Temperature and Heat
Watch It Spread



Overview
For this introductory activity you will observe food coloring after it is placed into water
of various temperatures.
Hypothesis: ?
Materials:

food coloring

three 250 mL beakers

water of various temperatures (hot, room temperature, cold)

clock/timer

data table
Procedures:
1.
Write a hypothesis on the back of your data table.
2.
Label the beakers and fill them with 100 mL of hot, room temperature, and cold
water.
3.
Place a drop of food coloring into each of the beakers.
4.
Each member of the group should rate how much the food coloring has diffused in
the beaker over a ten minute period of time:
5.
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1 = small amount (≈1-33%)
2 = medium amount (≈33-67%)
3 = large amount (≈67-100%).
Average your results and create a line graph of your average data with the rating
on the y-axis and the timed intervals on the x-axis.
Do not touch/move the beakers once the water and food coloring are in them.
Data Table
Member
1
2
3
4
5
Average
2 Minutes
4 Minutes
6 Minutes
8 Minutes
10 Minutes
H
H
H
H
H
R
C
R
C
R
C
R
C
R
C
Discussion Questions
1. What patterns or trends did you
notice?
2. What factors could have impacted the
accuracy of your data?
3. Did your data support your hypothesis?
Explain your reasoning.
Kinetic Theory of Matter
 states that all of the
particles that make up
matter are constantly in
motion  all particles in
matter have kinetic energy
 energy is transferred when
particles collide with one
another
 helps explain the different
states of matter
 PhET
What do you think happens
when a slow moving particle
is struck by a fast moving one?
Temperature
 the quantity that tells how hot or cold something
is compared to a standard
 the average kinetic energy of all the particles in
an object  not determined by how much of a
substance you have
 Higher average kinetic energy (particle
movement) results in higher temperatures, while
lower average kinetic energy (particle movement)
results in lower temperatures
 measured using a thermometer
Thermometer
 an instrument for measuring temperature
 typically a thin glass tube filled with a liquid
(alcohol or mercury)
 mercury is not typically used anymore because
of its impact on the environment
 works because of thermal expansion
 consist of three different scales:
 Fahrenheit (0F)
 Celsius (0C)
 Kelvin (K)
Why is alcohol used in
thermometers instead
of water?
Temperature Scales
Water
boils
2120
1000
Which scale is being
represented by each
thermometer?
373
Room
temperature
680
200
293
Water
freezes
320
00
273
Fahrenheit
Celsius
Kelvin
The
Kelvin
scale
does not
have
negative
numbers
Converting Between Scales
 Celsius to Fahrenheit
0F
= 9 x 0C + 32
5
50C  0F
Example
 Fahrenheit to Celsius
0C
= 5 x (0F - 32)
9
700F  0C
Example
 Celsius to Kelvin
K = 0C + 273
= K - 273
0F 0F- 32)
210C = 5 x (70
9
100C  K
Example
 Kelvin to Celsius
0C
0C + 32
410F = 9 x 50C
5
0C
0C
283K
K = 10
+ 273
100 K  0C
Example
-1730C = 100
K K - 273
Combining Different Temperatures
Overview
For this activity you will mix different amounts of hot and cold water.
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Materials:
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3 - 250 mL beakers
2 - 100 mL graduated cylinder
three Celsius thermometers
hot and cold water
Procedures:
1.
2.
3.
4.
5.
6.
Label the three beakers (H, C, M).
Using the graduated cylinder, measure the amount of cold water specified
by the data table and pour it into the beaker labeled “C.” Measure and
record the temperature.
Using the graduated cylinder, measure the amount of hot water specified by
the table and pour it into the beaker labeled “H.” Measure and record the
temperature.
Predict what the temperature will be after combining the beakers.
Pour the hot and cold water into the beaker labeled “M.” Measure and
record the water temperature.
Repeat steps 2-5 for the remaining mixtures specified by the data table.
Data Table
Mixture
100 mL hot;
100 mL cold
50 mL hot;
150 mL cold
150 mL hot;
50 mL cold
Hot Water
Temperature
(0C)
Cold Water
Temperature
(0C)
Predicted
Mixed
Temperature
(0C)
Actual Mixed
Temperature
(0C)
Questions
1.
2.
3.
4.
5.
6.
7.
8.
How does the temperature of the different mixtures compare
to the original temperatures of the water?
For which mixture did your prediction come closest?
For which mixture was your prediction farthest off?
Could the temperature of the mixture (hot and cold) ever reach
the temperature of the hot or cold water? Explain your
reasoning.
Although the hot water was the same temperature in each
beaker, the impact observed when it was combined with the
cold water varied. Why did they all have a different effect?
What factors could have impacted the accuracy of your data?
What did you learn about mixing temperatures from this
activity?
What would you predict the temperature to be if 200 mL of
hot water (≈1000C) is mixed with 50 mL of cold water (≈00C) ?
Explain your reasoning.
Heating and Cooling a Metal Strip
1.
2.
3.
4.
5.
6.
7.
Plug in the hot plate and allow it to heat up for 3-5
minutes.
Have a conversation with the members of your group
regarding what you think will happen once you heat and
cool the metal strip.
Using the hot plate, heat the metal strip with the printed
side facing upward. It is not necessary to touch the
metal strip on the hot plate.
Take note of what you observe as the metal strip is
heated with the hot plate.
Allow the strip to cool for a few minutes.
Gently rub the metal strip on an ice cube with the printed
side facing upward.
Take note of what you observe as the metal strip is being
cooled with the ice.
Discussion Questions
1.
2.
3.
4.
5.
What observations did you make after putting
the metal strip over the hot plate? Be
specific!!!
Why/how did this happen?
What observations did you make after rubbing
the metal strip on the ice cube? Be specific!!!
Why/how did this happen?
What do you think would have happened if it
was heated or cooled to a greater degree?
The metal strip is actually
know as a bimetal strip.
Thermal Expansion
 the increase in volume of a substance due to an increase in
temperature – the particles themselves DO NOT expand
 as a substance gets hotter the particles move faster and
spread out
 most matter expands
when it’s
heated
As the particles
spread
out,and contracts when
it’s cooled
the volume of a substance

Exception - water
actually
expands
astoit cools from 40C to
increases.
What
happens
00C
the substance’s density?
 different substances expand at different rates
 gases generally expand or contract more than liquids, and
liquids expand or contract more than solids
 Example:
 Bimetal strips in thermostats
Thermal Expansion & Contraction
(A closer look)
Piece of
Metal
Expansion
Contraction
Applications of Thermal Expansion and
Contraction
Try to apply and/or explain the concepts of
thermal expansion and contraction as they
pertain to the following examples.
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
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expansion joints in bridges or sidewalks
thermometers
hard to open jar lid
railroad tracks and train derailments
telephone/power lines
potholes
objects filled with gas (tire, balloon, athletic ball, etc.)
What are some personal examples or experiences
with thermal expansion and contraction?
Heat
 flow or transfer of energy from an object at a higher
temperature to an object at a lower temperature, until
thermal equilibrium is reached
 matter does not have heat, it has thermal energy
 typically expressed in units of joules (J) and
calories
Why
does an (cal)
ice cube
 Calorie is really a kilocalorie and represents
foodwhile
energy
feel cold
a paper
 4.187 joules = 1 calorie
cup filled with coffee
feels hot?
 scientists believed that heat was an invisible, weightless
fluid capable of flowing caloric
 Count Rumford (Benjamin Thompson) challenged the idea
of caloric when he discovered that heat was being
produced when holes were drilled into cannon barrels
 3 types of heat transfer: conduction, convection, radiation
Boiling Water in a Paper Cup
Using the Conductometer
1. Place an equal amount of wax in the
divots of each rod (A,B,S,N,C).
2. Light the candle.
3. With the wax filled divots facing
upward, place the central heating disk
directly over the candle.
4. Observe the order in which the wax
melts.
Discussion Questions
1. What is the order in which the wax
melts.
2. What impacted how quickly the wax
melted in each rod?
3. What factors could have impacted the
accuracy of your results?
1.
2.
3.
4.
5.
Copper (C)
Aluminum (A)
Brass (B)
Steel (S)
Nickel (N)
Specific Heat Capacity
 the amount of energy needed to change the temperature of 1
kg of a substance by 10C
 how easily substances change temperatures
 increases as the size of the particles that make up the
substance increase

the higher the value  the more energy and the longer it takes
to heat up or cool down
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i.e. – with a specific heat of 0.11 cal/g0C (444 J/kg0C), nickel will
take longer to heat up and cool down compared to copper which has
a specific heat value of 0.09 cal/g0C (387 J/kg0C)
can be used to help calculate heat lost or gained by a substance
 formula: MC∆T
Explain how/why bodies of water
in our area are warmer towards
the end of the summer compared
to the beginning.
Table of Specific Heat Values
Substance
Specific Heat
(cal/g0C)
Specific Heat
(J/kg0C)
Air
0.25
1,046
Aluminum
0.22
899
Copper
0.09
387
Glass
0.20
837
Ice (-200C to 00C)
0.50
2,090
Iron
0.11
448
Mercury
0.03
138
Ocean Water
0.93
3,894
Water
1.00
4,187
Wood
0.42
1760
Thermal Energy vs. Temperature vs. Heat
Thermal Energy
Temperature
Heat
the total energy of
the particles in a
substance
a measure the average
kinetic energy of all
the particles in an
object
the transfer of
energy between
objects that are at
different
temperatures
expressed in joules
expressed in degrees
Fahrenheit, Celsius, or
Kelvin
expressed in joules or
calories
varies with the mass
and temperature of a
substance
does not vary with the
mass of a substance
varies with the mass,
specific heat capacity,
and temperature
change of a substance
Conduction
 transfer of thermal energy through a
substance, or from one substance to another
by direct contact of particles
 takes place in solids, liquids, and gases, but
takes place best in solids because the particles
of a solid are in direct contact with each other
Unfortunately for someone, after being
touched, the heat will transfer from
the iron to the hand. What are some
other real-life examples where heat is
transferred by conduction?
Conductors and Insulators
 Conductors
 substances that
conduct thermal
energy well
 particles are close
together
 different metals are
common conductors
 Insulators
 substances that do
not conduct thermal
energy well  they
delay heat transfer
 particles are far
apart
 different plastics
are common
insulators
What are some common
conductors and insulators?
Melting Blocks
Convection
 transfer of thermal energy through fluids
(liquids or gases) by means of up and down
movements called convection currents
 the circular motion of liquids or gases due to density
differences that result from temperature
differences
As the air gets heated by the flame, the
Sea and land breezes result from
particles move faster and spread out.
uneven heating of the Earth’s and
This increases the volume of the air inside
the resulting convection currents.
the balloon, which lowers the density.
Explain how this happens.
This decrease in density causes the
balloon to rise.
Radiation
 transfer of thermal (radiant) energy as
electromagnetic waves, such as visible light or
infrared waves
 energy can be transferred through matter or
empty space
 darker objects absorb more radiant energy
than lighter objects
Notice how the visible light
from the sun travels through
space and heats the Earth.
Calculating Heat – Sample Problem

How many joules are needed to raise the temperature
of 100 kilograms of copper from 10 C to 100 C? The
specific heat of copper is 387 J/kg·C.
Q = mc∆T
heat
specific
mass
change in
heat
temperature
Take the
difference
between 100C
and 1000C
Heat =(100 kg) 387 J (90 C)
kg·C
Heat = 3,483,000 J