The balanced net-ionic equation for the reaction between chromate and sulfite ion is given below. What volume (in L) of 0.333 M Na2CrO4 solution is required to react completely with 25.0 mL of 0.123 M Li2SO3? 2CrO42- (aq) + 10H+ (aq) + 3SO32- (aq) ---> 3SO42- (aq) + 2Cr3+ (aq) + 5H2O (l)

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

the answer is a! (2.9 x 10^-18 j) hope i could someone. : )