Unit 4 Test Flashcards
Energy
Ability of object or system to do work
Heat
Energy that transfers from one object to another because of a temperature difference between the objects
Why does matter not contain heat?
Heat is a form of energy and is an ability, so you cannot contain heat.
What are different types of energy?
Thermal, chemical, electrical, electricochemical, electromagnetic, nuclear, mechanical, kinetic, and potential
What is potential energy?
Stored energy because position relative to another object
Potential to do work
Examples: trampoline, stretched rubber band, and bow and arrow
What is gravitational potential energy?
roller coaster or ball
What is kinetic energy?
Energy resulting from motion
What is kinetic energy’s relationship with speed?
When speed doubles, kinetic energy quadruples.
What is the Law of Conservation of Energy?
Within a closed system, energy can not be created or destroyed; it may be transformed from one form to another, but total energy stays the same.
What are the steps to solve a roller coaster problem?
- ) Find TE at whatever point you can solve potential and kinetic energy.
- ) TE is the same throughout the coaster.
- ) Solve for the unknowns.
What is the purpose of work?
to move things
work
ability to move or cause change because of the force exerted over a distance (force and distance in the same direction)
What is power?
The amount of work done per time it takes to do it
What is matter?
The material that makes up the universe including mass and space, or volume.
What are the different states or phases?
Solid, liquid, and gas
What is the solid phase?
The molecules are rigid, close together, and there is a definite shape and volume.
What is the liquid phase?
The molecules are close, move more, indefinite shape, but definite volume.
What is the gas state?
The molecules are far apart, move freely, and indefinite shape and volume.
What are physical properties?
measured without changing chemical nature of the substance
What are chemical properties?
Measured by changing chemical nature of the substance
What is an element?
simplest form of matter that has a unique set of properites
Compound
substance contains two or more elements chemically combined in a fixed proportion
Homogeneous mixtures
uniform througout
Heterogeneous Mixtures
not uniform throughout
What is temperature?
measure of how hot something is compared to a standard
average kinetic energy of the molecules in a substance
can twist, vibrate, and rotate
When does potential energy increase and decrease?
when the bonds break the energy goes up, and when the bonds form the energy goes down
What is specific heat?
quality of heat required to change the temperature of a substance one degree celsius
What is evaporation?
liquid to gas that takes place on surface of liquid only
only molecules with most kinetic energy change into gas
cooling process because less energy left in remaining liquid
condensation
gas to liquid
warming process because energy increases
Boiling
phase change from liquid to gas
throughout liquid
cooling process because heat added
Why is it harder to boil water or bake things at high altitudes?
The decrease in pressure only lets water get to a certain temperature.
Are melting and freezing points the same?
yes
Condensing and boiling points the same?
yes
What is an alloy?
metal made by combining two or more elements
What is different between pure substances and mixtures?
Pure substances only have only one phase and mixtures have more than one.
What are some indications of chemical change?
light, heat, color change, gas production, odor, or sound
What are some examples of physical change?
breaking a bottle, melting ice, and freezing water
What are some examples of chemical change?
burning, rusting, and cooking
What are some physical properties?
size, color, volume, and mass
During the phase change of a substance, what is happening to the potential energy?
It is changing.
How does heat flow from hot objects to cold objects?
There is not such a thing as coldness, so the hotness is taken from the object and transferred to the lower temperature object. The hot object has less heat, so it is a lower temperature, too.
Why when the energy is higher is the object hotter?
There is less room for the molecules to move around resulting in a higher temperature.
What is the plasma state?
The electrons have heated up so much that they have escaped. Positive ions are left.
What can gases do?
They can vibrate, translate, and rotate.
What can liquids do?
vibrate and rotate
What can solids do?
vibrate
Is kinetic energy proportional to temperature?
yes
What does endothermic mean?
absorbs heat
What does exothermic mean?
releases heat
Which reactions are exothermic, and which are endothermic?
exothermic- freezing, condensation, and gas to solid (deposition)
endothermic- boiling, evaporation, melting, and solid to gas (sublimation)
How is energy translated?
When potential energy goes up, kinetic energy goes down. When kinetic energy goes up, potential energy goes down. Sometimes there is friction which can become thermal energy.
