Question

suppose a 1.28 g sample of unknown x containing k 2 c 2 o 4 was dissolved in 25 ml of di water and 25 ml 3 m h 2 s o 4 and then titrated with 0.0655 m k m n o 4 . the sample required 27.60 ml of titrant to reach the endpoint. determine the mass percent k 2 c 2 o 4 in sample unknown x.

Answer 1

The percentage by mass of the oxalate is 58.4%.

A redox (reduction-oxidation) reaction is a chemical process in which electrons are transferred between two substances. It involves two half-reactions: oxidation and reduction.

We have the reaction equation as;

`2 KMnO_4 (aq) + 8 H_2SO_4 (aq) + 5 K_2C_2O_4 (aq) -- > 6 K_2SO_4 (aq) + 2 MnSO_4 (aq) + 8 H_2O (l) + 10 CO_2 (g)`

Number of moles of the permanganate = 27.60 /1000 L * 0.0655 m

= 0.0018 moles

If 2 moles of permanganate reacts with 5 moles of oxalate

0.0018 moles of permanganate reacts with 0.0018 * 5/2

= 0.0045 moles

Mass of the oxalate reacted = 0.0045 moles * 166 g/mol

= 0.747 g

Mass percent of the potassium oxalate = 0.747 g/1.28 g * 100/1

= 58.4%