One kilogram of a polyester with a number-average molar mass M n = 10,000 g mol−1 is mixed with one kilogram of another polyester with a Mn = 30,000 g mol−1. The mixture then is heated to a temperature at which ester interchange occurs and the heating continued until full equilibration is achieved.
1. Assuming that the two original polyester samples and the new polyester, produced by the ester interchange reaction, have the most probable distribution of molar mass, calculate Mn and weight-average molar mass Mw for the mixture before and after the ester interchange reaction.

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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

on passing the small ampere of electric current through the tube made of ar and hg of cfl generates uv rays which excites the fluorescent and thus emits the high radiation by consumption of just 5- 12 w in comparison to incandescent light which requires more power such as around 40 - 55 w to lighten.

moreover the life span of fluorescent or cfl is around 8000 h whereas the life span of incandescent is around 1200 h

hence, the building installed with incandescent lights bears more electricity bill.