December 24, 2024, 08:45:11 AM
Forum Rules: Read This Before Posting


Topic: Mixed melting point - confirmation/criticism of my thoughts  (Read 4011 times)

0 Members and 1 Guest are viewing this topic.

Offline dev1

  • Very New Member
  • *
  • Posts: 1
  • Mole Snacks: +0/-1
Mixed melting point - confirmation/criticism of my thoughts
« on: September 21, 2009, 09:07:10 AM »
Hi, I was presented with the following question and I need confirmation/criticism on my answer:

If pure Acetylsalicylic acid is mixed in a 50:50 mixture with the following, what would you expect for the melting point?

a)Salicylic acid
b)Benzoin


Ok, so I know acetylsalicylic m.p. is 135-135.5 celsius, salicylic acid has a m.p. of 156-158 celsius, and benzoin has a m.p. of 132-133 celsius.

I'm not too sure on the question if it's asking for me to determine the actual eutectic point (e) with a range or just asking me what would happen but I presume it's the latter as it would be absurd for them to be asking me to calculate the e point without any background information.

Anyhow, I presume the answer is simply the melting point of the two constituents mixed in a 50:50 mixture will be less than the lower of the melting point of the two constituents alone. Is this correct?
i.e. salicylic acid and acetylsalicylic acid mixture of 50:50 will yield a melting point below that of acetylsalicylic acid (the lower of the two melting point ranges).
So, the m.p. range (eutectic point) is below 135-135.5.

Is that correct and is there a simple formula for calculating the eutectic point?

Offline KritikalMass

  • Full Member
  • ****
  • Posts: 139
  • Mole Snacks: +9/-6
Re: Mixed melting point - confirmation/criticism of my thoughts
« Reply #1 on: October 06, 2009, 12:09:35 AM »
My money is on them not wanting you to calculate the eutectic point.

Sponsored Links