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tatyana61 [14]
4 years ago
8

Calculate the pH of a buffer that is 0.020 M HF and 0.040 M NaF. The Ka for HF is 3.5 × 10-4.

Chemistry
2 answers:
LekaFEV [45]4 years ago
7 0

The given buffer solution is 0.020 M HF and 0.040 M NaF.

Given the K_{a} of HF is 3.5 * 10^{-4}

Finding out pK_{a}:

pK_{a} = -logK_{a}

= - log(3.5 * 10^{-4})

= 3.46

We use the Hendersen-Hasselbalch equation to find out the pH of a buffer solution:

pH = pK_{a} + log\frac{[Base]}{[Acid]}

[Base] =[NaF] = 0.040 M

[Acid] = [HF] =0.020 M

Plugging in the values to find out pH,

pH = 3.46 + log\frac{0.040}{0.020}

pH = 3.46 + log(2)

= 3.76

Therefore, pH of the buffer is 3.76

zzz [600]4 years ago
4 0
 <span>pH = pKa + log ([base]/[acid]) = -log (3.5 x 10^-4) + log (0.040/.020) = 3.46 - 0.30 = 3.16</span>
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x=(8.33*10⁻³ moles * 6.022*10²³ molecules)/1 mol≈5.0183*10²¹ molecules.

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4 years ago
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