Question

Explain why result is higher than the actual value for the %Fe2+ with three reasons.

( The topic is Reduction-oxidation Titration)

The accepted value for the %Fe2+ is 9.10%. The experimental average of %Fe2+ is 9.65% which is higher than the accepted value. I need 3 reasons to explain why it is higher

Answer 1

Reasons for the higher percentage of iron are as follows :

1. The addition of stannous chloride should be made by a dropping bottle to avoid any large excess in the solution because its iresence will consume more K2Cr2O7 solution during titration and would thus register a higher percentage of iron.

2. The addition of HgCl2 is done in the cold reduces solution because in the hot condition the reaction between HgCl2 and SnCl2 may take place, precipitating mercury in a very finely divided state. This mercury will be oxidised by K2Cr2O7 and will thereby record a higher percentage of iron. 3. K2Cr2O7 solution when added must be stirred well thoroughly all the time otherwise it will give higher percentage of iron.