Chapters 10-12 (Exam 3) Flashcards
(16 cards)
Exothermic vs Endothermic
Exothermic process is thermal energy FROM the system TO the surroundings
Endothermic is thermal energy absorbed by the system from its surroundings
calorie to joules fomula
1 calorie = 4.184 J 1 Calorie (kilocalorie) = 4184 J
open system vs closed system vs isolated system
Open- can exchange mass and energy with its surroundings; open water bottle
Closed- can exchange energy with its surroundings but not mass; closed water bottle
Isolated- does not exchange energy or mass with its surroundings; insulated closed water bottle
What are the state functions and what does it mean
Energy, pressure, volume, and temp. State functions properties that are determined by the state of the system, regardless of how that condition was achieved
What is the formula for the first law of thermodynamics
U=Uf-Ui
What is the formula to determine energy from work and heat
U = q + w
U is energy
q is heat (positive if absorbed)
w is work (positive if surroundings did the work)
work formula for pressure-volume
w= -P x /V
P is pressure
/V is change in volume
what is energy when there is a constant volume
q=/U
q is heat
U is change in energy
Enthalpy formulas
H = U + PV /H = /U + /(PV)
/H = H(products) - H(reactants)
if pressure is constant,
/H = /U + P /U
simplify
/H = q (when pressure is constant)
q is heat
p is pressure
v is volume
U is energy
How to find enthalpy in thermochemical equations
divide the total /H by the molar mass of the substance then divide by the coefficient
what is the formula for specific heat and work
q = s m /T
/T is change in temp
s is specific heat
m is mass
q is work
what is the equations for work and heat capacity
q = C /T
q is work
C is heat capacity
/T is change in temp
What are the constant volume calorimetry formulas
q(cal) = C x /T q(rxn) = -C x /T f q is work C is heat capacity /T is change in temp
What are the units for C
kJ/degC
How to do Hess law
you write the balanced equation and the /H and you add them together, canceling out like elements on opposite sides of the equation arrow.
Enthalpy of a reaction in the gas phase formula
/H = sum of the average bond enthalpy of the reactants - sum of the average bond enthalpy of the products
= total energy input (to break bonds) - total energy released (by bond formation)
