Basic Chemistry – Select the Atomic (Relative Atomic) Mass of Sulphur Choose the standard atomic mass of sulphur used in stoichiometric calculations and periodic-table data.

Introduction / Context:
Atomic (relative atomic) mass values are the foundation for stoichiometry, balancing chemical equations, and converting between moles and grams. The element sulphur, symbol S, commonly appears in combustion, environmental, and process-engineering problems. Knowing its standard atomic mass avoids calculation errors in mass and mole balances.

Given Data / Assumptions:

• Atomic masses are expressed relative to carbon-12 = 12 exactly.
• Periodic-table values are averaged over natural isotopic abundances.
• Engineering calculations often round to convenient integers when suitable.

Concept / Approach:

The commonly used atomic mass for sulphur in introductory and engineering problems is approximately 32 (more precisely about 32.06). For stoichiometry involving compounds such as SO2, SO3, H2S, or sulphates, rounding to 32 is standard practice and provides sufficient accuracy for most educational exercises and preliminary design work.

Step-by-Step Solution:

Verification / Alternative check:

Look at common compounds: sulphuric acid H2SO4 has molar mass ≈ 21 + 32 + 4*16 = 98 g/mol, which aligns with the accepted atomic mass of sulphur near 32.

Why Other Options Are Wrong:

12 is carbon, 14 is nitrogen, 16 is oxygen (atomic mass, not S), and 28 is silicon (approximate). Choosing any of these would cause large mole-balance errors.

Common Pitfalls:

Confusing atomic number (16 for S) with atomic mass (~32). Also, mixing isotope mass numbers (e.g., 32, 34) with the average atomic mass used for bulk natural sulphur.

Final Answer:

32