CHEMISTRY · Multi-part · AP · Chemistry · Atomic Structure and Properties · Atomic Structure and Properties
Problem
Two colorless, water-soluble solids—G and H—have nearly identical molar masses (approximately 120 g mol−1). Preliminary qualitative tests reveal the following observations:
• When a small quantity of G is added to distilled water, the resulting solution has a measured electrical conductivity of 9.5 mS cm−1.
• An equimolar solution of H in distilled water has an electrical conductivity of 0.18 mS cm−1.
• Elemental analysis gives the following percent compositions by mass:
– G: 25.0 % Na, 19.0 % S, 56.0 % O
– H: 40.0 % C, 6.7 % H, 53.3 % O
Atomic masses: Na = 22.99 g mol−1, S = 32.1 g mol−1, O = 16.0 g mol−1, C = 12.0 g mol−1, H = 1.01 g mol−1
(1) For solid G, determine its empirical formula from the elemental analysis. Explain each step of your calculation.
(2) For solid H, determine its empirical formula from the elemental analysis. Explain each step of your calculation.
(3) Use both the empirical formulas and the conductivity data to classify each solid as molecular, ionic, or network covalent. Provide a clear, comparative justification for each classification.
(4) Design a brief laboratory procedure (maximum three steps) that would further confirm the type of bonding present in solid G without relying on electrical conductivity measurements. Include the observations that would support your conclusion.