VDLHS Honors Chemistry Unit 5 Flashcards

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Thermodynamics

study of energy/heat as it relates to matter

exothermic reaction

heat is liberated

endothermic reaction

heat is absorbed

4.185

1 calorie = ? Joules

1000

1 kilocalorie = ? calories

energy

capacity to do work

chemical energy

energy stored within structural units of compounds

thermal energy

energy associated with the random motion of particles associated with a change in temperature

potential energy

energy available by the virtue of an energy’s position

kinetic energy

energy produced by a moving object

temperature

measurement of average kinetic energy

heat

thermal energy transfer between objects in contact with each other

heat capacity

capacity of an object or substance to retain heat

higher

metals = (higher/lower) heat capacity

hot to cold

heat flows from _ to _

specific heat capacity

constant that represents the energy needed to raise the temperature of 1 gram of substance by 1°C

higher specific heat means more energy is needed to increase temperature, meaning that the temperature changes slowly because more heat must be released or absorbed

higher specific heat means (more/less) energy is needed to increase temperature, meaning that the temperature changes (slowly) because (more/less) energy must be released or absorbed

lower specific heat means less energy is needed to increase temperature, so it changes temperature quickly

lower specific heat means (less/more) energy is needed to increase temperature, so it changes temperature (slowly/quickly)

The cutting board because the ice took a longer time to melt on it

You put an ice cube on a granite countertop. At the same time, you put an ice cube on a wooden cutting board. You notice it takes the ice 3 minutes to melt on the granite and 10 minutes to melt on the cutting board. Which item has a higher specific heat? Explain your choice.

The ______ because the ice took a (longer/shorter) time to melt on it.

C

Variable for the specific heat capacity and resistance to raise the temperature when heat is provided

J / gC°

C =

q

Variable for heat

m

variable for mass of a substance

∆T

variable of temperature change

∆Tfinal - ∆Tinitial

how is ∆T calculated?

q = mC∆T

formula to calculate heat needed to change temperature of material

absorption of heat

+q means…

release of heat

-q means…

latent heat (∆H)

Constant that represents the energy absorbed or released during a constant temperature process

J/g

units for ∆H

Q = m∆H (vap/fus)

formula to determine a phase change

melting/freezing

fusion is

boiling/condensation

vapor is

ice/solid

fusion can only occur when there is …

-q, exo

Freezing = (+q or -q) (endo or exo)

+q, endo

Melting = (+q or -q) (endo or exo)

-q, exo

condensation= (+q or -q) (endo or exo)

+q, endo

boiling = (+q or -q) (endo or exo)

least

solids = (most, medium, least) motion

medium

liquids = (most, medium, least) motion

most

gases = (most, medium, least) motion

heat curves

shows temperatures at which a substance changes temperature (change in kinetic energy) OR changes phase (change in potential energy)

calorimetry

precise measurement of the heat flow into or out of a system for chemical/physical processes

enthalpy

when pressure is constant, q = ∆H

equilibrium temperature

-T final is the same for object 1 and object 2

-mC∆T (metal) = +mC∆T (water)

-mC∆T (metal/water) = +mC∆T (metal/water)