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TyrannosaureBeta9806

Hi! I am currently learning thermochemistry in my sec five chemistry class and I had a question.

In a exothermic process , the reaction release heat. When using the equation q= mc delta T , the delta T is (Tf-Ti)-> ( low temperature- high temperature) , this leads to the q to be negative.

So q (heat) of an exothermic process is -. But , why do we say that in a exothermic process , the temperature is increasing? Are we saying that the surrounding temperature is increasing?

I am having the same trouble with the endothermic process. Thank you!

CielFantastique1521

Hi TyrannosaureBeta9806,

Thank you for your question!

As stated previously by HobbitCharismatique7483, a negative q means that heat is released, whereas a positive q means heat is absorbed. When q is negative, the substance has released heat in its surrounding environment, which is why we say the temperature is increasing (in the environment or in another substance). So you guessed it right, good job!

The same principle applies to endothermic reactions: heat decreases in the surrounding environment and increases in the substance.

You can find more information here if needed:

https://www.alloprof.qc.ca/fr/eleves/bv/chimie/la-calorimetrie-q-m-c-deltat-c1025

I hope this answered your question! Don't hesitate to write to us again!

HobbitCharismatique7483

Hi, an exothermic reaction means that the system becomes colder by releasing heat (energy) into its surrounding environment. When q is negative, you have an exothermic reaction, because the amount of heat at the end (Tf) is inferior to the amount of heat at the beginning (Ti). For example, if you put water in a mold and then put it in the freezer, it’s an exothermic reaction: the liquid water will release its heat and become colder and colder, until it’s frozen!