Gas Tests

Gas Test Positive glowing splint reignites O2 H2 burning splint pops limewater cloudy CO2

Synthesis and Decomposition Reactions

Diatomic Elements: H2 (g) N2 (g) O2 (g) F2 (g) Cl2 (g) Br2 (l) I2(s) Polyatomic Elements: P4 (s) and S8 (s) Use Phase symbols (s) (l) (g) (aq)

Synthesis means to combine. Elements combine to form compounds. A + B  AB S8 (s) + O2 8 (g)  8 SO2 (g) 6 Li (s) + N2 (g)  2 Li3N (s) Ionic compounds are solid

Decomposition means to break down. Compounds break down into elements which requires energy that comes from heating or electrolysis. Electrolysis uses inert electrodes and an electric current through a molten or aqueous solution. AB  A + B heat ∆ 2 HgO (s)  2 Hg (l) + O2 (g) electrolysis 2 H2O (l)  2 H2 (g) + O2 (g)

Molten table salt is electrolyzed to produce molten sodium and another gas. ∆ 2 NaCl (l)  2 Na (l) + Cl2 (g) Nitrogen from the air reacts with oxygen to produce gaseous nitrogen dioxide. N2 (g) + 2 O2 (g)  2 NO2 (g)

A sample of Copper II oxide is heated. 2 CuO(s)  2 Cu (s) + O2 (g) A silver spoon tarnishes when exposed to sulfur. 16 Ag (s) + S8 (s)  8 Ag2S (s) Reaction Song