THERMOCHEMISTRY (PART 1) Flashcards
1
Q
- What is energy?
A
- it is the capacity to supply heat
- it is the capacity to do work
2
Q
- What are the two basic types of Energy?
A
- Kinetic Energy
- Potential Energy
3
Q
- What is Kinetic Energy?
A
- this is the energy of motion
4
Q
- What is Potential Energy?
A
- this is the stored energy
- it is the potential to do work
5
Q
- What are some examples of Potential Energy?
A
- gravitational energy
- elastic energy
- electromagnetic energy
- nuclear energy
- chemical energy
- mechanical energy
- thermal energy
6
Q
- 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
7
Q
- 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
8
Q
- How do we mathematically calculate Gravitational Potential Energy?
A
9
Q
- 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
10
Q
- 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
11
Q
- 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
12
Q
- 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
13
Q
- 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
14
Q
- 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
15
Q
- 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
16
Q
- 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
- 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
- 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
- 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
- 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
- What is a System?
A
- this is one we choose to study
22
Q
- What are Surroundings?
A
- this is everything else in the Universe
23
Q
- What is the Boundary?
A
- this is the border between the system and the
surroundings
24
Q
- 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
25. What are the types of Thermodynamic Systems?
1. Isolated System
2. Closed System
3. Open System
26
26. What is an Isolated System?
- a system in which there is no exchange of matter or
energy
- no material or heat can enter of exit the system
27
27. Why does a Thermos Flask stay cold for a long time when we put cold water into it?
- the region of the vacuum is around the inner container
- this prevents the heat from entering the flask through
conduction
28
28. Why does a Thermos Flask stay warm for a long time when we put hot water into it?
- 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
29. Can heat energy be exchanged with the surroundings?
- 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
30. What is a Closed System?
- this is a system in which there is. no exchange of
matter
- energy can pass through
- heat can exit or enter this can
31
31. What happens if the coke remains closed?
- matter cannot exit or enter the can
- heat energy can enter the can
- it can also leave the can
32
32. What happens if we put the coke in the refrigerator?
- 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
33. Can heat energy be exchanged with the surroundings of the system?
- heat can enter or exit the can
- matter cannot enter or exit the can
- this is known as a Closed System
34
34. What is an Open System?
- a system in which the exchange of gas and energy are
possible
- matter and heat can enter and exit the system
35
35. What is a result of the Coke can being an Open System?
- 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
36. What happens if we place a glass of Coke in the Refrigerator?
- the Coke will lose Heat Energy
- the Coke will cool down even further
37
37. What happens if we place a glass of Coke in Room Temperature?
- 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
38. What kind of system would this be?
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
