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Potassium hydrogen phthalate (KHP) is often used as a primary standard in acid–base titrations. If 19.45mL NaOH is required to neutralize 0.412g KHP what is the concentration of the NaOH?

User Grubsnik
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Final answer:

To find the concentration of the NaOH solution used to neutralize 0.412g of KHP, convert the mass of KHP to moles, use the stoichiometry to find moles of NaOH, and divide by the volume of NaOH solution in liters. The concentration of NaOH is calculated to be 0.1037 M.

Step-by-step explanation:

Calculating the Concentration of NaOH Solution

To calculate the concentration of the NaOH solution from the neutralization of KHP, we need to use the stoichiometric relationship between KHP and NaOH. The molar mass of KHP (C₈H₅KO₄) is approximately 204.22 g/mol, and it reacts with NaOH in a 1:1 molar ratio, as shown in the equation:

KHP(aq) + NaOH(aq) → KNaP(aq) + H₂O(l)

Using the given weight of KHP (0.412g), we can convert this to moles:

moles KHP = (0.412 g) / (204.22 g/mol) = 0.002017 mol

Since KHP reacts with NaOH in a 1:1 ratio, 0.002017 mol of NaOH is also needed to reach the neutralization point. Knowing the volume of the NaOH solution used, we can calculate its concentration:

Concentration NaOH = moles NaOH / volume NaOH(L)

Concentration NaOH = 0.002017 mol / 0.01945 L = 0.1037 M

The concentration of the NaOH solution is therefore 0.1037 M.

User MyOwnWay
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