Unit 3 & 4 Chemical tests

add bromine water. A positive test results in the solution turning from orange to colourless.

Add $PCl_5$ at room temperature. A positive test results in a rapid exothermic reaction, and the production of white misty fumes of HCl, which turn blue litmus red

Add acidified potassium dichromate. Primary and secondary alcohols will be oxidised, giving a carbonyl which may be tested further. The tertiary alcohol will not react

Add 2,4-dinitrophenylhydrazine (2,4-DNPH). A positive test will result in an orange crystalline precipitate. The dinitrophenyl hydrazone precipitate's melting point is indicative of the aldhyde or ketone from which it was formed.

A.) The addition of Fehlings solution and heat. An aldehyde will form a brick red precipitate ($Cu_2O$)
B.) The addition of Tollen's reagent and gentle heat. An aldehyde will cause a silver mirror or a black precipitate

Warm the unknown in a dilute solution of NaOH in alcohol. Acidify with dilute nitric acid then add silver nitrate solution. A positive test will result in a white, cream, and yellow precipitate for chlorides, bromides, and iodides respectively.

Add sodium hydrogencarbonate ($NaHCO_3$). A positive test will result in efferfescence. This can be confirmed by bubbling the produced gas through lime water, which should turn cloudy.

The iodoform test: Add a few drops of aqueous alkali iodine, then gently heat. A positive test will result in a primrose yellow precipitate of triodomethane

Add hydrochloric acid and test any gass produced by bubbling through lime water

Heat and test any gas produced with limewater

Add dilute nitric acid then barium chloride solution. A positive test will result in a dense white precipitate of barium sulfate

Add dilute hydrochloric acid. A positive test will result in pungent, toxic sulfur dioxide being produced. This will decolourise manganate (vii) solution

Test for sulfate (vi), and then test for acidity using universal indicator. Hydrogensulfate dissociates to form an acidic solution

Add dilute nitric acid followed by silver Nitrate solution. A white precipitate will form. This can be further confirmed by adding dilute ammonia. The precipitate should redisolve

Add dilute nitric acid followed by silver Nitrate solution. A cream precipitate will form. This can be further confirmed by adding concentrated ammonia. The precipitate should redisolve

Add dilute nitric acid followed by silver Nitrate solution. A pale yellow precipitate will form. This can be further confirmed by adding concentrated ammonia. The precipitate shouldn't redisolve

Flame test: Deep yellow flame

Flame test: Lilac flame

Flame test: Brick red flame

Flame test: Apple green flame

Flame test: Scarlett red flame

Blue litmus paper. A positive test turns the paper red then quickly bleaches it

1.) Add $FeCl_3$. A positive test will result in a violet solution
2.) Add bromine water. The solution will go from brown to colourless and a white precipitate will form

Heat gently with sodium hydroxide. A positive test will result in the release of ammonnia with its characteristic smell, and it will also turn red litmus blue.

React the amine with nitrous acid ($HNO_2$) formed in situ from $H_2SO_4$ and $NaNO_2$ under 10°. If fizzing is immediately observed, it's an aliphatic amine. If it only begins fizzing when heated above 10°, then it's an aromatic amine

Group 1 sulfates, hydroxides, and carbonates are all soluble. Group 2 sulphates decrease in solubility down the group, whilst group 2 hydroxides increase down the group. All group 2 carbonates are sparingly soluble

Add a few drops of aqueous potassium iodide, A positive test results in a canary yellow precipitate of lead ii iodide

$2Cu^{2+} + 4I^- \rightarrow 2CuI + I_2$