Honors Chemistry B - Thermodynamics Flashcards

welcome 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

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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?