Hydrogen chloride (HCl) has a melting point of -114.2 °C. Sodium chloride (NaCl) has a melting point of 801 °C. Explain in terms of structure and bonding why these substances have such different melting points?
Hydrogen chloride has a simple molecular structure. The atoms within the molecule are held together by strong covalent bonds. However, for simple covalent molecules to melt only the weak intermolecular forces need to be overcome (not the strong covalent bonds). This requires very little energy and thus the melting point is low.
Sodium chloride is a giant ionic lattice. To melt the substance the strong electrostatic attractions between oppositely charged ions (ionic bonds) must be overcome. This requires large amounts of energy and thus the melting point is high.
AJ
Related Chemistry GCSE answers
All answers ▸What is the volume of carbon dioxide released at room temperature and pressure when 6.2 g of copper carbonate reacts with excess dilute sulfuric acid?
name the type of bonding in a molecule of water.
Use your own knowledge to compare and contrast the physical and chemical properties of Transition metals and group 2 elements. Use examples to explain your answer.
Draw a labelled diagram of carbon.