17.1. Heat Flow http://www.ck12.org
FIGURE 17.4
This power plant in West Virginia, like
many others, is located next to a large
lake so that the water from the lake can
be used as a coolant. Cool water from
the lake is pumped into the plant, while
warmer water is pumped out of the plant
and back into the lake.change (∆T) is shown below.
q = m×cp×∆TThe heat that is either absorbed or released is measured in joules. The mass is measured in grams. The change in
temperature is given by∆T = Tf–Ti, where Tfis the final temperature and Tiis the initial temperature.
Sample Problem 17.1: Calculating Specific Heat
A 15.0 g piece of cadmium metal absorbs 134 J of heat as its temperature is increased from 24.0°C to 62.7°C.
Calculate the specific heat of cadmium.
Step 1: List the known quantities and plan the problem.
Known
- heat = q = 134 J
- mass = m = 15.0 g
- ∆T = 62.7°C –24.0°C = 38.7°C
Unknown
- cpof cadmium =? J/g•°C
The specific heat equation can be rearranged to solve for the specific heat.
Step 2: Solve.
cp=27.17 Q
m×∆T=
27.10 J
15 .0 g× 38. 7 ◦C= 0 .231 J/g·◦CStep 3: Think about your result.
The specific heat of cadmium, a metal, is fairly close to the specific heats of other metals in the table above (Table
17.1). The result has three significant figures.