Q.
How many grams of potassium dichromate me required to oxidise 20.0g of Fe2+ in FeSO4 to Fe3+ , if the reaction is carried out in an acidic medium? Molar masses of K2Cr2O7 and FeSO4 are 294 and 152 respectively.
K2Cr2O7+7H2SO4+6FeSO4→ 3Fe2(SO4)3+Cr2(SO4)3+7H2O+K2SO4 =294.6×154=912 ∵912g of FeSO4 oxidises by =294g of K2Cr2O7 ∴20g of FeSO4 oxidise by =6×154294×20gK2Cr2O7 =6.45g of K2Cr2O7