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
Q
- What are the types of Thermodynamic Systems?
A
- Isolated System
- Closed System
- Open System
26
Q
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
