Chemistry

Chemistry

Problem

Four separate solutions are prepared at 25\,∘^\circC. W. pH = 3.00 X. pH = 11.00 Y. [H3O+]=2.5×10−5 M[H_3O^+] = 2.5 \times 10^{-5}\,\text{M} Z. [OH−]=4.0×10−10 M[OH^-] = 4.0 \times 10^{-10}\,\text{M} Equal volumes of two of these solutions are mixed. Which pair will most closely produce a resultant mixture that is neutral? a) YY and ZZ b) XX and ZZ c) WW and XX d) XX and YY
Intuitive explanation

The key is recognizing that a neutral solution has [H3O+]=[OH−]=1×10−7 M[H_3O^+] = [OH^-] = 1 \times 10^{-7}\,\text{M} at 25°C. Convert all four solutions to either [H3O+][H_3O^+] or [OH−][OH^-], then identify which pair has equal molar amounts of acid and base—when mixed in equal volumes, they'll neutralize each other. The pair whose concentrations are closest to being reciprocals (one acidic, one basic) will produce the most neutral result.

Intuitive explanation

The key is recognizing that a neutral solution has [H3O+]=[OH−]=1×10−7 M[H_3O^+] = [OH^-] = 1 \times 10^{-7}\,\text{M} at 25°C. Convert all four solutions to either [H3O+][H_3O^+] or [OH−][OH^-], then identify which pair has equal molar amounts of acid and base—when mixed in equal volumes, they'll neutralize each other. The pair whose concentrations are closest to being reciprocals (one acidic, one basic) will produce the most neutral result.

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