7212719
Description
Flashcards by Nancy Mathew, updated more than 1 year ago
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Created by Nancy Mathew
about 8 years ago
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| Question | Answer |
| Preparation of O2 in the laboratory | i. Heating oxygen containing salts (chlorates, nitrates, permanganates) ii. Thermal decomposition of metals iii. Decomposition of H2O2 into water and dioxygen |
| Heating of chlorate (reaction) | 2KClO3 -> KCl + 3O2 |
| Thermal decomposition of metals low in the electrochemical series or higher oxides of some metals (reaction) | 2Ag2O -> 4Ag +O2 2HgO -> 2Hg + O2 |
| Decomposition of hydrogen peroxide (reaction) | 2H2O2 -> 2H2O + o2 |
| Large scale preparation of dioxygen | (from water or air) ELECTROLYSIS OF WATER: Cathode: Hydrogen Anode: Oxygen |
| Industrial preparation of dioxygen | (from air) 1. Removal CO2 and water vapour 2. Liquefaction 3. Fractional distillation - gives dinitrogen and dioxygen |
| How do marine and aquatic life get oxygen? | Dioxygen is a colourless, odourless gas that has a SOLUBILITY of 3.08cm3 in 100cm3 of water. |
| Temperature at which O2 liquefies and freezes | 90K - liquefies 55K - freezes |
| Isotopes of O | O16, O17, O18 |
| Why is molecular oxygen unique? | It is paramagnetic despite having even number of electrons |
| Reactivity of dioxygen | Directly reacts with nearly all metals and non-metals (except Au, Pt and some noble gases) |
| How does it sustain reactions with other elements? | Its combination with other elements is often strongly exothermic. |
| Why is external heating required for initiating an oxidation reaction? | Bond dissociation enthalpy of oxygen=oxygen double-bond is HIGH (493.4 kJ/mol) |
| Reaction with metals | 2Ca + O2 -> 2CaO 4Al + 3O2 -> 2Al2O3 |
| Reaction with non-metals | P4 + 5O2 -> P4O10 C + O2 -> CO2 |
| Reaction with compounds | 2ZnS + 3O2 -> 2ZnO + 2SO2 (roasting of suphide ore) CH4 +2O2 -> CO2 + 2H2O (Combustion of fuel - methane) |
| Catalytic oxidation reactions | V2O5 2SO2 + O2 ------> 2SO3 Cu2Cl2 4HCl + O2 ------> 2Cl2 + 2H2O |
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