THERMOCHEMISTRY (PART 1) Flashcards

1
Q
  1. What is energy?
A
  • it is the capacity to supply heat
  • it is the capacity to do work
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2
Q
  1. What are the two basic types of Energy?
A
  1. Kinetic Energy
  2. Potential Energy
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3
Q
  1. What is Kinetic Energy?
A
  • this is the energy of motion
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4
Q
  1. What is Potential Energy?
A
  • this is the stored energy
  • it is the potential to do work
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5
Q
  1. What are some examples of Potential Energy?
A
  • gravitational energy
  • elastic energy
  • electromagnetic energy
  • nuclear energy
  • chemical energy
  • mechanical energy
  • thermal energy
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6
Q
  1. What does Mechanical Energy equate to?
A

Kinetic Energy + Potential Energy = constant

THIS MEANS THAT:
- an increase in kinetic energy results in a decrease in
potential energy
- this is true for an isolated system and vice versa

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7
Q
  1. What is the First Law of Thermodynamics?
A
  • it is also known as the Law of Conservation of Energy
  • energy is neither created nor destroyed
  • this energy can be converted from one form to another
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8
Q
  1. How do we mathematically calculate Gravitational Potential Energy?
A
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9
Q
  1. How is a Roller Coaster an example of the First Law of Thermodynamics?
A
  • the system is isolated
  • the Mechanical Energy is conserved and kept constant
  • an increase in the Gravitational Potential Energy of
    the system results in a decrease in the Kinetic Energy
    of the system

WHEN THE ROLLER COASTER IS AT MAXIMUM SPEED:
- the potential energy is at it’s minimum

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10
Q
  1. What happens to the other energies present in the system when the Roller Coaster is at Maximum Height?
A
  • the potential energy is at a maximum
  • the kinetic energy is at its minimum
  • the roller coaster is moving very slowly
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11
Q
  1. What happens to the energies in the system when the Roller Coaster starts moving downwards?
A
  • the potential energy decreases
  • the heigh decreases
  • the speed picks up
  • the kinetic energy increases
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12
Q
  1. What happens to the energies in the system when the Roller Coaster reaches its lowest?
A
  • the kinetic energy is maximised
  • the potential energy is minimised
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13
Q
  1. What happens to the energies in the system when the Roller Coaster starts climbing again?
A
  • the speed decreases
  • the kinetic energy drops
  • the height increases
  • the potential energy increases
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14
Q
  1. What happens to the energies in the system at all the points in the Roller Coaster?
A
  • the sum of the potential and the kinetic energies is
    constant
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15
Q
  1. How does a Thermometer work?
A
  • the air molecules collide with the bulb
  • the heat is created from the collisions
  • the liquid in the bulb expands when heated
  • this allows for you to read the temperature
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16
Q
  1. What happens when the temperature rises in the air around the thermometer?
A
  • the air molecules move faster
  • the particles collide more frequently
  • the particles collide with the thermometer bulb with
    more intensity
  • this creates more heat
  • this causes the liquid to expand
  • the thermometer reads as a higher temperature
17
Q
  1. What is Chemical Energy?
A
  • the energy needed to break the bonds between
    particles
  • these particles are held together by attractive forces
  • this is an endothermic reaction
18
Q
  1. Is forming a Chemical Bond an endothermic or an exothermic reaction?
A
  • Exothermic
  • heat is given out
  • heat is released to the environment
  • this is when bonds are made
19
Q
  1. What kind of Chemical Reaction happens when Bonds are broken?
A
  • bond breaking needs energy
  • the nuclei are kept in place by the attraction of the
    central electrons
  • energy input is needed to pull these electrons away
  • this will break the bond
20
Q
  1. What is an Explosion?
A
  • this is the very rapid production of heat
  • the production of large amounts of gases
  • the gases are expanding into the environment
  • it is a reaction that does work
21
Q
  1. What is a System?
A
  • this is one we choose to study
22
Q
  1. What are Surroundings?
A
  • this is everything else in the Universe
23
Q
  1. What is the Boundary?
A
  • this is the border between the system and the
    surroundings
24
Q
  1. What is the relation between the system and the surroundings?
A
  • whatever happens to the system is the opposite of
    what will happen to the surroundings
25
Q
  1. What are the types of Thermodynamic Systems?
A
  1. Isolated System
  2. Closed System
  3. Open System
26
Q
  1. What is an Isolated System?
A
  • a system in which there is no exchange of matter or
    energy
  • no material or heat can enter of exit the system
27
Q
  1. Why does a Thermos Flask stay cold for a long time when we put cold water into it?
A
  • the region of the vacuum is around the inner container
  • this prevents the heat from entering the flask through
    conduction
28
Q
  1. Why does a Thermos Flask stay warm for a long time when we put hot water into it?
A
  • the inner walls are silvered
  • these walls reflect the heat of the water back into the
    flask
  • the vacuum region surrounding the inner container of
    the thermos flask will not allow the heat to escape
    to the outside
29
Q
  1. Can heat energy be exchanged with the surroundings?
A
  • no
  • heat energy cannot exit or enter
  • the flask top is closed
  • no matter can enter or exit the thermos flask
  • the system is completely isolated
30
Q
  1. What is a Closed System?
A
  • this is a system in which there is. no exchange of
    matter
  • energy can pass through
  • heat can exit or enter this can
31
Q
  1. What happens if the coke remains closed?
A
  • matter cannot exit or enter the can
  • heat energy can enter the can
  • it can also leave the can
32
Q
  1. What happens if we put the coke in the refrigerator?
A
  • the heat leaves the can contents
  • the heat goes inside the refrigerator
  • the can and its contents cool down
  • this is because the metal of the can is a good
    conductor of heat
33
Q
  1. Can heat energy be exchanged with the surroundings of the system?
A
  • heat can enter or exit the can
  • matter cannot enter or exit the can
  • this is known as a Closed System
34
Q
  1. What is an Open System?
A
  • a system in which the exchange of gas and energy are
    possible
  • matter and heat can enter and exit the system
35
Q
  1. What is a result of the Coke can being an Open System?
A
  • the liquid is evaporating very slowly
  • the Coke is loosing Carbon Dioxide gas
  • the CO2 bubbles are rising to the surface

MORE COKE CAN ALSO BE POURED INTO THE GLASS:
- the exchange of matter is possible

36
Q
  1. What happens if we place a glass of Coke in the Refrigerator?
A
  • the Coke will lose Heat Energy
  • the Coke will cool down even further
37
Q
  1. What happens if we place a glass of Coke in Room Temperature?
A
  • the Coke will gradually warm up
  • the Coke will reach Room temperature
  • the heat is entering the system
  • both matter and heat can exit the system
38
Q
  1. What kind of system would this be?
A

CLOSED SYSTEM:
- the lid on the cup ensures that there will be no
exchange of matter with the surroundings
- energy will be exchanged
- the coffee inside the cup will gradually become colder
- this is because heat is lost to the surroundings