Questions and Answers
What is the chemical formula for beryllium carbide?
What gas is produced when beryllium carbide reacts with water?
What is the brown gas produced when magnesium nitrate is heated?
What is the product formed when quick lime is heated in an electric furnace with powdered coke?
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What is the white precipitate formed when sodium chloride solution is added to zinc chloride solution?
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Why is Mg3N2 hydrolyzed?
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Why do alkaline earth metal salts contain more water of crystallization than corresponding alkali metal salts?
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What is the structure of BeCl2 in the vapour state?
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At what temperature does BeCl2 dissociate into a linear monomer?
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Which of the following is NOT a reason why HCl cannot be obtained from MgCl2 by reaction with water at room temperature?
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Study Notes
Alkali Metal Halides
- The correct order of lattice energy is: Fluoride > Chloride > Bromide > Iodide
- Lattice energy of the same metal reduces when the halogen's electronegativity lowers
- Lithium halides exhibit aberrant behavior due to their covalent character, whereas sodium and other halides are ionic in nature
- Melting points of halides decline as we travel down the group from sodium to cesium
- NaCl > KCl > RbCl > CsCl
Solubility of Halides of Alkali Metals
- Alkali metal halides have a range of solubilities
- Solubility of alkali metal fluorides in water gradually increases from lithium to caesium
- Lithium chloride has a far better solubility in water than sodium chloride when it comes to chlorides
- Solubility in water increases steadily from sodium chloride to cesium chloride as the lattice energy of the crystals decreases
Properties of Alkali Metal Halides
- In the fused condition, they are good conductors of electricity
- They are made up of ionic crystals
- Lithium halides have a partially covalent character due to the polarising power of lithium ions
- Lattice energy and polarising power are responsible for the structure and stability (solubility) of alkali metal halides
Lattice Energy
- Lattice energy is the energy produced during the production of a crystal lattice from gaseous cations and anions
- It is also the energy necessary to split one mole of a solid ionic compound into its gaseous ions
Properties of Sodium Oxide
- It combines with carbon dioxide to produce sodium carbonate and oxygen
- It is an oxidising agent and oxidises charcoal, CO, NH3, SO2
- It contains peroxide ion
Uses of Sodium Oxide
- For preparing H2O2, O2
- Oxygenating the air in submarines
- Oxidising agent in the laboratory
Properties of Potassium Oxides
- K2O is a white powder
- K2O2 is a white powder
- K2O3 is a red powder
- KO2 is a bright yellow powder
- KO3 is a reddish-brown needles
Properties of Magnesium Oxide
- It is a white powder
- Melting point of magnesium oxide is 2850 degree Celsius
- It imparts alkaline reaction and it is very slightly soluble in water
Properties of Calcium Oxide
- It is a white amorphous powder having a melting point of 2570 degree Celsius
- When heated in an oxygen-hydrogen flame, it produces strong light (lime light)
- It is a basic oxide that reacts with acidic oxides, such as sulphur dioxide
- On combination with water, it produces slaked lime
Hydroxides
Sodium Hydroxides
- Preparation: Electrolysis of Brine and Caustication of Na2CO3 (Gossage's method)
- Properties:
- Crystalline white solid that's highly corrosive and deliquescent
- Resistant to heat
- Aqueous solution has an alkaline pH and feels soapy to the touch
- FeCl3 + 3NaOH → Fe(OH)3 ↓ +3NaCl
- NH4Cl + NaOH → NaCl + NH3 ↑ +H2O
- ZnCl2 + 2NaOH → Zn(OH)2 ↓ +2NaCl
Potassium Hydroxide
- Preparation: Electrolysis of aqueous solution of potassium chloride
- Properties:
- Stronger base compared to sodium hydroxide
- More soluble in water as compared to sodium hydroxide
- Highly soluble in alcohol
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Description
Understand the properties of metal halides, including lattice energy, electronegativity, and melting points. Compare lithium halides to sodium and cesium halides in Class XI Chemistry.
