Chem Tests Flashcards
yeet yeet
Flame Test
Identify metal ions
Lithium (Li+) - Crimson Potassium (K+) - Lilac Calcium (Ca2+) - orange-red Copper (Cu2+) - Green Sodium (Na+) - Yellow
Flame Test Practical
- Cleaning a nichrome wire loop by submerging it in dilute hydrochloric acid
- Dip wire loop into the sample to be tested
- Wire loop is held in the blue flame of a Bunsen and colour is recorded
Hydroxide precipitate tests
Identify metal ions using sodium hydroxide (NaOH)
Iron(II) ions (Fe2+) - Green
Iron(III) ions (Fe3+) - Orange-brown
Copper(II) ions (Cu2+) - blue
Calcium ions (Ca2+) - White precipitate of calcium hydroxide
Zinc ions (Zn2+) - White precipitate of zinc hydroxide
In excess NaOH zinc hydroxide dissolves to form a colourless solution
Calcium hydroxide does not
Carbonate ions
Compounds that contain CO3^2-) ions and react with dilute acids to form a salt, CO2 and H20
E.G: Calcium carbonate + NaOH -> Calcium chloride + CO2 + H20
- Add a few drops of dilute HCl
- If carbonate ions are present, bubbles of gas produced. It’s CO2.
You can confirm by using limewater
Carbon Dioxide
Bubble the gas through lime water
If CO2 present, limewater turns cloudy
Limewater = calcium hydroxide solution
Calcium hydroxide + CO2 -> H20 and a solid white precipitate of calcium carbonate
The calcium carbonate is what turns it cloudy
Halide ions (anions)
Negatively charged ions (anions)
- Add dilute nitric acid to remove any carbonate ions
- Silver nitrate then added. If halide ions are present, they will form a precipitate with the silver ins
Halide ions
Chlorine - Silver chloride - White
Bromine - Silver bromide - Cream
Iodine - Silver iodide - Yellow
Sulfate ions
Compounds that contain SO4^2- ions
- HCl added to remove carbonate ions
- Barium chloride is then added
If sulfates present, a white precipitate of barium sulfate will form
Chlorine
- Dampen blue litmus paper
- Hold paper near a container that holds substance
- If chlorine present, the paper turns red then white
Chlorine dissolves in water to form an acidic solution
Acidic, hence why it turns red
Chlorine also bleaches dyes
Hence why it turns white, it bleaches is
Hydrogen
Lighted splint in container of gas
If hydrogen is present, it should ignite with a squeaky pop
Oxygen
Glowing splint in container of gas
If O2 present, splint should relight