Real-World Applications
Why does concrete feel hotter than grass under the same sunlight?
What is because concrete has a lower specific heat and absorbs heat faster?
A chemical reaction releases heat into the air. What type of reaction is this?
exothermic
The transfer of thermal energy from one object to another
What is heat?
The total kinetic energy of a substance is called this.
What is thermal energy?
If a scientist is studying a beaker of water being heated on a hot plate, identify the system and surroundings.
What is the water (system) and the hot plate + air around it (surroundings)?
Why does water take so long to heat up compared to sand at the beach?
because water has a much higher specific heat capacity
unit of measurement for energy
what is joules
The direction heat flows
what is hot to less hot?
Define matter and energy
anything that has mass and takes up space
an object's capacity to do work or produce heat
Which type of system (open, closed, or isolated) best describes a sealed soda can left in the sun?
What is a closed system?
Two cups of water are at the same temperature. One has twice as much water as the other. Which cup has more thermal energy, and why?
larger more particles
heat transfer method: water mixes, eventually reaching thermal equilibrium
what is convection
Compare the average kinetic energy of particles in boiling water and steam at 100℃.
they have the same average kinetic energy because they are at the same temperature
Average kinetic energy
what is temperature
Explain why defining the system incorrectly can lead to errors in predicting energy transfer.
What is because energy flows depend on what you include/exclude as “inside” the system?
A metal spoon left in boiling soup becomes too hot to hold. Which type of heat transfer causes this?
conduction
If two substances at the same temperature are mixed and the flask feels cool to the touch, what can you conclude about the process?
the reaction is endothermic, absorbing heat from the surroundings
Why is temperature not a direct measure of the total thermal energy of a substance?
What is because temperature measures average particle energy, while thermal energy depends on mass and number of particles too?
What kind of energy is stored in the bonds of molecules? (aka energy of position)
What is potential energy?
A student measures the mass of a burning candle and notes that it decreases. Why does this not violate conservation of mass?
What is because gases (CO₂, H₂O vapor) escape into the surroundings?
Why does metal feel colder than wood on days when the temperature is low?
because metal is a conductor and transfers heat away from your hand quickly
If 100 mL of water at different temperatures are mixed, where will thermal equilibrium be reached?
in the middle
Explain the fact that cold doesn't exist
what is there is only hot and less hot, if something feels cold to the touch that means you are releasing heat
Why does a moving truck have more kinetic energy than a moving bicycle at the same speed?
What is because the truck has more particles
the reason an endothermic reaction feels cold
you are the surroundings. as you lose heat the reaction gains heat