Exam 2 Flashcards
Reacting molecules must collide w/ one another: collision theory… which molecules ?
Concentration and temperature
Calc. Molar mass from freezing point or boiling point
Step 1: find 🔺T
Step 2: molality using =🔺T/Kb
Step 3: moles of solute
Step 4: molar mass
Moles of solute:
m (lower case) x Kg of solvent
Molar mass: g/mol
= mass of solute/moles of solute
Collision theory: concentration
It is increases likelihood of collisions
Collision theory: temperature
At higher temps, reactant molecules have MORE KE, and collide more often w greater energy
K is dependent on what?
Temperature
Arrhenius equation linear:
ln(k): -Ea/(R)(T) + ln(A)
Arrhenius eq. Two data points:
ln(k1/k2)= -Ea/R (1/T1 - 1/T2)
Finding Ea from graph (y=mx+b)
Ea= -slope x R (8.314)
In collision theory, !!!orientation matters !!!
For reaction to occur and not just bounce off of each other
Collision theory: energy
Energy is used to stretch bend and break chemical bonds
Reactants must overcome ____ ____ barrier in order for reaction to occur
Minimum energy
The minimum energy required for reaction to occur is called …
Activation energy
Endo or exo thermic on graphs
(Above or below the line)
🔺H positive: endothermic
🔺H negative: exothermic
The lower the activation energy, the ___ the reaction
Faster
Catalyst:
Consumed in reaction, and produced later
(Present in beginning and end)
Intermediate:
Produced first in reaction, and consumed later (present only in between reactions)
