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Old May 19th 2019, 06:16 AM   #1
JoeMan
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Does a neutralisation reaction with higher volumes create more heat?

In a multiple choice question, I assumed that half the volume of 2 acids and bases with constant concentrations would mean half the temperature. The answer suggests there is no change.

Can anyone explain this? I can't understand how presumably half the molecules can produce the same amount of heat.

The question:
- 50cm(^3) of 1M NaOH is neutralised by 50cm of 1M HNO3 to increase the temperature by 6C.
- The experiment is repeated with 25cm(^3) of each

I answered that the resultant temperature would increase by 3, but the answer is 6. Please help
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Old Aug 27th 2019, 12:35 AM   #2
chemtopper
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Heat liberated during neutralization reaction

In neutralization reaction the amount of heat released is due to combination of 1 mole of H+ with 1 mole of OH-to give one mole of water.
If the number of moles of H + and OH- are more due to more moles of acid and base then more heat is generated.
However if you have increased volume simply by dilution and not by adding more amount of acid or base then the amount of heat liberated will remain the same.
Remember Enthalpy change is always in terms of kilojoules per mole so volume has nothing doing with it.
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