Expressing dilute sulfuric acid strength as normality: An aqueous solution contains 2.45% by weight H2SO4 and has specific gravity 1.011 (at the stated conditions). Calculate the acid strength expressed in normality (equivalents per litre).

Introduction / Context:
Normality (N) is commonly used for acid–base titrations and process dosing when the stoichiometric equivalents matter. For sulfuric acid (H2SO4), which is diprotic, the normality is twice the molarity if both protons are titratable. Here we convert a weight percent solution with known density (specific gravity) into normality directly on a per-litre basis.

Given Data / Assumptions:

• Mass fraction of H2SO4 = 2.45% w/w.
• Specific gravity (density) ≈ 1.011 g/mL ⇒ 1011 g per litre of solution.
• Equivalent weight of H2SO4 for acid–base reactions ≈ 98.08 / 2 ≈ 49 g/eq.
• Assume full 2-equivalent acidity of H2SO4 in this dilute range.

Concept / Approach:
Compute grams of H2SO4 present in one litre of solution from the given mass fraction and density, then divide by the equivalent weight to obtain equivalents per litre (normality). Alternatively, find molarity first and multiply by 2 for a diprotic acid; both routes should coincide for dilute solutions where full dissociation to 2 H+ is assumed in stoichiometric calculations.

Step-by-Step Solution:

Verification / Alternative check:
Independent routes (equivalent-weight method and molarity×2) agree within rounding, validating the computation and the assumption of full two-proton acidity for H2SO4 in such dilute solutions.

Why Other Options Are Wrong:

• 0.2500, 0.2528: these represent molarity, not normality, effectively missing the factor of 2 for diprotic acid.
• 0.5000: rounded too aggressively; slightly low compared with the precise density-based calculation.
• 0.3000: not supported by either molarity or equivalent-weight calculations.

Common Pitfalls:
Confusing molarity with normality; ignoring the density when converting weight percent to per-litre basis; using molecular weight instead of equivalent weight for polyprotic acids.

Final Answer:
0.5055