1. Chemical Analysis L.O: L.O: To know how to analyse and identify metal ions in unknown substances Starter: Think of a few examples of why chemical identification may be needed by: Environment scientists Forensic Scientists Health Care Scientists

2. Forensic scientists have to identify lots of mystery substances. (explosives, drugs, soil in shoes) The problem is many substances look very similar! Forensic scientists have to identify lots of mystery substances. (explosives, drugs, soil in shoes) The problem is many substances look very similar! What could this be?

3. Environmental scientists might have to identify pollutants Environmental scientists might have to identify pollutants Healthcare scientists might have to identify drugs in athletes, substances in dialysis Healthcare scientists might have to identify drugs in athletes, substances in dialysis

4. Spot the mistakes Lithium ion Li + Lithium ion Li + Copper II ion Cu + Copper II ion Cu + Magnesium ion MG 2+ Magnesium ion MG 2+ Potassium ion P + Potassium ion P + Oxygen ion O 2- Oxygen ion O 2- Chlorine ion Cl - Chlorine ion Cl - Helium ion He + Helium ion He + Nitrogen ion N 3+ Nitrogen ion N 3+ Iron II ion Fe 2+ Iron II ion Fe 2+

5. Methods of Analysis Chemists are often asked to identify the ions present in a compound. Remember the instrumental methods in C2? Paper chromatography, Gas Chromatography, Mass Spectrometry? Disadvantages of Using Instrumental Methods Usually Expensive Need Special Training Results usually need to be compared to already known specimens Advantages of Instrumental methods Highly accurate Much Quicker Enable small quantities of chemicals to be analysed We are going to perform some human tests today. What are the advantages of doing these over instrumental tests?

6. Identifying Metal Ions Add sodium hydroxide to the solution Dirty Green Precipitate = Iron II Brown / Orange Precipitate = Iron III Light Blue Precipitate = Copper II White precipitate = Could be Calcium, Magnesium, Aluminium Add Excess Sodium Hydroxide White precipitate Disappears White precipitate doesn’t Disappear Aluminium Calcium or Magnesium Flame Tests Lithium = Crimson Sodium = Orange Potassium = Lilac Calcium = Brick Red Barium = Light green

7. Identifying Metal Ions Add sodium hydroxide to the solution Dirty Green Precipitate = Brown / Orange Precipitate = Light Blue Precipitate = White precipitate = Could be Calcium, Magnesium, Aluminium Add Excess Sodium Hydroxide White precipitate Disappears White precipitate doesn’t Disappear Flame Tests Lithium = Sodium = Potassium = Calcium = Barium =

8. PotassiumBariumSodiumCalciumLithium