What is boiling point
1 answer:
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Answer:
pH of the benzoic acid solution = 3.35
Explanation:
Benzoic acid is a weak monoprotic acid
pKa = 4.2
⇒ Ka = 6.3 x 10⁻⁵
C₆H₅COOH ⇄ C₆H₅COO⁻ + H⁺
Initial concentration C molar 0 0
At equilibrium (c - cα) cα cα
Acid dissociation constant Ka =
⇒ 6.3 x 10⁻⁵ = α²c ................(1)
(for weak electrolyte 1 -α = 1)
Concentration of benzoic acid C = 25 x 0.126 x 10⁻³ = 0.00315 molar
From eqn (1)
α² =
⇒ α = √( )
⇒ α = 0.14
So concentration of H⁺ ion = 0.14 x 0.00315 = 0.000441
pH = - log 0.000441 = 3.35
We not considered H⁺ concentration of water because pH < 7
Answer : The correct option is, 0.21 moles
Solution : Given,
Molarity of the solution = 0.85 M = 0.85 mole/L
Volume of solution = 250 ml = 0.25 L
Molarity : It is defined as the number of moles of solute present in one liter of the solution.
Formula used :
Now put all the given values in this formula, we get the moles of solute of the solution.
Therefore, the moles of solute is, 0.21 moles