Final Exam Flashcards
Atomic number
The number of protons in an atom
Mass number
Mass of all protons + neutrons in an atom
What property is the energy carried by photons most directly associated with?
Frequency
Definition of a heterogeneous mixture
A mixture with non-uniform composition
Definition of a homogeneous mixture
A mixture with uniform composition
Nano
10^9
Micro
10^6
Mega
10^-6
What is an orbital node?
An area around the nucleus where the probability of finding an electron is greater than zero
What is a net ionic equation?
An equation including only the molecules that are actively involved in a reaction, that are changed by the reaction. Excludes spectator ions
What is entropy a measure of?
How energy is distributed in a system. Units: J/K
How do you find velocity if given wavelength and frequency?
velocity = (wavelength)(frequency)
How do you calculate the energy of electrons in a hydrogen atom?
E = -(Rydberg energy)/(n^2)
Rydberg energy is given on the sheet, n is the principle electron orbital quantum number (1 for hydrogen)
How do you calculate the change in energy caused by an electron transitioning across different electron shells/levels (Bohr model rings)?
delta E = -(Rydberg energy)(Z/n - Z/n)
This one is given on the sheet
Z = atomic number
n = principle electron orbital quantum number
How do you calculate the specific heat of something if given the mass and temperature change from a calorimetric experiment?
qA = -qB
(C)(m)(Tf - Ti) = - (C)(m)(Tf - Ti)
The left and right sides of the equation describe two different substances, the ones the heat was transferred to in the experiment. Each has a different C (specific heat capacity)
m is mass, T is temp
How do you calculate the work done on a system?
w = - (P)(delta V)
w = delta E - delta H
How do you calculate partial pressures for compounds in a solution?
Pvap = ∑ (mole fraction)(partial pressure)
Remember that mole fraction is the moles of solute over total moles in solution
What do weaker IMFs mean for vapor pressure and boiling point?
Higher vapor pressure, lower boiling point
What do stronger IMFs mean for vapor pressure and boiling point?
Lower vapor pressure, higher boiling point
Which has more potential energy, the heat of fusion or the heat of vaporization?
Heat of vaporization
What predicts spontenaity?
Delta G, NOT delta S!
What happens to entropy when:
Temp decreases
Volume decreases
Entropy decreases
What happens to entropy when:
Temp decreases
Volume remains constant
Entropy decreases
What happens to entropy when:
Temp decreases
Volume increases
Need more info
What happens to entropy when:
Temp remains constant
Volume decreases
Entropy decreases
What happens to entropy when:
Temp remains constant
Volume remains constant
Entropy remains constant
What happens to entropy when:
Temp remains constant
Volume increases
Entropy increases
What happens to entropy when:
Temp increases
Volume decreases
Need more info
What happens to entropy when:
Temp increases
Volume remains constant
Entropy increases
What happens to entropy when:
Temp increases
Volume increases
Entropy increases
When is a rxn spontaneous?
When delta G is negative
When is a rxn NOT spontaneous?
When delta G is positive
In exothermic rxns, what happens to delta S?
It’s positive
In endothermic rxns, what happens to delta S?
It’s negative
How do you calculate the heat needed to make a substance undergo a phase change, given a specific starting temp?
(mass of substance)(specific heat capacity)(needed delta T)
+
(moles of substance)(molar heat of phase change)
Solve for these two and add them together. The first one is the heat needed to raise the substance’s temp to the start point of the phase change. The second one is the heat needed to actually complete the phase change.
Which phase changes increase entropy?
s to l, l to g, s to g
fusion, boiling, sublimation
Which phase changes decrease entropy?
g to l, l to s, g to s
condensation, crystallization, deposition
Think about the clausius-clapeyron equation. What happens to vapor pressure as temp increases?
Vapor pressure also increases
Think about the clausius-clapeyron equation. What do smaller delta Hvaps do to the graph of:
x = temp, y = vapor pressure
Steeper exponential increase
(half parabola, cut off at midpoint 0,0)
They shift the vertical “asymptote” closer to the y-axis
Think about the clausius-clapeyron equation. What do larger delta Hvaps do to the graph of:
x = temp, y = vapor pressure
Slower exponential increase
(half parabola, cut off at midpoint 0,0)
They shift the vertical “asymptote” farther away from the y-axis
How do you calculate mass percent of a concentration/solution?
(mass of solute)/(mass of solution) x100
What does it mean if you are given a substance’s solubility (for example in g/L) in the setup to a problem?
It means you already know the maximum possible concentration of the substance in the solution.
