Studied by 25 peoplewelcome honors chem students! this is a collection of general info and tips to study for the test :)
kinetic energy
energy associated with movement
true or false: higher speed of particles → higher kinetic energy
TRUEEEE
true or false: lower temperature → higher kinetic energy
FALSE
what is potential energy?
stored energy
or if u want to be fancy, “energy due to position”
temperature
the measure of kinetic energy
heat
transfer of energy due to temperature difference
specific heat
the energy needed to raise the temperature of 1 gram of a substance by 1 degree Celsius
enthalpy
the energy that is either released or absorbed in a process
qualities of a solid
high molecular attraction
compact
shaking
low energy
rigid
fixed shape
fixed volume
cannot be squased
qualities of a liquid
basically just mid.
mid molecular attraction
mid energy
molecules flowing past each other
loosely packed
not rigid
no fixed shape
fixed volume
cannot be squashed…ig
qualities of a gas
little speedsters
molecules move quickly
high energy
low molecular attraction (that’s why they zoom)
CAN be squashed :D
true or false: the higher the energy, the lower the attraction between the molecules
true
why doesn’t a substance change temperature while it is melting?
energy as heat is being used to melt the substance, however, it takes a significant amount of energy to break the intermolecular forces to phase change
so all of the energy is being focused on phase-changing the substance instead of raising its temperature
what does it mean when a reaction is exothermic?
it means that heat is released
as result of heat/energy being released outward, it will feel warm
reactants have more energy than the products
energy is written on the products side
ie: CH4+2O→ 2H2O + 802.2kJ/mol
what does it mean when a reaction is endothermic?
it means that heat is being absorbed
feels cold
products have more energy than the reactants
energy is written on the reactants side
N2+O2+298 kJ/mol → 2NO (not real example, just shows the formatting)
The enthalpy (Delta H) of a reaction is found to be -5223 calories, is the reaction endothermic or exothermic?
exothermic, the number is negative, so heat is being released
when a substance is dissolved in water, the beaker containing the solution becomes cold, is the reaction endothermic or exothermic?
endothermic, the beaker turning cold is a sign that the heat is being absorbed into the substance, meaning the reaction is endothermic
when do you use the q=mcat (pretend “a” is a triangle) formula?
when changing the temperature of a substance
when would you use the q=mah (pretend “a” is a triangle) formula?
when phase changing a substance
why would steam burn your hand more severely than water?
steam has more energy than water, and would release more energy as it condenses when it touches your hand…magic
fun little practice question: aluminum solid has a specific heat of 0.897 J/g degrees Celsius, what mass of Aluminum can be warmed from 52-100 degrees Celsius by absorbing 300 J of energy?
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