The correct option is D 116
Chemical reaction involved:
11 K2Cr2O7+6 Cu3P+62 H2SO4→
11 Cr2(SO4)3+18 CuSO4+6 H3PO4+
11 K2SO4+53 H2O
Given moles of Cu3P=1
Salts react in such a way that two or more atoms in the salt undergo a change in oxidation state as a result of either oxidation or reduction. In such a case, we can calculate the n - factor of the salt as the total increase or decrease in oxidation state per mole of the salt.
The oxidation state of Cu changes from +1 to +2 and the oxidation state of P changes from -3 to +5 (both Cu and P are oxidised). n-factor of Cu3P=3|2−1|+1|5−(−3)|
=11
For the given reaction,
Gram equivalents of K2Cr2O7= Gram equivalent of Cu3P
Number of moles × n-factor = Number of moles × n-factor.
n×6=1×11
n=116
Thus ,116 moles of K2Cr2O7 are required.
So, option (A) is the correct answer.
Additional Information:
Reaction Involved:
Cr2O−27+Cu3P→Cr3++PO2−4+Cu2+
O.S Cr=+6 Cu=+1 Cr=+3 P=+5 Cu=+2
O=−2 P=−3 O=−2
n-factor based on Cr2O2−7=(ΔO.S)×atoms of Cr in Cr2O2−7=(6−3)×2=6
n-factor based on Cu=(ΔO.S)×atoms of Cu in Cu3P=(2−1)×3=3
n-factor based on P=(ΔO.S)×atoms of P in Cu3P=[5−(−3)×1]=8
Thus, n-factor of Cu3P=11