Chemistry Forums for Students > High School Chemistry Forum

Some Local ACS questions

(1/3) > >>

burntbacon:
I took the local ACS exam and have 2 questions that are iffy.

What is the first thing that happens to I2 (iodine) solid when it is slowly heated at 1 atm? a. melts b. vaporizes c. changes color d. becomes atoms

2 organic compounds are mixed with melting points 112 and 114.  What is the new melting point?
a. under 112 b. 112 c. between 112 and 114 d. over 114

thanks

Mitch:
2. The melting point is depressed, look up melting point depression.

burntbacon:
I figured as much, but from what point is the melting point depressed?  My teacher says it should be either below 112 or at 112.  But I think the melting point is depressed from 114, thus putting it between 112 and 114.  What's correct?  

hmx9123:
What was your answer for the first question, and why did you choose that answer?  I do have an opinion, but will wait until I hear from you.

burntbacon:
Well, for the iodine question, I answered that it "vaporizes" thinking it means sublime.  But after researching on the internet, I found a phase diagram showing that Iodine melts at 1 atm at about 113 C.  However, many places I look say that iodine sublimes at room temperature.  I guess the strict definition of vaporize is to go from liquid to gas...

I'm confused and I do not know what the answer is for 1.  

For 2, does Raoult's law only apply to solutions not pure liquids?  Just to make it easier, I put the melting points at 0 and -2 C.  The 0 has a higher melting point which will raise the melting point of the -2.  So the answer should be between 0 and -2.  Can I get a verification of the answer of 2, if the new melting point is between 112 and 114?

Navigation

[0] Message Index

[#] Next page