In an experiment, 16.8 g of k2so4 was dissolved in 1.00 kg of water to make a solution. the freezing point of the solution was measured to be −0.405°c . calculate the van't hoff factor (i) for this solution. the freezing point of pure water is 0°c (exactly) at 1 atm pressure and the molal freezing-point depression constant for water is 1.86°c/m.

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