chemical analysis +earths atmosphere

• define purity


  purity is a substance containing only one type of element or compound
• what is indicative of purity

  the closeness of a substances boiling point to that of the official element or compound
• what is a formulation ?

  a substance with exact amounts of compounds engineered for a specific function
• what are the uses of formulations ?

  .used in medicine eg: to ensure drugs are deliverd to the correct part of the body

  .everyday life eg: paint, solvents, cleaning products, metal alloys like steel even food and drink
• what is the mobile phase of chromatography?

  where molecules can move, must be in liquid or gas
• what is the stationary phase of paper chromatography?

  where molecules cannot move - solid
• what is the purpose of chromatography

  to identify different substances through separation of mixtures
• what is Rf

  distance moved by substance/ distance moved by solvent
• what dictates how much a substance is absorbed up the paper?

  solubility vs absorbtion
• what are the tests for carbonate anions

  dilute acid - releases co2 - bubble through limewater
• what substance is limewater

  calcium hydroxide
• what is the test for sulphate ions

  add barium chloride - white precipitate
• how do you test for halide anions

  silver nitrate + nitric acid

  .chlorine - white

  .bromine - cream

  . iodine - yellow
• what are the results of the flame tests ?

  calcium - orange red

  copper - green

  Lithium - crimson

  pottasium - lilac

  sodium - yellow
• what is the test for cations (not flame)

  add sodium hydroxide solution
• what colour precipitates are formed from cations?

  calcium - white

  copper(II) - blue

  iron(II) - green

  iron (III) - brown

  aluminium- white- then redissolves in axcess NaOH into a colourless solution

  magnesium - white
• what are the types of air pollution + causes +where from

  .particulates - global dimming( bad for environment) and respitory problems. incomplete combustion

  .carbon monoxide can bind to haemaglobin replacing oxygen leading to coma and death. has no colour or smell. - incomplete combustion

  .sulfur dioxide comes from sulphur impurities in fuel and leads to acid rain

  .nitrous oxides occur when heat from car engins causes the nitrogen and oxygen in the air leading to acid rain
• what is flame emission spectroscopy

  an instrumental method used to identify metal ions in solutions. the sample is put into aflame and light given out is passed through a spectroscope. the line spectrum can be analysed to identify the metal ions in the solution and measure their concentrations
• What is the age of Earth according to current theories?

  4.6 billion years
• Why have theories about Earth's early atmosphere evolved?

  Due to limited evidence from 4.6 billion years ago
• What did intense volcanic activity release during Earth's first billion years?

  Gases forming an atmosphere similar to Mars and Venus
• What was the main gas in the early atmosphere?

  Carbon dioxide
• What other gases were released by volcanoes in the early atmosphere?

  Nitrogen, methane, and ammonia
• How did the formation of oceans affect atmospheric CO₂?

  Carbon dioxide dissolved in water, forming carbonates
• When did algae first produce oxygen through photosynthesis?

  Around 2.7 billion years ago
• What was the effect of increased oxygen levels over the next billion years?

  Allowed animals to evolve
• How did photosynthesis by algae and plants affect atmospheric CO₂?

  It reduced atmospheric CO₂ levels
• What processes removed carbon dioxide from the atmosphere?

  Formation of sedimentary rocks and fossil fuels
• What are the key stages in the evolution of Earth's atmosphere?

  • Intense volcanic activity released gases
  • Early atmosphere was mainly carbon dioxide
  • Formation of oceans led to carbonates
  • Algae produced oxygen around 2.7 billion years ago
  • Increased oxygen allowed animal evolution
  • Photosynthesis reduced atmospheric CO₂
  • Carbon dioxide removed through sedimentary rocks and fossil fuels