2Cr^3 + 3Zn(s) -> 2Cr(s) + 3Zn^2 + (aq) which reactant is reduced and which is oxidicided

Cr is oxidised

and

Zn is reduced

[ Reduced reactant ] :

Cr^( + 3 ) + 3 e^( - 1 ) ===》 Cr^( 0 )

[ Oxidicided reactant ] :

Zn^(0) ===》Zn^( + 2 ) + 2 e^( - 1 )

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol