C8

• What is the field of chemical analysis also known as?

  Analytical chemistry
• What does chemical analysis involve?

  Separating, identifying, and quantifying substances
• What are some methods used in chemical analysis?

  • Paper chromatography
  • Filtration
  • Crystallization
  • Distillation
• What is a pure substance?

  Contains only one type of compound or element
• Why is saltwater not considered pure?

  It is a mixture of different compounds
• Why is the purity of a substance important?

  Only pure substances melt and boil at specific temperatures
• At what temperature does water boil?

  100 degrees Celsius
• At what temperature does sodium chloride melt?

  801 degrees Celsius
• What can boiling point tests help identify?

  Unknown substances based on boiling point
• What is a physical test in chemistry?

  Testing physical properties of a substance
• What is a chemical test in chemistry?

  Reacting a substance with another chemical
• How do impure substances behave in terms of melting and boiling points?

  They melt and boil over a range of temperatures
• What effect do impurities have on melting and boiling points?

  Lower melting point, increase boiling point
• What is the melting point of saltwater?

  About minus 2 degrees Celsius
• What is the boiling point of saltwater?

  Around 100.5 degrees Celsius
• What are formulations in chemistry?

  Mixtures prepared using a specific formula
• What is the purpose of formulations?

  To contain precise amounts of components
• How are formulations similar to recipes?

  They require specific proportions of components
• What might different components in a formulation contribute?

  Different properties for the final product
• What happens after testing different combinations in formulations?

  Find the right combination for repeated use
• What should you do if you enjoyed the video?

  Like and subscribe
• What technique is used to separate substances in a mixture?

  Chromatography
• What is the purpose of paper chromatography?

  To separate and identify substances in a mixture
• What is the first step in paper chromatography?

  Draw a baseline with a pencil
• Why is the solvent level kept shallow in paper chromatography?

  To avoid submerging the pencil line
• What happens to the different dyes during chromatography?

  They travel at different rates up the paper
• What is the pattern of spots left after chromatography called?

  Chromatogram
• What are the mobile and stationary phases in chromatography?

  Mobile phase is the solvent; stationary phase is the paper
• How do the properties of substances affect their movement in chromatography?

  Solubility determines how fast they move
• What does a single spot on a chromatogram indicate?

  The sample is a pure substance
• What is the formula for calculating the rf value?

  rf = distance travelled by substance / distance travelled by solvent
• If a pink substance travels 6 cm and the solvent travels 10 cm, what is the rf value?

  $0.6$
• How does changing the solvent or paper affect the chromatogram?

  It may change the rf values and pattern
• Why must chemists consider the solvent and paper type when looking up rf values?

  Different conditions affect the rf values
• What should you do to prevent solvent evaporation during chromatography?

  Place a lid on the beaker
• What happens if a chemical is not soluble in the solvent during chromatography?

  It remains on the baseline
• What is the significance of the chromatogram in identifying substances?

  It allows comparison with known data
• What are the four carbon gases tested in the video?

  Chlorine, oxygen, hydrogen, carbon dioxide
• What is the first step in testing for chlorine?

  Fill a test tube with the sample gas
• What happens to blue litmus paper when chlorine is present?

  It turns from blue to white