Pseudo-First-Order Rate Constant (k_obs = k [B]₀ (excess B))

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k_obs = k [B]₀ (excess B)

What each symbol means

SymbolWhat it stands for
kSecond-order constant (L mol⁻¹ s⁻¹)
k_obsObserved first-order constant (s⁻¹)
[B]₀Initial concentration of excess reactant (≈ constant)

When to use this

When [B] is in large excess, [B]≈[B]₀ and v = k_obs[A] with k_obs=k[B]₀.