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# Specific Heat Capacity

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by

## Ms. Yucel

on 13 February 2014

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#### Transcript of Specific Heat Capacity

Specific Heat Capacity
Heat Capacity
The amount of heat energy required to raise the temperature of a certain material by 1˚C
How much energy must be transferred as heat to 420 kg of water in a bathtub in order to raise the water's temperature from 25℃ to 37℃?
What mass of water is required to absorb 4.7 x 10 J of energy from a car engine while the temperature increases from 298 K to 355 K?
A steel bolt gives up 1124 J of energy as its temperature drops 25 K. If the bolt's mass is 0.093 kg, what is its specific heat capacity?
Review!
Warm-up (Tuesday, Feb. 11)
You have
a 50g piece of aluminum (at room temperature)
a beaker half-full of water (at room temperature) that you also measure as 50g

You put both of these objects on the same hot plate. 5 minutes later, which object will feel hotter to your hand? Explain.
Directions: 1. Pick up a handout and a calculator;
2. Copy the warm-up question to your journal and answer in complete sentences.
How much energy must be added to a bowl of
125 popcorn kernels
in order for them to reach a popping temperature of
175℃
?

Assume that their initial temperature is
21℃
, that the specific heat capacity of popcorn is
1650 J/(kg.℃)
, and that each kernel has a mass of
0.105g
The initial temperature o 0.150 kg of ethanol was 22℃. What will be the final temperature of the ethanol if 3240 J was needed to raise the temperature of the ethanol?

Specific heat capacity of ethanol is 2440 J/(kg.℃)
Specific Heat Capacity
Demonstration of the Warm-up Activity
Exit Quiz!
216 J of heat energy is required to raise the temperature of aluminum from 15℃ to 35℃. Calculate the mass of aluminum.

Specific heat capacity of aluminum is 900 J/(kg.℃)
Some things
heat up
or
cool down
faster than others
Sand heats up and cools down faster than water
Review: Heat vs. Temperature
Heat:
flow of energy from hotter objects to cooler objects

Temperature:
a measure of the average kinetic energy of the molecules of an object
Post-demo questions:

Record the initial and final temperatures of the aluminum cube and the water.

Do you think the objects absorbed different amounts of heat despite being on the same hot plate?
Introduction
You can think of heat capacity as a measure of the heat energy something can hold
UNITS
for heat capacity:
J / ℃
Specific Heat Capacity Formulas
Q

= heat energy transferred ( J)
m
= mass (kg)
c

= specific heat constant [ J/(kg.℃)]
∆T
= change in temperature (℃ or K)
for specific heat capacity:
What is the sign of
∆T
when heat is
transferred

to the object?
What is the sign of
∆T
when heat is
removed from the object?
When
Q
is positive,
∆T
is positive,
and when
Q
is negative,
∆T
is negative!
J /(kg.℃)
The amount of heat energy required to raise the temperature of 1 kg of a certain material by 1℃
Problem Solving!
Concept Question:
Ethyl alcohol has about one-half of the specific heat capacity of water. If equal masses of alcohol and water in separate beakers at the same initial temperature are supplied with the same amount of energy, which will have the higher final temperature?
a
calorimeter
is used to help measure the specific heat of a substance
5
Student Practice!
Don't forget to convert g to kg!
Heat capacity
is the amount of heat energy required to raise the temperature of a certain material by 1˚C
Specific heat capacity
is the amount of heat energy required to raise the temperature of 1 kg of a certain material by 1℃
A
calorimeter
is used to help measure the specific heat of a substance
UNITS
mass of aluminum = _________
specific heat capacity of aluminum = 900 J/(kg.℃)
initial temperature of aluminum = _________
final temperature of aluminum = __________
mass of water = _________
specific heat capacity of water = 4186 J/(kg.℃)
initial temperature of water = _________
final temperature of water = __________
Applying the formula:
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