If you have the q cal of a reaction, then obviously you can convert to q chem by negating your q cal. But what if you need to get to q rxn (q of the reaction)? Also, my textbook is claiming that the q rxn = -(q sol + q cal). How does that figure into this?
I don't understand the question or your symbol meaning.
Question simplified: a) how do you get q of reaction if you have q of solution, b) how do you get q of reaction of you have q of calorimiter, c) how do you get q of solution if you have q of chemicals, d) in general, should q of chemicals equal q of solution, e) should q of calorimiter equal q of chemicals, f) should q of solution equal q of calorimiter?
I think you would do better to post a real, with numbers, instead of a general. In general, if one has q for the solution (I'm assuming something like a neutralization reaction), q reaction is q for the solution. Usually those problems ask for delta H/mol and you divide delta H by grams involved in the neutralization to obtain q/g or change to q/mol.
Usually q rxn + q calorimeter = heat input.
q for chemicals is
q = mass solvent x specific heat solvent x delta T.
I usually try to set them up so that
heat lost by one set + heat gained by another = 0.
To understand how to convert between q cal (heat transferred in calories) and q chem (heat transferred in chemistry units), we need to understand their relationship. The conversion factor between q cal and q chem can be obtained using the specific heat capacity of the substance involved in the reaction.
The equation q cal = m * C * ΔT relates the heat transferred (q cal) to the mass (m) of the substance, its specific heat capacity (C), and the change in temperature (ΔT). This equation allows us to calculate q cal when these variables are known.
To convert q cal to q chem, you need to use the conversion factor q chem = q cal / 4.18 J, where 4.18 J is the conversion factor between calories and joules.
Now let's move on to q rxn (heat of the reaction). Q rxn represents the heat transferred during a chemical reaction. It can be calculated using the following equation:
q rxn = -(q sol + q cal)
This equation states that the heat of the reaction (q rxn) is equal to the negative sum of the heat absorbed or released by the solution (q sol) and the heat transferred to the surroundings (q cal).
This equation makes sense because q sol represents the heat absorbed or released by the solution during the reaction, and q cal represents the heat transferred between the system and its surroundings. By summing their magnitudes and negating the total, we get the total heat of the reaction, q rxn.
In summary, to convert q cal to q chem, divide q cal by 4.18 J. To calculate q rxn, you can use the equation q rxn = -(q sol + q cal), where q sol is the heat absorbed or released by the solution, and q cal is the heat transferred between the system and its surroundings.