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fredd [130]
3 years ago
12

citric acid has an acid dissociation constant of 8.4 x 10^-4 it would be most effective for preparation of a buffer with a pH of

(A) 2 (B) 3 (C) 4 (D) 5
Chemistry
1 answer:
Sloan [31]3 years ago
5 0

Answer:

(B) 3

Explanation:

Citric acid has an acid dissociation constant (Ka) of 8.4 × 10⁻⁴. When it forms a buffer with its conjugate base (citrate), we can calculate the pH using the Henderson-Hasselbalch's equation.

pH=pKa+log\frac{[base]}{[acid]}

The optimum range of pH is pKa ± 1. The pKa is -log Ka = -log (8.4 × 10⁻⁴) = 3.1. The buffer would be more effective for pH between 2.1 and 4.1, especially around 3.1. So the best choice is (B) 3.

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At a particular temperature, 12.0 moles of so3 is placed into a 3.0-l rigid container, and the so3 dissociates by the reaction 2
saul85 [17]
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I             12             0          0
C           -2x           +2x      +x
---------------------------------------------
E         12-2x          2x         x

Since the moles of SO₂ at equilibrium is 3 mol, 2x = 3. Then, x = 1.5 mol. So, the amounts at equilibrium is:
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<em>K = 0.0556</em>
4 0
3 years ago
A solution of salt and water is 33.0% salt by mass and has a density of 1.50 g/ml. what mass of the salt in grams is in 5.00l of
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To answer this item, we solve first for the mass of the solution by multiplying the density by the volume. That is,

      m = (density)(volume)

Substituting the known values,
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