SAT CHEM Flashcards
Units of Pressure
760 torr = 760mmHg = 1 atm
Units of Energy
calories (cal) and joules (J)
Breaking bonds _______ energy
Requires
Forming bonds _______ energy
Releases
Specific heat def
The amount of heat to raise the temperature of 1g of a substance by 1 degree Celsuis
q=
m (mass )* c (specific heat) * delta T (change in temperature)
Use Celsius
Diatomic Elements
Oh I Have Nice Closets For Brooms
O I H N Cl F BR
Avogadro’s Number (Mole)
6.02*10^23
1 amu
1/12 mass of C-12 a.k.a 1g
convert from mass composition to the empirical formula
- convert percent into 100g: 50% = 50g
- Convert to Moles
- Divide by smallest mole and round to nearest integer to get ratio
Entropy
Measure of disorder
The higher the entropy and the lower the energy the more stable it is
Symbolized by delta S
Enthalpy
Direct relationship between enthalpy and energy
Universe like low enthalpy and high entropy
Symbolized by H
When delta H is negative it is exothermic and enthalpy decreases therefore occurs more often
When delta H is positive it is endothermic and enthalpy increases therefore doesn’t occur as often
Heat of Formation
Symbolized by delta H subscript f
If negative heat is released and vice versa when it is positive
Elements have a heat of formation of 0
Hess’s Law
delta H will be equal to the sum of the enthalpy changes in individual steps whena reaction occurs in more than one step
Gibbs’ Free Energy
delta G = delta H - T*delta S
Temperature is in Kelvin
When delta G is negative occurs spontaneous in forward reaction
When delta G is positive occurs spontaneous in reverse reaction
When delta G is 0 occurs reached equilibrium
