Deuterium (symbol D) is an isotope of hydrogen - VCE - SSCE Chemistry - Question 4 - 2005 - Paper 1

Given the equilibrium expression, we have:

$Kₑₑq = [D⁺][OD⁻]$

At neutral pH in D₂O, the concentrations of D⁺ and OD⁻ are equal. If we denote the concentration of D⁺ as $x$, then:

$Kₑₑq = x^2$

Substituting the given value of $Kₑₑq = 1.82 × 10^{-16}$,

$x^2 = 1.82 × 10^{-16}$

Taking the square root:

$x = ext{sqrt}(1.82 × 10^{-16})$

Calculating:

$x ≈ 1.35 × 10^{-8} ext{ M}$

Thus, the concentration of D⁺ is approximately $1.35 × 10^{-8}$ M.

Therefore, the correct answer is B. 1.35 × 10⁻⁸.