Sam records the mass of his evaporating dish as 6.251 g.

he records the mass of the evaporating dish and the sample of hydrate as 16.864 g.

after heating the sample in the evaporating dish to constant weight, the mass of them combined is 11.13 g.

how many moles of water were removed from the sample by the heating process?

report your answer with three digits after the decimal.

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

50.23 i believe is correct but don't quote me on that.