Chapter 16 Notes IIChapter 16 Notes IICalorimetryCalorimetry

What is calorimetry?

•Essentially, the science of measuring heat change.

•Using the specific heat of something you know to find the specific heat of something you don’t.

• It takes advantage of the law of conservation of energy.

What is calorimetry?

•The principal shows that heat lost by one substance has to equal heat gained by another.

When a hot object is put into cool water what happens?

Object at 100oC

Water at 20oC

Final temperature

of both is 22oC

50g

250g

50g

Heat lost is equal to heat gained, but temperature lost does NOT equal temperature gained

NOTICE:

So, to find the specific heat of the object…

•Solve q=mCT for heat gained by water

THEN•Use q you found to solve q=mCT for the specific heat of the object.

Calorimeters

•A calorimeter is a device that measures heat change.

• It can be extremely sophisticated, or as simple as two foam cups, a thermometer and water!

Ghetto KPHS Style Calorimeter

Bomb Calorimeter

Practice Problem #1

•What is the specific heat of a metal if a 50.8g sample at 100.0oC raises the temperature of 258.2g of water from 25.2oC to 28.1oC?

•What is the specific heat of a substance if a 22.6g sample at 104.5oC raises the temperature of 125.3g of water from 22.6oC to 33.1oC?

Practice Problem #2