EXAM 1

Question 1

What is energy?

Answer 1

Energy is the capacity to do work or transfer heat

Question 2

What are the two types of energy?

Answer 2

• Potential
• Kinetic

Question 3

Define potential energy.

Answer 3

Potential energy refers to the energy of position or chemical composition

Question 4

Define kinetic energy.

Answer 4

Kinetic energy refers to energy of motion

Question 5

What does the equation Energy = q + w represent?

Answer 5

It represents the total energy as the sum of thermal energy (q) and work (w), both path-dependent

Question 6

What is q in thermodynamics?

Answer 6

q is thermal energy: average kinetic energy of molecules due to their motion measured by temperature

Question 7

What is the effect of q on temperature?

Answer 7

Increases the temperature of an object

Question 8

What are the different types of kinetic motions?

Answer 8

• Translational
• Rotational
• Vibrational

Question 9

What is work in the context of thermodynamics?

Answer 9

Work is the energy required to move an object with mass in a specific direction

Question 10

What happens when a bond is formed?

Answer 10

Forming a bond releases energy

Question 11

What happens when a bond is broken?

Answer 11

Breaking a bond requires energy

Question 12

What do the Laws of Thermodynamics state about the universe?

Answer 12

The energy in the universe remains constant; it is conserved, and is only transformed and/or transferred

Question 13

Define ‘System’ in thermodynamics.

Answer 13

System refers to the area of study, such as a reaction or dissolution

Question 14

Define ‘Surroundings’ in thermodynamics.

Answer 14

Surroundings refer to everything else in the universe except the system

Question 15

What is the principle of heat exchange in thermodynamics?

Answer 15

Heat gained = Heat lost

Question 16

What is internal energy?

Answer 16

Internal Energy is the total kinetic and potential energy in a system

Question 17

Is internal energy a state function?

Answer 17

Yes, internal energy is a state function and path-independent

Question 18

What is the formula for calculating internal energy?

Answer 18

Internal Energy = Final - Initial

Question 19

What do spontaneous processes result in?

Answer 19

An increase in the entropy of the universe, leading to more disorder

Question 20

What is entropy (S)?

Answer 20

Entropy is a measure of the dispersion of energy in a system at a particular temperature

Question 21

What is the equation relating entropy change to enthalpy change and temperature?

Answer 21

ΔS = ΔH/T

Question 22

Can a process be spontaneous at one temperature but not at another?

Answer 22

Yes, a process may be spontaneous at one temperature and not at another

Question 23

What is the equation for the change in entropy of the universe?

Answer 23

ΔSuniv = ΔSsys + ΔSsurr

Question 24

List factors that increase entropy.

Answer 24

• Increase in volume
• Increase in temperature
• Greater molecular complexity
• Greater molar mass
• Moles of reactants < moles of products
• More linear and rigid structures
• Phase change from solid to liquid/aqueous
• Increase in the number of moles (same phase)
• Phase change from liquid to gas

Question 25

What is the standard entropy for one mole of a pure crystalline solid at 0 K?

Answer 25

0

Question 26

What happens to entropy at higher temperatures?

Answer 26

Entropy is higher than 0 due to random motion of molecules

Question 27

What is the formula for enthalpy (H)?

Answer 27

H = E + PV

Question 28

What does ΔH represent in a reaction?

Answer 28

ΔH represents the heat transferred by a reaction or phase change at constant pressure

Question 29

How is energy change estimated in calorimetry?

Answer 29

Using the equation q = mcΔT

Question 30

What does mcΔT represent in calorimetry?

Answer 30

m = mass of substance or n = moles of substance; c = specific heat capacity; ΔT = Tf - Ti

Question 31

What is the relationship between temperature and phase change?

Answer 31

In a phase change, temperature is constant and both phases are in equilibrium

Question 32

What is Hess's Law?

Answer 32

If a reaction occurs in a series of steps, the enthalpy of reaction is the sum of the enthalpies at each step

Question 33

What is Gibbs's Free Energy (ΔG)?

Answer 33

ΔGsys = ΔHsys - TΔSsys

Question 34

What does ΔSuniv > 0 and ΔG < 0 indicate?

Answer 34

The process is spontaneous

Question 35

What does ΔSuniv = 0 and ΔG = 0 indicate?

Answer 35

The process is reversible (in equilibrium)

Question 36

How does temperature affect spontaneity when ΔH and ΔS have the same sign?

Answer 36

Magnitude and temperature of the process must be considered to predict spontaneity

Question 37

When is a process spontaneous at high temperatures?

Answer 37

When both ΔH and ΔS are positive

Question 38

When is a process spontaneous at low temperatures?

Answer 38

When both ΔH and ΔS are negative

Question 39

Standard States

Answer 39

C --> C(s,graphite) Br2 --> Br2(l) I2 --> I2(s) Hg --> Hg(l) FONClH --> gases