Unit 4 Quiz - Heat of Physical Changes

First law of thermodynamics

states the total energy in the universe is constant(energy is conserved)

Increase in potential energy(PE)

more conflict between particles due to arrangement, less stability

Decrease in potential energy(PE)

less conflict between particles due to arrangement, more stability

Endothermic Reaction

when energy is gained by the system, but lost by the surroundings(+q system = -q surroundings)

Exothermic reaction

when energy is lost by the system and gained by the surroundings(-q system = +q surroundings)

enthalpy of reaction is the same thing as

delta H

Second law of thermodynamics

states that energy prefers to move in “favorable” direction(high to low)

What is thermal equilibrium?

When all particles have the same KE

What happens when you add energy to the system(energy goes from surroundings to system)?

+KE, +delta T, if a phase change then + PE,+ delta H, and the process is overall endothermic

What happens when you remove energy from the system(energy goes from system to surroundings)?

- KE, -delta T, - delta PE, -delta H, and the process is exothermic

When do you use q=mc * delta T

when there is no phase change, and you are simply heating or cooling a substance

When do you use q=m * delta H

When a phase change is occurring(will use delta H fusion or vaporization depending on the change)

measurement of melting or freezing phase change

± delta H fusion

measurement for vaporization or condensation phase change

± delta H vaporization

delta T =

T final of solution - T initial of water/container

What is absolute zero?

zero kelvin