Problem: Oxalic acid, H2C2O4•2H2O (molar mass = 126.07 g/mol) is often used as a primary standard for the standardization of a NaOH solution. If 0.147 g of oxalic acid dihydrate is neutralized by 23.64mL of a NaOH solution, what is the molar concentration of the NaOH solution? Oxalic acid is a diprotic acid. (What is the balanced equation?)

FREE Expert Solution

Step 1. Write the chemical equation for the reaction

H2C2O4(aq) + 2 NaOH(aq) → 2 H2O(l) + C2O42-(aq)

*Main group metals should have a +3 charge or higher to be considered acidic. Na+ has only a +1 charge and is a neutral ion so it will not contribute to the pH of the solution


Step 2. Calculate the moles of H2C2O4

moles H2C2O4=0.147 g H2C2O4·2 H2O×1 mol H2C2O4·2 H2O126.07 g H2C2O4·2 H2O×1 mol H2C2O41 mol H2C2O4·2 H2O

moles H2C2O41.166×10‒3 mol


Step 3. Calculate the moles of NaOH using mole-to-mole comparison

moles NaOH=1.166×10-3 mol H2C2O4×2 mol NaOH1 mol H2C2O4

moles NaOH = 2.332×10‒3 mol


Step 4. Calculate the concentration of NaOH

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Problem Details

Oxalic acid, H2C2O4•2H2O (molar mass = 126.07 g/mol) is often used as a primary standard for the standardization of a NaOH solution. If 0.147 g of oxalic acid dihydrate is neutralized by 23.64mL of a NaOH solution, what is the molar concentration of the NaOH solution? Oxalic acid is a diprotic acid. (What is the balanced equation?)

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