University:
Purdue University
Course:
CHM 11200 | General Chemistry
Academic year:

2024
Views:

482

Pages:

2
Author:

Laila Hale

Chemistry 11 – Taking a closer look at TYPES OF DECOMPOSITION REACTIONS ANSWERS 1) Metal carbonates decompose to produce metal oxides and carbon dioxide. Sodium carbonate → Na2CO3(s) → Na2O(s) + CO2(g) Calcium carbonate → calcium oxide + carbon dioxide CaCO3(s) → CaO(s) + CO2(g) Potassium carbonate → potassium oxide + carbon dioxide K2CO3 (s) → K2O (s) + CO2(g) 2) Metal hydroxides decompose to produce metal oxides and water. Calcium Hydroxide → Ca(OH)2 (s) → CaO (s) + H2O(l) Zinc hydroxide→ zinc oxide + water Zn(OH)2 (s) → ZnO (s) + H2O(l) Iron (III) hydroxide → iron (III) oxide + water 2Fe(OH)3 (s) → Fe2O3 (s) + 3H2O(l) 3) Metal chlorates decompose to produce metal chlorides and oxygen gas. Potassium chlorate → 2KClO3(s) → 2KCl(s) + 3O2(g) Magnesium chlorate → magnesium chloride + oxygen Mg(ClO3)2(s) → MgCl2 (s) + 3O2(g) Remember that diatomic elements like oxygen would be O2 even if they were liquid. A diatomic element is NOT dependent on it being in the gaseous state. Nickel (II) chlorate → nickel (II) chloride + oxygen Ni(ClO3)2(s) → NiCl2 (s) + 3O2(g) 4) Oxyacids decompose to produce water and a nonmetal oxide gas. Carbonic acid → H2CO3 (aq) → H2O (l) + CO2 (g) Sulphuric acid →water and Sulphur trioxide H2SO4 (aq) → H2O (l) + SO3 (g) Boric acid → water and diboron trioxide 2H3BO3 (aq) → 3H2O (l) + B2O3 (g) 5) Metal oxides decompose to produce metals and oxygen gas. Mercury (II) oxide → 2HgO (s) → 2Hg (l) +O2 (g) Mercury is a liquid at room temperature Copper (II) oxide → copper (solid at room temp) and oxygen (gas at room temp) 2CuO (s) → 2Cu (s) + O2 (g) Silver oxide → silver and oxygen Ag2O (s) → 2Ag (s) + ½ O2 (g) 7) Hydrates are compounds that readily absorb water into their crystal structure. When a hydrate decomposes, water is removed. Barium iodide dihyrate → BaI2 • 2H2O(s) →BaI2(s) + 2H2O(l) Copper (II) sulphate pentahydrate → copper (II) sulphate plus water CuSO4 • 5H2O(s) → CuSO4 (s) + 5H2O(l) Magnesium chloride hexahydrate → magnesium chloride plus water MgCl2 • 6H2O(s) →MgCl2(s) + 6H2O(l) 7) Some compounds can be decomposed by electricity into their elements. NOTE THAT This is very different than dissociation of solutions into ions! Sodium chloride → sodium solid and chlorine gas 2NaCl (s) →2Na(s) + Cl2(g) SOLID Silver bromide → (decomposition can occur with only the addition of sunlight) 2AgBr (s) →2Ag(s) + Br2(l) Bromine is a diatomic element. It is also a liquid at room temperature SOLID Aluminum oxide → 2Al2O3 (s) → 4Al (s) + 3O2 (g) 8) AS PART OF THE ABOVE CATEGORY, Water can decompose to produce oxygen gas and hydrogen gas. Often by the process of electrolysis (decomposition by applying electricity). WATER → hydrogen (gas) and oxygen (gas) 2H2O (l) → 2H2 (g) + O2 (g)