Welcome Guest Search | Active Topics |

Tag as favorite
Impurities effect on melting point
Options
Previous Topic Next Topic
Lauren_6408
#1 Posted : Monday, June 21, 2021 7:08:11 AM
Rank: Member

Groups: Registered
Joined: 5/16/2021
Posts: 15

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
Hi,
I was wondering why impurities in a compound would only ever decrease the melting point and never increase it. I understand why the melting range is broadened and why the melting range would change but not the direction of the change. In my head I'm currently thinking that it's possible an impurity may have a higher melting point than the pure compound therefore increasing the melting point. If someone could explain this that would be awesome :)

Thanks
Back to top
Report?
INSTR_Katrina_128
#2 Posted : Tuesday, June 22, 2021 6:10:50 PM
Rank: Advanced Member

Groups: Registered
Joined: 5/18/2021
Posts: 73

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
Awesome question, Lauren!

Let's use water as an example. Water usually freezes/melts at 0°C. The molecules form a crystalline structure at this temperature composed of beautifully-arrangedd hexagonal rings (crystal lattice).

https://www.iceandclimat...IMGP0265_cut_500x220.jpg

Salt (an impurity that we like to add in the winter!) likes to GET IN THE WAY of this perfect crystal lattice structure and disrupt its formation. Instead, the water needs to force the salt crystals OUT, but this requires the water molecules to get even colder.

https://static.scientifi...190131-112389-ya1j16.jpg

I like to think that the salt is like a fake daredevil who's like "I can handle it, guys", but then when the water starts to get colder, it nopes right on out of there. 🙄

Adding an impurity will never increase the freezing/melting point, only DECREASE it.

Let me know if that helps. 😀
Back to top
Report?
Users browsing this topic
Guest (3)
Tag as favorite
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.

Clean Slate theme by Jaben Cargman (Tiny Gecko)
Powered by YAF | YAF © 2003-2009, Yet Another Forum.NET
This page was generated in 0.078 seconds.