Final Exam

Question 1

Atomic number

Answer 1

The number of protons in an atom

Question 2

Mass number

Answer 2

Mass of all protons + neutrons in an atom

Question 3

What property is the energy carried by photons most directly associated with?

Answer 3

Frequency

Question 4

Definition of a heterogeneous mixture

Answer 4

A mixture with non-uniform composition

Question 5

Definition of a homogeneous mixture

Answer 5

A mixture with uniform composition

Question 6

Nano

Answer 6

10^9

Question 7

Micro

Answer 7

10^6

Question 8

Mega

Answer 8

10^-6

Question 9

What is an orbital node?

Answer 9

An area around the nucleus where the probability of finding an electron is greater than zero

Question 10

What is a net ionic equation?

Answer 10

An equation including only the molecules that are actively involved in a reaction, that are changed by the reaction. Excludes spectator ions

Question 11

What is entropy a measure of?

Answer 11

How energy is distributed in a system. Units: J/K

Question 12

How do you find velocity if given wavelength and frequency?

Answer 12

velocity = (wavelength)(frequency)

Question 13

How do you calculate the energy of electrons in a hydrogen atom?

Answer 13

E = -(Rydberg energy)/(n^2)

Rydberg energy is given on the sheet, n is the principle electron orbital quantum number (1 for hydrogen)

Question 14

How do you calculate the change in energy caused by an electron transitioning across different electron shells/levels (Bohr model rings)?

Answer 14

delta E = -(Rydberg energy)(Z/n - Z/n)

This one is given on the sheet
Z = atomic number
n = principle electron orbital quantum number

Question 15

How do you calculate the specific heat of something if given the mass and temperature change from a calorimetric experiment?

Answer 15

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

Question 16

How do you calculate the work done on a system?

Answer 16

w = - (P)(delta V)

w = delta E - delta H

Question 17

How do you calculate partial pressures for compounds in a solution?

Answer 17

Pvap = ∑ (mole fraction)(partial pressure)

Remember that mole fraction is the moles of solute over total moles in solution

Question 18

What do weaker IMFs mean for vapor pressure and boiling point?

Answer 18

Higher vapor pressure, lower boiling point

Question 19

What do stronger IMFs mean for vapor pressure and boiling point?

Answer 19

Lower vapor pressure, higher boiling point

Question 20

Which has more potential energy, the heat of fusion or the heat of vaporization?

Answer 20

Heat of vaporization

Question 21

What predicts spontenaity?

Answer 21

Delta G, NOT delta S!

Question 22

What happens to entropy when:
Temp decreases
Volume decreases

Answer 22

Entropy decreases

Question 23

What happens to entropy when:
Temp decreases
Volume remains constant

Answer 23

Entropy decreases

Question 24

What happens to entropy when:
Temp decreases
Volume increases

Answer 24

Need more info

Question 25

What happens to entropy when: Temp remains constant Volume decreases

Answer 25

Entropy decreases

Question 26

What happens to entropy when: Temp remains constant Volume remains constant

Answer 26

Entropy remains constant

Question 27

What happens to entropy when: Temp remains constant Volume increases

Answer 27

Entropy increases

Question 28

What happens to entropy when: Temp increases Volume decreases

Answer 28

Need more info

Question 29

What happens to entropy when: Temp increases Volume remains constant

Answer 29

Entropy increases

Question 30

What happens to entropy when: Temp increases Volume increases

Answer 30

Entropy increases

Question 31

When is a rxn spontaneous?

Answer 31

When delta G is negative

Question 32

When is a rxn NOT spontaneous?

Answer 32

When delta G is positive

Question 33

In exothermic rxns, what happens to delta S?

Answer 33

It's positive

Question 34

In endothermic rxns, what happens to delta S?

Answer 34

It's negative

Question 35

How do you calculate the heat needed to make a substance undergo a phase change, given a specific starting temp?

Answer 35

(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.

Question 36

Which phase changes increase entropy?

Answer 36

s to l, l to g, s to g fusion, boiling, sublimation

Question 37

Which phase changes decrease entropy?

Answer 37

g to l, l to s, g to s condensation, crystallization, deposition

Question 38

Think about the clausius-clapeyron equation. What happens to vapor pressure as temp increases?

Answer 38

Vapor pressure also increases

Question 39

Think about the clausius-clapeyron equation. What do smaller delta Hvaps do to the graph of: x = temp, y = vapor pressure

Answer 39

Steeper exponential increase (half parabola, cut off at midpoint 0,0) They shift the vertical "asymptote" closer to the y-axis

Question 40

Think about the clausius-clapeyron equation. What do larger delta Hvaps do to the graph of: x = temp, y = vapor pressure

Answer 40

Slower exponential increase (half parabola, cut off at midpoint 0,0) They shift the vertical "asymptote" farther away from the y-axis

Question 41

How do you calculate mass percent of a concentration/solution?

Answer 41

(mass of solute)/(mass of solution) x100

Question 42

What does it mean if you are given a substance's solubility (for example in g/L) in the setup to a problem?

Answer 42

It means you already know the maximum possible concentration of the substance in the solution.