An unknown solid E has the following measured properties: • Melting point: 801 °C •…
CHEMISTRY · Multi-part · A Level · Chemistry · Amount of substance · Amount of substance
Problem
An unknown solid E has the following measured properties:
• Melting point: 801 °C
• Electrical conductivity: negligible in the solid state but high when melted
• Elemental composition by mass: 39.3 % Na and 60.7 % Cl
Atomic masses: Na = 22.99 g mol−1, Cl = 35.45 g mol−1
(1) Determine the empirical formula of substance E. Show all calculations.
(2) Classify substance E as molecular, ionic, or network covalent, and justify your classification using both its empirical formula and its electrical conductivity data.
(3) Explain why the observed difference in conductivity between the solid and molten forms of E is consistent with the bonding and structure you identified in part (b).