Chemistry 112 Exam 1

Terms in this set (33)

Bomb calorimeter equation
measures the change in energy for combustion reactions
qcal = Ccal deltaT
qcal = -qrxn
deltaE = qrxn
Styrofoam cup calorimeter equation
deltaH(rxn) = qrxn = -qh20
qh20 = mh20 x Cs(h20) x deltaT
Heat of Absorption
q = C x deltaT (CAT equation)
Heat absorption equation for calorimetry = qh20 = C(cal)deltaT
Forming a bond
exo
Breaking a bond
endo
Standard molar enthalpy of formation definition
the enthalpy of the formation of 1 mole of a substance at standard pressure and at a specified temperature formed from the most stable forms of the elements that crystalize it.
State property
only dependent on initial and final state and not on the path taken btwn initial and final state
First law of thermodynamics
energy is neither created nor destroyed
total energy of universe is constant
Heat
the flow of energy caused by a difference of temperature (btwn system and surroundings)
Hess's Law
If two or more equations are added together to form a new equation then the enthalpy's of the new equation is equal to the sum of the enthalpies of the initial equations.
Energy
the capacity to do work
work
the result of force acting through a distance
Kinetic energy
example: thermal (vibrational, rotational, translational)
equation: KE = 1/2 mass x (volume)^2
Potential energy
example: chemical (nuclear, gravitational, electrical)
standard enthalpy of formation equation
deltaHrxn = sum of deltaHprod - sum of deltaHreact
chemical energy
energy associated with the relative position of electrons and nuclei in atoms or molecules
thermal energy
energy associated with temp. of an object
enthalpy of combustion
equals enthalpy of reaction
zeroth law of thermodynamics a.k.a. the law of thermometry
when two objects are in contact with each other they will exchange energy for a time and they will stop changing. we then say they have the same temp.
SI unit of energy
Joules
Joules converstions
1kJ = 1000J
1J = Nm
1 cal = 4.184J
1Cal = 1kcal = 1000cal
thermodynamics
study of energy and its interconversions
internal energy
the sum of KE and PE of all the particles that compose the system
Work equations
deltaE = w + q
deltaEsys = - deltaEsurr
work done on system
+
work done by system
-
heat gained
+
heat lost/evolved
-
Specific heat capacity (Cs)
q = m x Cs x deltaT
q1 + q2 +q3 = ?
0
Use when given multiple q values to solve for T final
Formula for pressure
P = F/A
Enthalpy and energy equation
H = E + PV
Constant volume vs. constant pressure
Constant P = E released as heat and work
Constant V = E released only as heat
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