Chemistry · Ionization of water, pH scale, common ion effect, hydrolysis of salts and pH of their solutions, the solubility of sparingly soluble salts, solubility products and buffer solutions

The pH of and at is:

The pH of \( D_{2} O \) and \( H_{2} O \) at \( 298 \mathrm{K} \) is:

  • A. 7.0, 7.0
  • B. 7.35, 7.0
  • C. 7.0,6.85
  • D. 6.85,7.35

Step-by-step solution

At 298 K, the pH of pure H2O is 7.0 due to its ion product Kw = 1.0×10⁻¹⁴. For D2O (heavy water), the ion product is lower (Kw ≈ 1.5×10⁻¹⁵), leading to pKw ≈ 14.82, so pH = pKw/2 ≈ 7.41. However, common reported value is 7.35, making option B correct.
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