Tests

• Tests for gases

  • Hydrogen- lit splint burn with squeaky pop
  • Oxygen- glowing splint re-lit
  • Carbon dioxide- turns limewater cloudy
  • Ammonia- turns damp red litmus paper blue
  • Chlorine- turns damp blue litmus paper red b4 bleached white
• Hydrogen test


  Lit splint will burn with a squeaky pop
• Oxygen test


  Glowing splint will re-light
• Carbon dioxide test


  Turns limewater milky
• Ammonia test


  • Turns damp red litmus paper blue
  • Has a pungent odour
• Chlorine test


  Turns damp blue litmus paper red before bleaching it white
• Flame test


  1. Clean platinum or nichrome wire with concentrated hydrochloric acid

  2. Place acid-soaked wire into centre of hot Bunsen flame

  3. Place into sample of metal to be tested

  4. Place back into non-luminous flame
• Flame test results


  • Lithium, Li+ burns with a red flame
  • Sodium, Na+ burns with a yellow-orange flame
  • Potassium, K+ burns with a lilac flame
  • Calcium, Ca2+ burns with an orange-red flame
  • Copper, Cu2+ burns with a blue-green flame
• Test for positive ions (cations)


  Add alkali (e.g. sodium hydroxide NaOH) to solution
• Ammonium ion test


  • Reacting with sodium hydroxide results in formation of ammonia gas
  • Ammonia gas has pungent odour and turns damp red litmus paper blue
• Copper ion test


  Reacting with sodium hydroxide forms blue precipitate of copper (II) hydroxide, Cu(OH)2
• Iron (II) and Iron (III) ion tests


  Reacting with sodium hydroxide (NaOH) forms green iron (II) hydroxide, Fe(OH)2 and brown iron (III) hydroxide, Fe(OH)3 respectively
• Test for negative ions (anions)


  1. Add dilute nitric acid to remove carbonate or sulfate ions

  2. Add silver nitrate to form precipitates of silver chloride, silver bromide or silver iodide
• Carbonate ion test


  Reacting with acid (e.g. hydrochloric acid) forms carbon dioxide which can be tested by bubbling through limewater
• Sulfate ion test


  Add dilute hydrochloric acid then barium chloride to form insoluble white precipitate of barium sulfate
• Test for water

  1. Chemical test: Add anhydrous copper sulfate (white powder) which turns blue when hydrated

  2. Physical test: Heat to 100 degC and check if it boils completely
• Negative Ion Tests (Anions)

  A) AgCl

  B) AgBr

  C) AgI

  
• what do you add to each anion?

  fill in the blanks

  A) silver nitrate

  B) silver nitrate

  C) silver nitrate

  D) hydrochloric acid

  E) barium chloride

  
• Silver ions react with the halide ions to form precipitates of: Slv

  A) AgBr

  B) AgCl

  C) AgI

  D) Ag+

  
• What is the product of each anion test?

  fill in the blanks

  A) white precipitate

  B) AgCl

  C) cream precipitate

  D) AgBr

  E) yellow precipitate

  F) AgI

  G) CO2

  H) white precipitate

  I) BaSO4

  
• what reaction occurs between ammonia and litmus paper?

  fill in the blanks

  A) hydroxide ions

  B) ammonia

  C) red litmus paper

  D) damp

  E) hydroxide

  F) alkaline

  G) blue

  
• Flame tests (assign a metal to each flame color):

  A) lithium

  B) sodium

  C) potassium

  D) calcium

  E) copper

  
• Anion tests (assign an anion to each test):

  A) Cl-

  B) Br-

  C) I-

  D) COv3^2-

  E) SOv4^2-

  
• What does adding NaOH to each cation result in?

  fill in the blanks

  A) ammonia

  B) Cu(OH)2

  C) Fe(OH)2

  D) Fe(OH)3