[Community College] Thermodynamics

[igotrhythm]

I'm getting absolutely stonewalled by problems involving more than two components. Take this rather vanilla three-component problem:

A coffee cup calorimeter contains 480.0g of water at 25.00 C. To it are added: 380.0g of water at 53.5C and 525.0g water at 65.5C. Calculate the expected final temperature of the mixture.

Specific heat of water = 4.184 J/g*C

Gyah. I have no clue where to start, except maybe by treating it as two consecutive 2-component problems (add one sample, let it equalize, then add the other sample).

[dag12]

Re: [Community College] Thermodynamics

You can treat it as two separate problems. Just remember to use the summed mass of the first two components when you account for the final component.

[iironiic]

Re: [Community College] Thermodynamics

Pretty much what dag said. Also make sure that the units are consistent. In your proposed problem, everything works out accordingly, but there are many instances where they will give you the temperature in Kelvins or the mass in kilograms.

[igotrhythm]

Re: [Community College] Thermodynamics

I managed to work this specific problem by multiplying to get the total q of the system, then solving for T using the definition of specific heat. (q/mT = SH) This was only possible because it was all water. With more complex stuff like dropping hot metal into a calorimeter whose heat capacity must be taken into account, that kinda falls apart.

I'll keep trying. Thanks for the encouragement.