A 318.0 g sample of hydrated calcium sulfate is warmed above a flame until all the water has evaporated the remaining calcium sulfate has a mass of 250,0 g. What is the chemical formula of the hydrated compound? (You may use a dash - in place of the dot)

just did the assignment and the answer was #1 +2 n

the dissolution of polymer can be thermodynamically described in 2 steps.

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

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