March 29, 2024, 07:51:16 AM
Forum Rules: Read This Before Posting


Topic: Melting Points  (Read 4432 times)

0 Members and 1 Guest are viewing this topic.

jena

  • Guest
Melting Points
« on: February 02, 2005, 05:22:10 PM »
Hi

I don't really understand the principle behind melting points? Why is necessary to know the melting points of an item?

Thank You  :)


Offline Mitch

  • General Chemist
  • Administrator
  • Sr. Member
  • *
  • Posts: 5298
  • Mole Snacks: +376/-3
  • Gender: Male
  • "I bring you peace." -Mr. Burns
    • Chemistry Blog
Re:Melting Points
« Reply #1 on: February 02, 2005, 05:45:23 PM »
They are used as a measure of purity.
Most Common Suggestions I Make on the Forums.
1. Start by writing a balanced chemical equation.
2. Don't confuse thermodynamic stability with chemical reactivity.
3. Forum Supports LaTex

Offline Donaldson Tan

  • Editor, New Asia Republic
  • Retired Staff
  • Sr. Member
  • *
  • Posts: 3177
  • Mole Snacks: +261/-13
  • Gender: Male
    • New Asia Republic
Re:Melting Points
« Reply #2 on: February 02, 2005, 07:10:03 PM »
if melting/freezing a substance is among the steps you take in a chemical process, you gotta know the melting point in order to make an estimate for the required energy input for the entire process. it's not only an economical issue but also knowing if your equipment can tolerate the heat output and pressure changes throughout the process.
"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006

dexangeles

  • Guest
Re:Melting Points
« Reply #3 on: February 03, 2005, 12:26:35 AM »
example1: you need to record the melting point of a salt substance and you decide to use a melt-temp....if you don't know the melting point is probably over 400 degrees, and you decide to use the melt-temp at #2 (slow heat) setting, you'll be there all day  ;)

example2: helps isolate a desired substance (just like distillation - gota know the Bp and keep it there to isolate the desired compound)

example3: it helps provide for finding out what an unkown is (besides ftir, nmr, gc, etc...)  Imagine if we don't have a CRC book for reference of melting points.  Organic is hard enough :'(

Sponsored Links