1. Heat
In this chapter, you will further understand
heat, temperature, and thermal energy. You will
learn about the different effects of heat on
matter, particularly on its effects on phase
changes and thermal expansion of matter.
2. Whenever you use the thermometer to take your
temperature, why do you have to wait for a few minutes
before you check its reading? Temperature is the average
kinetic energy of a system. For example, when you boil water,
the particles of the water would have different kinetic
energies. The kinetic energy of the particles near the source of
the heat is different from the kinetic energy of the particles
near the surface. So, to get the temperature of the water you
need to know the average kinetic energy of all the particles.
This also means that the number of particles does not affect
the temperature of a system. So, what happens when we sum
up all the kinetic energies and potential energies of a system?
We get the thermal energy of the system.
3. Internal energy – refers to the total
amount of kinetic energy and potential
energy in the system.
Thermal energy – it is the total energy of
the system responsible for its
temperature.
4. Thermal energy depends on the amount
of the substance. The greater the amount
of the substance, the greater the thermal
energy.
Temperature is the average kinetic energy
in a system. So, it does not depend on
the amount of substance.
5. Unlike temperature, thermal energy depends on the amount of
matter. This means that the more particles a system has, the more
thermal energy it possesses. So, a 500 mL water at 70 °C has more
thermal energy than a 100 mL water with the same temperature.
Temperature can be measured in Celsius, Fahrenheit, kelvin, and
Rankine (relating to an absolute-temperature scale on which the unit of
measurement equals a Fahrenheit degree and on which the freezing
point of water is 491.67° and the boiling point 671.67). The Philippines
and other Asian countries use degrees Celsius. In other countries, they
use degrees Fahrenheit. Kelvin on the other hand is the SI unit of
temperature.
If two bodies with different temperatures come in contact with
each other, you will notice that they will eventually end up with the
same temperature.
6. Heat is defined as energy transit. It is a type of
energy that transfers from one body to another
whether there is a difference in temperatures. Heat is
measured in joules (J).
If there is no temperature difference, there will be no
heat transfer.
Hotter objects tend to give off heat. Heat flows from
hotter bodies or objects to colder ones. If you hold an
ice cube with your bare hand, the heat from your
hand transfers to the ice cube causing it to melt. The
transfer of heat from your hand makes your hand
feels cold.
7. If there is no temperature difference there will be no heat transfer.
Hotter objects stops from giving off heat when both objects
reach thermal equilibrium. The first object is initially at 0°C, and
the other is at
100 °C. when the two objects are placed in contact with each
other in a closed system, the final temperature becomes 50 °C.
Anders Celsius- is a Swedish astronomer from Uppsala, Sweden.
He invented a temperature scale that was named after him- the
Celsius. This temperature scale is also known as the centigrade
scale. Under the Celsius scale, the freezing point of water is 0 °C,
and its boiling point is 100 °C.
8. Five Phases of Matter
1. Solid
2. Liquid
3. Gas
4. Plasma
5. Bose-Einstein condensate
During a phase change, the temperature of a system remains constant.
This means that the added heat to the system is used to change the phase of
the system and not to increase its temperature.
If a solid is converted directly to gas without passing the liquid phase it
is called sublimation.
If a gas is converted directly to a solid without passing the liquid phase,
it is called deposition.
10. Quiz 2.3 - Heat
Direction: Choose the letter of the correct answer.
1. It is the average kinetic energy of a system.
A.) Degrees B.) Celsius C.) Temperature D.) Kelvin
Ans. C
2. It refers to the total amount of kinetic energy and
potential energy in the system.
A.) Internal Energy C.)Kinetic Energy
B.) Thermal Energy D.) Ohm’s law
11. 3. It is the total energy of the system responsible for
its temperature.
A.) Internal Energy C.) Kinetic Energy
B.) Thermal Energy D.) Ohm’s law Ans
a. . B
4. It depends on the amount of the substance.
A.) Internal Energy C.) Kinetic Energy
B.) Thermal Energy D.) Ohm’s law Ans. B
12. 5. It is defined as energy in transit.
A.) Heat C.) Temperature
B.) Joules D.) Energy
Ans. A
6. Heat is measured in ______.
A.) Newton C.) Joules
B.) Degrees D.) Celsius Ans. C.
13. Ans. C.
7. What is the freezing point of water?
A.) 90°C B.) 80°C C.) 100°C D.) 0°C
Ans. D
8. What is the boiling point of water?
A.) 0°C B.) 90°C C.) 100°C D.) 50°CAns. C
14. 9. If a solid is converted directly to gas without
passing the liquid phase it is called _______.
A.) Preposition C.) Disposition
B.) Sublimation D.) Absorption Ans.B
10. If a gas is converted directly to a solid
without passing the liquid phase, it is called
________.
A.) Preposition C.) Deposition
B.) Sublimation D.) Absorption Ans.C
15. Give the five STATES/PHASES of MATTER
11. Solid
12. Liquid
13. Gas
14. Plasma
15. Bose-Einstein condensate
