pls help me answer these questions for me. The normal boiling point of methanol
ID: 518341 • Letter: P
Question
pls help me answer these questions for me.
The normal boiling point of methanol is 64.7 degree C and the molar enthalpy of vaporization is 71.8 kJ/mol. Calculate the value of Delta S when 2.15 mol of CH_3 OH (l) vaporizes at 64.7 degree C. What is the coefficient of the dichromate ion when the following equation is balanced? Fe^2+ + Cr_2 O_7 2- rightarrow Fe^3+ + cr^3+ (acidic solution) Which transformation could take place at the anode of an electrochemical cell? A) CO_2 rightarrow Cr_2 O_4^2- B) VO_2^+ rightarrow VO^2+ C) H_2 AsO_4 rightarrow H_3 As O_3 D) O_2 rightarrow H_2 O_2 E) NO rightarrow NO_3^-Explanation / Answer
7)
Heat absorbed by methanol for vapourisation,
Q = n*Hvap
= 2.15 mol * 71.8 KJ/mol
= 154.37 KJ
This heat is supplied by surrounding
Qsurr = -154.37 KJ
T = 64.7 oC = (64.7 + 273) K = 337.7 K
use:
delta Ssurr = Qsurr/T
= -154.37 KJ / 337.7 K
= - 0.457 KJ/K
= - 457 J/K
Answer: - 457 J/K
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