0.5000 g of oxalic acid (H2C2O4) is dissolved in about 250 ml of0.5M H2SO4. A so

Question

0.5000 g of oxalic acid (H2C2O4) is dissolved in about 250 ml of0.5M H2SO4. A solution of potassium permanganate (KMnO4) is darkpurple. When that solution is slowly added to oxalic acid thepurple color disappears, because the products given below areessentially colorless.

Unbalanced equation

H2C2O4 (aq) + MnO4- (aq) = CO2 (g) + Mn+2 (aq)

When adding just one drop beyond 43.47 ml of the permanganatesolution to the oxalate solution, the solution turns light purple.What is the concentration of the permanganate solution?

Balanced equation

Explanation / Answer

Mass of oxalic acid = 0.5000 g . Moles of oxalic acid = mass / molar mass                                =0.5 g / 90.3 g/mol                               = 0.0055 moles . 5H2C02O4 + 2MnO4 {-} + 6H {+} = 10CO2 + 2Mn {2+} + 8H2O
. From the equation, we can see that 5 moles of oxalic acidreact with 2 moles of MnO4 So moles of potassium permangnate = 0.0055 moles of oxalicacid * ( 2 moles MnO4 / 5 moles oxalic acid)                                                       = 0.0022 moles MnO4 solution . Volume of permangnate = 43.47 mL = 0.04347 L Molarity of permangnate solution = moles / volume                                                  = 0.0022 moles / 0.04347 L                                                   =0.05 M

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