Exam 1 Flashcards
What flows from
Hot to cold
Thermal equilibrium is reached
Over time reguardless of material ( any material will cool down or heat up to reach equilibrium
Energy
Capacity to do work
Work (w)
Force acting over a distance
Heat (q)
Flow of energy caused by a temperature difference
First law of thermodynamics
Energy can neither be created or destroyed
System
Whatever is actually undergoing change ( reaction) ex: chemicals doing a reaction
Surroundings
Everything around the reaction, beaker, water, air ect
Internal energy
Sum of all the kinetic energy and potential energy
State function
Property whose value is independent of pathway
If energy is gained
It’s positive internal energy (>E)
If the energy is released
It’s a negative > that’s a delta E
When the system gains thermal energy it’s is
Positive sign
When a system loses thermal energy it’s (q or heat)
Negative
Work(w) when work is done ON the system it’s
Positive
(W) when work is done BY the system it’s
Negative
Delta E( change in internal energy) energy flows INTO the system is
Positive
(E) energy flows out the system it’s
Negative
Work occurs when a______is caused by a _______ change against an external ________
1.Force
2.volume
3.pressure
Calorimetry
The process of measuring the amount of heat released or absorbed during a chemical reaction
Coffee cup calorimetry
Calculating the q (heat) based on changes in temperature at constant pressure
Bomb calorimetry
calculating the delta E of a system at constant volume
Heat capacity (c)
Systems ability to absorb thermal energy without undergoing a large change in system
Specific heat (c or cs)
Amount of heat required to raise a temperature of 1g of a substance by 1 degree C
Measuring a delta H of a reaction (enthalpy)
Measure of heat exchange at constant temperature
Endothermic
Heat absorbed +🔼H
Exothermic
Heat released (- 🔼H)
Heat of reaction absorbed or released depends on the _______ of reactants
Amount
Hess’s law (rule 1)
If equation is multiplied by a factor then 🔼Hrxn is multiplied by the same factor
Hess law rule 2
If the chemical equation is reversed the sign changes
Hess law 3
Add up the series of steps and the sum will be the 🔼 Hrxn for the overall equation
Spontaneous process
One that occurs without intervention ( ex rust)
Non spontaneous process
Not impossible but needs extra energy
Entropy
The amount of chaos randomness or disorder in a sample
Favorable +🔼S
More randomized sample
Unfavorable
-🔼S less randomized sample
For a exothermic process (enthalpy) a negative
No energy is required
For entropy the more random and positive value is
Easier to process energetically
Second law of thermodynamics: For any ________ process the entropy of the universe ________
- Spontaneous
- Increases
When the temperature is high
Impact on entropy is small
When temperature is low impact of entropy is
Significant
At higher temperature water becomes
Non spontaneous
Exothermic processes
Increase 🔼S surr
Endothermic processes does what to surrounding
Decrease 🔼S surr
If 🔼G is - the reaction is
Spontaneous
If 🔼G is + the reaction is
Nonspontaneous
Sign for Esys
Negative
Sign for Esurr
Positive
What role does a catalyst play in in thermodynamics
Catalyst don’t do anything in thermo it’s only in kinetics
Can a reaction be endothermic and spontaneous
Yes because the entropy can take over
Increase reactant concentration shifts it to the
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