Write the net ionic equation for this reaction occurring in water: Potassium sulfate and
barium chloride are mixed to form potassium
chloride and barium sulfate.

1. No reaction occurs.
2. 2 K+ + 2 Cl− → 2 KCl
3. 2 K2SO4 + Ba2+ → 2 K+ + BaSO4
4. SO2−
4 + BaCl2 → 2 Cl− + BaSO4
5. SO2−
4 + Ba2+ → BaSO4

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