Answer:
5.90g of NaClO are needed
Explanation:
<em>Assuming the weak acid is HClO pKa = 7.54</em>
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To solve this question we must use the H-H equation for acids:
pH = pKa + log [A-] / [HA]
<em>Where pH is the pH we want = 7.74</em>
<em>pKa is pKa of the weak acid = 7.54</em>
<em>[A-] could be taken as the moles of the conjugate base (Moles NaClO) and [HA] moles weak acid = 0.500L * (0.10mol/L) = 0.0500 moles HClO</em>
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Replacing:
7.74 = 7.54 + log [NaClO] / [0.0500 moles]
0.20 = log [NaClO] / [0.0500 moles]
1.5849 = [NaClO] / [0.0500 moles]
Moles NaClO = 0.0792 moles
The mass is: -Molar mass NaClO = 74.44g/mol-
0.0792 moles * (74.44g / 1mol) =
<h3>5.90g of NaClO are needed</h3>