drop-by-drop addition of solution.
• Why should titrations be repeated?

  To increase accuracy and identify anomalous results.
• What is the purpose of a rough titration?

  To get an approximate idea of when the solution changes color.
• How do you calculate the mean volume from titration results?

  By averaging the consistent readings, ignoring anomalous results.
• What is the advantage of using single indicators in titrations?

  They provide a sudden color change at the end point.
• What color does phenolphthalein turn in alkaline conditions?

  Pink
• What color does litmus turn in acidic solutions?

  Red
• What color does methyl orange turn in alkaline solutions?

  Yellow
• Why is accuracy important in titrations?

  To ensure reliable and valid results.