For each of the situations below, indicate whether the formulaweight calculated
ID: 76852 • Letter: F
Question
For each of the situations below, indicate whether the formulaweight calculated from the ideal gas law would be higher than,lower than, or the same as the true formula weight of the organiccompound. Give your reasoning in each case. (formula weight of thecompound is 67.0g/mol)a. The temperature of the boiling water is actually lower than thatrecorded.
b. The barometric pressure in the laboratory is actually higherthan that recorded.
c. Not all of the liquid has vaporized when the flask is removedfrom the boiling water bath.
Explanation / Answer
n, the number of moles, can also be written as, m / M, themass over the molecular mass So, P V M = m R Ta) Everything is constant except T and M: k M = T where k is an arbitrary constant (P V / m R) thatholds all terms that are held constant So if T is lower than expected, M is also lower than expected(they are directly related)
b) Everything is constant except P and M: P M = k where k is an arbitrary constant (m R T / V) thatholds all terms that are held constant So if P is higher than expected, M is lower thanexpected (they are indirectly related)
c) If most of the liquid boils off that means that there was justa contamination where it actually has a low boiling point but thereis some of "somethin else" that has a higher boiling point than thewater bath it is in. Therefore, this is unrelated to itsproperties and M is uneffected
Hope that helps b) Everything is constant except P and M: P M = k where k is an arbitrary constant (m R T / V) thatholds all terms that are held constant So if P is higher than expected, M is lower thanexpected (they are indirectly related)
c) If most of the liquid boils off that means that there was justa contamination where it actually has a low boiling point but thereis some of "somethin else" that has a higher boiling point than thewater bath it is in. Therefore, this is unrelated to itsproperties and M is uneffected
Hope that helps
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