# LAB 101: finding the final temperature of the system when they are in equilibrium?

1. Nov 20, 2012

### pmalayavech

1. The problem statement, all variables and given/known data

Need a second person to help verify if answer is correct.

Copper with a mass of 300 g initially at 200 °C is added to water with an initial temperature of 10 °C and mass of 500 g. What is the final temperature of the system when they are in equilibrium?

My variables

Cu specific heat: 385.112 J/kg C

Water specificheat: 4186 J

2. Relevant equations

Mm Cm (Tm - Tf) = Mw Cw (Tf-Tw)

3. The attempt at a solution

Mm Cm (Tm - Tf) = Mw Cw (Tf-Tw)

I convert g to kg for mass
500g to .500kg and 300g to .300kg

now plug equation and work the algebraic equation

(.300) (385.112)(200-tf) = (.500)(4186)(tf-10)

to

(23106.72-115.5336Tf)=(2093Tf-20930)

to

4036.72 = 2208.5336 Tf

to

19.93934799 = Tf

Tf= 19.9 J/kg C

Last edited: Nov 20, 2012
2. Nov 21, 2012

### Basic_Physics

Re: LAB 101: finding the final temperature of the system when they are in equilibrium

Get the same answer but units oC.

3. Nov 21, 2012

### pmalayavech

Re: LAB 101: finding the final temperature of the system when they are in equilibrium

so its not in Joules? but Celsius?

4. Nov 21, 2012

### haruspex

Re: LAB 101: finding the final temperature of the system when they are in equilibrium

Yes, the answer is a temperature, so it cannot be in Joules.
It is a good idea to include the units in the equations all the way through. This helps in two ways. It can show up dimensional mismatches (like Joules versus degrees) and also aids in conversion between different units of the same dimension (oC v. oF).