According to your observations, should the solvation process be considered spontaneous or nonspontaneous?

Explanation:

Any system's spontaneity or non-spontaneity depends on the enthalpy change of the system and the entropy change.

If the value of enthalpy change is negative which means that the heat is being evolved, the system is spontaneous and the solute is likely to dissolve in the solvent.

On the other hand, if the value of enthalpy change is positive which means that the heat has to required for the solvation to occur, the system is spontaneous and the solute is likely to dissolve in the solvent. The spontaneity also depends on the entropy change and sometimes overweight the positive enthalpy change and makes the solvation spontaneous.

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