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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Win,odd Dhamnekar on September 13, 2021, 11:11:00 AM

Title: Equivalent based questions (Valency Factors)
Post by: Win,odd Dhamnekar on September 13, 2021, 11:11:00 AM
Answers to d : 5 moles of Ferrous Oxalate (FeC2O4) are required to reduce 2 moles of Potassium Permanganate in acidic medium

Answer to e: Redox equation is $$K_2Cr_2O_7 + 3 Cu_2S + 14 H^+ \rightarrow 6 Cu^{2+} +3 S + 7 H_2O + 2K^+ + 2 Cr$$

From the aforesaid equation, we can say that $\frac56$ moles of  K2Cr2O7 is required to react completely with 2.5 moles of  Cu2S in acidic medium.
Title: Re: Equivalent based questions (Valency Factors)
Post by: Borek on September 13, 2021, 12:42:43 PM
When using dichromate for oxidation Cr is not reduced to solid metal.
Title: Re: Equivalent based questions (Valency Factors)
Post by: Win,odd Dhamnekar on September 13, 2021, 01:45:04 PM
My answer to a) is wrong. I have two probable  answers 1)75 ml of K2Cr2O7.

It is computed as under:
0.3 M = 300 mmol  :rarrow:50 ml of 300mmol = 15mmol
So  volume of Potassium Dichromate × 0.2 M = 15mmol :rarrow: volume of K2Cr2O7= 75 ml

2) Using this formula v.f.1 × M1 × volume1= v.f.2× M2 × volume2
Plugging in the values available with us into this formula, we have 6×0.2M× V1=2×0.3M × 50 ml

= 25 ml of Potassium Dichromate

Which of the above answer is correct?

Title: Re: Equivalent based questions (Valency Factors)
Post by: Borek on September 13, 2021, 04:19:11 PM