CEM 141 FINAL EXAM QUESTIONS
WITH CORRECT ANSWERS
When gas molecules collide, why don't they stick together? - Answer-they have so
much energy that they overcome attractive forces that would keep them together (you
would need another particle to collide with them to remove energy from the system to
get them to stick)
Why don't we smell substances immediately after they are released? - Answer-because
of Brownian motion (collisions make the gases move slower because it prevents travel
in a straight line)
What are the forms of movement? - Answer--translation (normally associated with KE)
-rotation
-vibration
What is thermal energy? - Answer-energy associated with motion of particles
What is heat? - Answer-the transfer of thermal energy by way of collisions
What is specific heat capacity? - Answer-the energy it takes to change the temperature
of 1 gram of a substance by 1 degree Celsius or 1 K
What is molar heat capacity? - Answer-the energy required to raise 1 mol of a
substance 1 degree Celsius or K
If you add the same amount of thermal energy to 1 gram of several different
substances, which one would increase in temperature the most? - Answer-the one with
the lowest specific heat capacity because it takes less energy to raise its temp
Why does it take more energy to raise the temp of a liquid compared to a gas? -
Answer-because liquids still need energy to overcome their IMFs but gases simply use
that energy to increase the temp
What happens to the temp at a phase change? - Answer-it stays constant because the
thermal energy that's added is being used to break IMFs, not raise the temp
What's an open system? - Answer-a system that can transfer matter and energy
What's a closed system? - Answer-a system that can transfer energy but not matter
,What's an isolated system? - Answer-no transfer of anything
What is a state function? - Answer--a function that only depends on the initial and final
states of the system (doesn't care about the path taken)
-denoted by uppercase letters
What is a path function? - Answer--a function that depends on how the reaction was
achieved
-denoted by lowercase letters
What is internal energy? - Answer-a state function that adds up all the KE and PE of the
particles in the system
What's the first law of thermodynamics? - Answer-energy cannot be created/destroyed
but it can be transferred or transformed
Is there such a thing as a "scientific method?" - Answer-no
What do scientists do? - Answer-1. ask questions
2. design experiments
3. gather/analyze data and evidence
4. make claims (based on the data/evidence)
5. develop models, explanations, and theories about how/why the universe behaves as
it does
How can scientific questions be answered? - Answer--doing experiments
-making observations
-taking measurements
-it must be replicable
What makes something not science? - Answer-if an experiment can't be replicated
reliably, then it's not science
What do you need when you make a claim? - Answer-you need evidence to support it
and maybe even a model
What is a scientific model? - Answer-it can be a drawing, graph, diagram, or equation
that's physical/mental
What are models used for? - Answer--explain how things happen
-make testable, quantifiable predictions
What do we do with our claims, evidence, and data? - Answer-we develop an
explanation/scientific theory to help us explain why these things happen
, What should scientists aim for? - Answer-the most complete set of ideas we can come
up with
How do you create a scientific explanation? - Answer-1. Claim: the target of your
explanation
2. Evidence: data/scientific principle you are using to support your claim
3. Reasoning: connection between your claim and evidence
What is a scientific theory? - Answer-the best available explanation of the existing
evidence/data/observations
What are the characteristics of a good scientific theory? - Answer--explains how/why
something happens
-makes testable predictions
-is falsifiable
-may change over time as new evidence is uncovered
What's the difference between a law and a theory? - Answer-a law describes the
phenomenon (so it tells you what happens); a theory explains the phenomenon (so it
tells you why it happens)
Which has atoms in it? Heat, cells, air, or gold? - Answer-cells, air, and gold
How big do you think an H atom is? - Answer-about 0.1 nanometer
How do we know atoms exist/ what's the evidence? - Answer-we can actually "see"
them
What are the two methods that allow us to see things at the atomic level? - Answer-
atomic force microscopy (AFM) and scanning tunneling microscopy (STM)
Where did the original idea for atoms come from? - Answer-the Greeks ("atomos"- not
to be cut)
What were some of the Greeks most prominent ideas about atoms? - Answer--based on
philosophy
-based on the elements
-thought atoms were in constant motion with a "void" between them (Brownian motion)
What was important about how the Greeks theorized atoms were shaped? - Answer-it
foreshadowed the idea that the atomic/ molecular structure of a substance determines
its observable properties
What keeps atoms in constant motion? - Answer-thermal energy
What differentiates one atom from another? - Answer-the number of protons it has
WITH CORRECT ANSWERS
When gas molecules collide, why don't they stick together? - Answer-they have so
much energy that they overcome attractive forces that would keep them together (you
would need another particle to collide with them to remove energy from the system to
get them to stick)
Why don't we smell substances immediately after they are released? - Answer-because
of Brownian motion (collisions make the gases move slower because it prevents travel
in a straight line)
What are the forms of movement? - Answer--translation (normally associated with KE)
-rotation
-vibration
What is thermal energy? - Answer-energy associated with motion of particles
What is heat? - Answer-the transfer of thermal energy by way of collisions
What is specific heat capacity? - Answer-the energy it takes to change the temperature
of 1 gram of a substance by 1 degree Celsius or 1 K
What is molar heat capacity? - Answer-the energy required to raise 1 mol of a
substance 1 degree Celsius or K
If you add the same amount of thermal energy to 1 gram of several different
substances, which one would increase in temperature the most? - Answer-the one with
the lowest specific heat capacity because it takes less energy to raise its temp
Why does it take more energy to raise the temp of a liquid compared to a gas? -
Answer-because liquids still need energy to overcome their IMFs but gases simply use
that energy to increase the temp
What happens to the temp at a phase change? - Answer-it stays constant because the
thermal energy that's added is being used to break IMFs, not raise the temp
What's an open system? - Answer-a system that can transfer matter and energy
What's a closed system? - Answer-a system that can transfer energy but not matter
,What's an isolated system? - Answer-no transfer of anything
What is a state function? - Answer--a function that only depends on the initial and final
states of the system (doesn't care about the path taken)
-denoted by uppercase letters
What is a path function? - Answer--a function that depends on how the reaction was
achieved
-denoted by lowercase letters
What is internal energy? - Answer-a state function that adds up all the KE and PE of the
particles in the system
What's the first law of thermodynamics? - Answer-energy cannot be created/destroyed
but it can be transferred or transformed
Is there such a thing as a "scientific method?" - Answer-no
What do scientists do? - Answer-1. ask questions
2. design experiments
3. gather/analyze data and evidence
4. make claims (based on the data/evidence)
5. develop models, explanations, and theories about how/why the universe behaves as
it does
How can scientific questions be answered? - Answer--doing experiments
-making observations
-taking measurements
-it must be replicable
What makes something not science? - Answer-if an experiment can't be replicated
reliably, then it's not science
What do you need when you make a claim? - Answer-you need evidence to support it
and maybe even a model
What is a scientific model? - Answer-it can be a drawing, graph, diagram, or equation
that's physical/mental
What are models used for? - Answer--explain how things happen
-make testable, quantifiable predictions
What do we do with our claims, evidence, and data? - Answer-we develop an
explanation/scientific theory to help us explain why these things happen
, What should scientists aim for? - Answer-the most complete set of ideas we can come
up with
How do you create a scientific explanation? - Answer-1. Claim: the target of your
explanation
2. Evidence: data/scientific principle you are using to support your claim
3. Reasoning: connection between your claim and evidence
What is a scientific theory? - Answer-the best available explanation of the existing
evidence/data/observations
What are the characteristics of a good scientific theory? - Answer--explains how/why
something happens
-makes testable predictions
-is falsifiable
-may change over time as new evidence is uncovered
What's the difference between a law and a theory? - Answer-a law describes the
phenomenon (so it tells you what happens); a theory explains the phenomenon (so it
tells you why it happens)
Which has atoms in it? Heat, cells, air, or gold? - Answer-cells, air, and gold
How big do you think an H atom is? - Answer-about 0.1 nanometer
How do we know atoms exist/ what's the evidence? - Answer-we can actually "see"
them
What are the two methods that allow us to see things at the atomic level? - Answer-
atomic force microscopy (AFM) and scanning tunneling microscopy (STM)
Where did the original idea for atoms come from? - Answer-the Greeks ("atomos"- not
to be cut)
What were some of the Greeks most prominent ideas about atoms? - Answer--based on
philosophy
-based on the elements
-thought atoms were in constant motion with a "void" between them (Brownian motion)
What was important about how the Greeks theorized atoms were shaped? - Answer-it
foreshadowed the idea that the atomic/ molecular structure of a substance determines
its observable properties
What keeps atoms in constant motion? - Answer-thermal energy
What differentiates one atom from another? - Answer-the number of protons it has
