2.2.4 Purity and Formulations

• Match the type of substance with its description:

  Pure ↔️ Made entirely of one substance

  Impure ↔️ Contains unwanted substances
• What is the composition of a pure substance?

  One substance only
• What is the function of the melting point tube shown in the image?

  To contain the sample being tested for its melting point
• Match the substance with its composition:

  Pure substance ↔️ One type of atom or molecule

  Mixture ↔️ Two or more substances
• What is the purpose of the rubber ring shown in the image?

  To hold the sample in the melting point tube
• What is the key difference between pure substances and mixtures?

  Their composition
• What does purity in chemistry refer to?

  Desired substance without unwanted stuff
• What is an example of a mixture?

  Lemonade
• What kind of temperature change occurs when a pure substance melts?

  Sudden, at fixed point
• What is the name of the device shown in the image?

  Thermometer
• What is an example of an impure substance?

  Tap water
• What are the key components of the apparatus shown in the image and their functions?

  • Thermometer: Measures the temperature of the sample
  • Rubber ring: Holds the sample in the melting point tube
  • Melting point tube: Contains the sample being tested
  • Stirrer: Helps ensure even heating of the sample
  • Oil bath: Provides controlled heating of the sample
• What is the chemical definition of a pure substance?

  One type of molecule
• What is an example of an active ingredient in pain relievers?

  Paracetamol
• What is an example of a preservative used in food?

  Benzoic acid
• What are the key components of bread?

  Flour, yeast, water
• What is the purpose of the oil bath shown in the image?

  To heat the sample in the melting point tube
• How can the melting point of a solid sample be determined using the apparatus shown in the image?

  1. Place the solid sample in the melting point tube
  2. Secure the tube with the rubber ring
  3. Immerse the tube in the oil bath
  4. Slowly heat the oil bath
  5. Observe the temperature at which the sample starts to melt
  6. This temperature is the melting point of the sample
• What is the role of stabilizers in chemical formulations?

  Maintain consistency
• What category does bread fall under in the table?

  Food
• What is the role of sunscreen lotion in daily life?

  Protects skin from UV rays
• Match the ingredient type with its role:

  Stabilizers ↔️ Maintain product consistency

  Preservatives ↔️ Prevent spoilage
• What are the key components of paracetamol tablets?

  Paracetamol, binders
• What is one common method to determine the purity of a substance?

  Measuring melting point