What mass of sodium nitrite must be added to 350.mL of water to give a solution with pH = 8.40? [K_a(HNO₂)= 5.6 × 10^-4] A)68 g B)1.7 × 10^-4 g C)0.039 g D)8.3 g E)24 g

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Quizplus · Accepted Answer

To find the mass of sodium nitrite needed, we first calculate the concentration of OH⁻ ions using the pH. pH = 8.40 implies pOH = 14 - 8.40 = 5.60, so [OH⁻] = 10^(-5.60). Using the Kb of nitrite (Kb = Kw/Ka), we find the concentration of nitrite ions needed. Finally, we convert this concentration to mass using the molar mass of sodium nitrite. The calculations show that approximately 8.3 g of sodium nitrite is needed.

What Mass of Sodium Nitrite Must Be Added to 350