Https:\\gradycs. owschools. com * Practice Session - Atomic Structu x
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practice session/a4236?CFID=3ba3ce83-fe3f-40 62-9cbd-e13a357a3fc&CFTOKEN=0&a mp;sessionID=bd41de03d0&cratelD =24236&packID=ac1b0ec8qgCount=9 b1c6&qgList=bc12152c&
7
An atom is composed of a nucleus surrounded by electron clouds of varying sizes. The nucleus contains protons and neutrons,
while electrons move about the nucleus in the electron clouds

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