Question

In a `0.70 M` solution of benzoic acid, what percentage of the molecules are ionized (CHEMISTRY 1B problem)?

Benzoic acid is a weak acid that has antimicrobial properties. Its sodium salt, sodium benzoate, is a preservative found in foods, medications, and personal hygiene products. Benzoic acid dissociates in water:
`C_6H_5COOH⇌C_6H_5COO^−+H^+`
The `pKa` of this reaction is `4.2`. In a `0.70 M` solution of benzoic acid, what percentage of the molecules are ionized?
Express the percentage numerically using two significant figures.

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• Work
  
  It's incomplete, but I fulfilled the formula, and got (below)...
• Answer result
  

Answer 1

`pH=10.23`

( explanation under construction by question owner )

Explanation:

`8.5\times10^(-2)` M NaOCl

`K_a(HClO)=2.9\times10^(-8)`
`K_b(ClO^-)=(1.0\times10^(-14))/(2.9\times10^(-8))`