Notices
Results 1 to 6 of 6

Thread: Looking for a chemical with a specifc exothermic reaction.

  1. #1 Looking for a chemical with a specifc exothermic reaction. 
    Forum Freshman
    Join Date
    Oct 2014
    Location
    Belgium
    Posts
    11
    Does anybody know of any chemical which undergoes an exothermic reaction once it comes into contact with another chemical which produces say 50-100 degrees celcius of heat and can maintain this heat for several seconds? I would prefer it if neither of the chemicals involved were toxic to people, but if you know of chemicals that fit the above description but are toxic (or one of which is toxic) feel free to mention it anyway.


    Reply With Quote  
     

  2.  
     

  3. #2  
    Bullshit Intolerant PhDemon's Avatar
    Join Date
    Feb 2013
    Location
    Newcastle-upon-Tyne, UK
    Posts
    4,431
    Your question is too vague, without knowing the scale or what it is you are heating no one will be able to give you an answer.


    Reply With Quote  
     

  4. #3  
    Forum Freshman
    Join Date
    Oct 2014
    Location
    Belgium
    Posts
    11
    Quote Originally Posted by PhDemon View Post
    Your question is too vague, without knowing the scale or what it is you are heating no one will be able to give you an answer.
    I hope my reply to this comment is appropriate, considering that I am a layman. However, if by scale you mean physical scale, something the size of the head of a pin. It'd be heating lithium tantalate.

    Does that make the question clear enough?
    Reply With Quote  
     

  5. #4  
    Bullshit Intolerant PhDemon's Avatar
    Join Date
    Feb 2013
    Location
    Newcastle-upon-Tyne, UK
    Posts
    4,431
    Sort of, what you would then need to do is find the specific heat capacity of lithium tantalate, calculate how much energy would need to be released to heat whatever amount of this you have to the required temperature (once there it will take longer than a few seconds to cool so this should be enough). You then need to find a reaction that has an enthalpy change large enough to produce this amount of energy from such a small amount of material.
    Reply With Quote  
     

  6. #5  
    exchemist
    Join Date
    May 2013
    Location
    London
    Posts
    2,533
    Quote Originally Posted by OneOnOne1162 View Post
    Quote Originally Posted by PhDemon View Post
    Your question is too vague, without knowing the scale or what it is you are heating no one will be able to give you an answer.
    I hope my reply to this comment is appropriate, considering that I am a layman. However, if by scale you mean physical scale, something the size of the head of a pin. It'd be heating lithium tantalate.

    Does that make the question clear enough?
    THe heat given off by a reaction is characterised by the amount of ENERGY given out per mole of reactants. Its unit are kJ/mol. This is not a temperature, it is an amount of energy.

    What TEMPERATURE change this induces depends on what mass of material is in thermal contact with the reacting molecules and what its specific heat capacity is.
    Reply With Quote  
     

  7. #6  
    Forum Freshman
    Join Date
    Oct 2014
    Location
    Belgium
    Posts
    11
    Quote Originally Posted by PhDemon View Post
    Sort of, what you would then need to do is find the specific heat capacity of lithium tantalate, calculate how much energy would need to be released to heat whatever amount of this you have to the required temperature (once there it will take longer than a few seconds to cool so this should be enough). You then need to find a reaction that has an enthalpy change large enough to produce this amount of energy from such a small amount of material.
    From what I could find the specific heat capacity of lithium tantalate seems to be 676 J/(K*kg).
    The calculation I came up with was:
    676/(323,15*0,001) = X
    676/0,32315 = X
    2091,9077 J = X
    So does that mean to heat a single gram of lithium tantalate to 50 degrees celcius I need a reaction with as enthalpy of formation -2091,9077 joules or less or am I completely wrong here? Because it's been years since I've done anything like this and I had never even heard of enthalpy until today.
    Reply With Quote  
     

Similar Threads

  1. Change of mass in a chemical reaction
    By gonvaled in forum Chemistry
    Replies: 18
    Last Post: February 1st, 2013, 09:44 AM
  2. Reversal of Chemical Reaction
    By engineerjoe in forum Chemistry
    Replies: 6
    Last Post: April 18th, 2010, 07:10 AM
  3. Help: The Rate of Chemical Reaction
    By kwesifriends in forum Chemistry
    Replies: 5
    Last Post: March 13th, 2008, 10:06 AM
  4. Chemical reaction
    By dcowboys107 in forum Chemistry
    Replies: 5
    Last Post: January 21st, 2007, 07:30 PM
  5. Chemical reaction
    By jssb in forum Chemistry
    Replies: 2
    Last Post: May 19th, 2006, 04:52 AM
Tags for this Thread

View Tag Cloud

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •