C07 Separation Techniques and Chemical Tests

C8.1 Know that chemical processes are required to displace constituent elements from their compounds

C8.2 Know that physical processes are required to separate mixtures, including miscible/immiscible liquids and dissolved/insoluble solids.

C8.3 Know when to apply the following separation techniques: simple/fractional distillation, paper chromatography (including use of R values), use of a separating funnel, centrifugation, dissolving, filtration, evaporation and crystallisation.

C8.4 Know how to establish the purity of a substance using chromatography.

C16.1 Know and recognise the following tests for gases:

a. hydrogen – explodes with a ‘squeaky pop’ when a burning splint is held at the open end of a test tube
b. oxygen – relights a glowing splint
c. carbon dioxide – limewater turns cloudy when shaken with the gas
d. chlorine – damp blue litmus paper turns red and then is bleached (paper turns white)

C16.2 Know, recognise and describe the following tests for the anions:

a. carbonates – using a dilute acid
b. halides – using an aqueous solution of silver nitrate in the presence of dilute nitric acid (chlorides form a white precipitate; bromides form a cream precipitate; iodides form a yellow precipitate)
c. sulfates – using an aqueous solution of barium chloride in the presence of dilute hydrochloric acid

C16.3 Know and recognise the test for the following metal cations using aqueous sodium hydroxide:

a. $\mathrm{A1}^{3+}, \mathrm{Ca}^{2+}$ and $\mathrm{Mg}^{2+}$ each form a white precipitate.
b. $\mathrm{Cu}^{2+}$ forms a blue precipitate.
c. $\mathrm{Fe}^{2+}$ forms a green precipitate.
d. $\mathrm{Fe}^{3+}$ forms a brown precipitate

C16.4 Recall and recognise the flame test for the cations of the following metals: $\mathrm{Li}$ (crimson red), $\mathrm{Na}$ (vellow-orange), $\mathrm{K}$ (lilac), $\mathrm{Ca}$ (red-orange), $\mathrm{Cu}$ (green)

C16.5 Know and recognise the test for the presence of water using anhydrous copper(II) sulfate (colour change from white to blue).