C8 - chemical analysis

• How is purity defined in chemistry compared to everyday use?

  Purity is defined differently in chemistry.
• What does the melting point indicate about a substance?

  The melting point indicates the purity of a substance.
• What are formulations in chemistry?

  Formulations are mixtures with exact amounts of components.
• Why are formulations important in chemistry?

  They ensure products meet specific properties.
• How do additives affect formulations?

  Additives change physical and chemical properties.
• What is the role of excipients in pharmaceuticals?

  Excipients help deliver drugs effectively.
• In what products can formulations be found?

  Formulations can be found in cleaning products.
• What information might be found on product packaging regarding formulations?

  It may include the ratio of components.
• Why is the formulation of a product vital in industries?

  It ensures safety and effectiveness in use.
• If a melting point of aspirin is measured as 128-132 °C, what does this indicate?

  The sample is not pure aspirin.
• What are the boiling points of pure aspirin?

  136 °C and 140 °C.
• What does a melting point lower than expected indicate?

  It suggests impurities in the sample.
• What is the formula to calculate the R_f value in chromatography?

  R_f = distance travelled by substance / distance travelled by solvent.
• What are the tests for common gases?

  1. Chlorine
  2. Oxygen
  3. Carbon Dioxide
  4. Hydrogen
• What happens when hydrogen gas is tested with a lit splint?

  It produces a "squeaky pop" sound.
• What indicates the presence of carbon dioxide in a gas test?

  Limewater turns cloudy when carbon dioxide is present.
• What is the first step in testing for gases?

  Collect the gas produced during a reaction.
• What is the significance of the R_f value in chromatography?

  It helps identify substances based on their movement.
• What are the key components of chromatography?

  • Two phases: stationary and mobile
  • Separation of substances based on movement
  • Calculation of R_f values for identification
• What is the first step in chromatography?

  Draw a line on filter paper
• What happens when the solvent moves up the paper in chromatography?

  The dye separates into different colors
• How do you calculate the Rf value in chromatography?

  Distance moved by substance divided by solvent
• What indicates a compound's solubility in chromatography?

  The higher the color lands, the more soluble
• What is a chromatogram?

  A pattern of spots from chromatography
• What is purity in chemistry?

  A single element or compound, not mixed
• How can you identify substances using melting or boiling points?

  Pure substances have specific melting and boiling points
• What does a wider temperature range indicate about a mixture?

  The mixture is more impure
• What is a formulation in chemistry?

  • A mixture designed as a useful product
  • Examples include medicines, cleaning products, paints, fuels, and food
• What is the squeaky pop test used for?

  To test for hydrogen gas
• What happens when you pass gas through limewater?

  It tests for carbon dioxide presence
• What is the role of hydrochloric acid in gas preparation?

  It reacts with magnesium to produce gas
• What is the purpose of adding sodium carbonate in gas preparation?

  To test the rate of reaction
• What is the chemical formula for oxygen gas?

  O₂
• What is the chemical formula for hydrogen gas?

  H₂
• What is the chemical formula for carbon dioxide?

  CO₂
• What is the purpose of a delivery tube in gas testing?

  To transport gas to the test area
• What is the role of a boiling tube in gas preparation?

  To contain the reaction mixture
• What does the term 'mobile phase' refer to in chromatography?

  The solvent that moves up the paper
• What does the term 'stationary phase' refer to in chromatography?

  The filter paper that does not move
• What is the purpose of placing a lid on the beaker during chromatography?

  To prevent evaporation of the solvent