11197130
Description
Flashcards by Kiranmayi Bapi, updated more than 1 year ago
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Created by Kiranmayi Bapi
over 6 years ago
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| Question | Answer |
| Group 1 Alkali Metals | Consists of Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb) Caesium (Cs) and Francium (Fr) (radioactive) General config- ns1 |
| Physical Properties | soft in nature and can be cut with knife except lithium Alkali metals have the largest atoms in their respective periods melting and boiling points are very low because of weak inter metallic bonds |
| Physical Properties (contd...) | first ionization enthalpy of the alkali metals are the lowest as compared to other elements show +1 oxidation state strong tendency to lose electrons and act as good reducing agents Less reduction potential |
| Physical Properties (contd...) | alkali metals form ionic (electrovalent) compounds alkali metals are good conductors of heat and electricity Alkali metals (except Li) exhibit photoelectric effect alkali metals and their salts impart a characteristic colour to flame |
| Flame Test | Li - Crimson Red Na - Golden Yellow K - Pale Violet Rb - Violet Cs - Sky Blue |
| Chemical Properties With Water | alkali metals, their oxides, peroxides and superoxides readily dissolve in water to produce corresponding hydroxides which are strong alkalies |
| Chemical Properties With Water (cont...) | 2Na + 2H2O → 2NaOH + H2 Na2O + 2H2O 2NaOH Na2O2 + 2H2O → 2NaOH + H2O2 2KO2 + 2H2O → 2KOH + H2O2 + O2 |
| Chemical Properties With Water (cont...) | strength of these hydroxides increases as we move down the group Li to Cs these hydroxides are highly soluble in water and thermally stable except lithium hydroxide Alkali metal hydroxides are strongly basic and react with all acids forming salts |
| Reaction with Acids | Alkali metal hydroxides are strongly basic and react with all acids forming salts & water NaOH + HCI → NacI + H2O 2NaOH + H2 SO4 → Na2SO4 + 2H2O |
| Reaction with Halogens | M2O + 2HX → 2MX + H2O MOH + HX → MX + H2O M2CO3 + 2HX → 2MX + CO2 + H2O (M is the metal = Li, Na, K, Rb or Cs) (X is the halogen = F, Cl, Br or I) |
| Ionization Enthalpy | Increases as we go from left to right in a period and from top to bottom in a group! |
| Lattice Energy | a measure of the energy contained in the crystal lattice of a compound, equal to the energy that would be released if the component ions were brought together from infinity- Noticed in alkali metal halides Lattice energy reduces across the group as the radius increases and it increases across the period as the atomic radius decreases |
| Hydration Energy | 1.Amount of energy released when one mole of gaseous ions combine with water to form hydrated ions 2. Li halides have the highest hydration energy and is soluble in water. 3. Solubility of alkali halides decreases down the group |
| Anomalous behavior of Li | 1. Li reacts with Oxygen to form oxide and the rest form peroxides or superoxides 2. Lithium Nitrates gives Lithium Oxide or decomposing. Remaining give respective nitrites 3. LiCI2H2O. & MgCI2.8H2O are deliquescent and crystallize as hydrate, Other alkali metals do not form hydrates. |
| Diagonal relationship between Li and Mg | 1. Both have same polarizing power 2. Both are hard 3. Both Hydroxides are basic in nature 3. due to their covalent nature, their halides are soluble in organic solvents 4. Reacts with Nitrogen to form Nitride 5. Both form hydrates |
| Diagonal relationship between Li and Mg | 6. Both readily react with Carbon and form Carbides 7. Carbonates, Hydrides and Nitrates of both Li & Mg decompose on heating 8. Hydrogen carbonates of both Li and Mg cannot be isolated in solid state |
| Sodium Hydroxide (NaOH) Properties | 1. Is stable when heated 2. When heated with Carbon, it is reduced and gives Hydrogen 2NaOH + 2C → 2Na +2CO + H2 |
| Uses | 1. It is used in the manufacture of paper, soap and artificial silk 2. in petroleum refining 3. for mercerizing cotton. 4. for the preparation of sodium metal and many salts of sodium. |
| Sodium Carbonate (Washing soda) (Na2CO3) | Prepared through Solvay process: Carbon dioxide gas is bubbled through a brine solution saturated with ammonia and itresults in the formation of sodium hydrogen carbonate |
| Sodium Carbonate (Washing soda) (Na2CO3) | NH3 + H2O + CO2 → NH4HCO3 NaCI + NH4HCO3 → NaHCO3 + NH4CI Sodium hydrogen carbonate so formed precipitates out because of the common ion effect caused due to the presence of excess of NaCl. The precipitated NaHCO3 is filtered off and then ignited to get Na2CO3. 2NaHCO3 → Na2CO3 + CO2 + H2O |
| Properties - NaHCO3 | The aqueous solution absorbs CO2 yielding sparingly soluble sodium bicarbonate. Na2CO3 + H2O + CO2 → 2NaHCO3 |
| Properties - NaHCO3 | dissolves in acids with an effervescence of carbondioxide and is causticised by lime to give caustic soda. Na2CO3 + 2HCl →2NaCl + H2O + CO2 Na2CO3 + Ca(OH)2 → 2NaOH + CaCO3 |
| Properties - NaHCO3 | Fusion with silica, sodium carbonate yields sodium silicate. Na2CO3 + SiO2 → Na2SiO3 + CO2 |
| Properties - NaHCO3 | Hydrolysis – being a salt of a strong base (NaOH) and weak acid (H2CO3), when dissolved in water sodium carbonate. Undergoes hydrolysis to form an alkaline solution Na2CO3 + 2H2O→ H2CO3 + 2NaOH |
| Uses - NaHCO3 | 1. used for softening hard water. 2. A mixture of sodium carbonate & potassium carbonate is used as fusion mixture. 3. As an important laboratory reagent both in qualitative and quantitative analyses. 4. used in paper, paints and textile industries. 5. for washing purposes in laundry. 6. in the manufacture of glass, borax, soap and caustic soda. |
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