Lecutre 4: Phase Changes and Energy Lecture Flashcards

Vocabulary flashcards covering kinetic and potential energy, temperature scales, thermodynamic processes, and heat capacity calculations based on Chem 22 lecture notes.

Kinetic Energy

Energy associated with motion.

Potential Energy

Energy associated with positioning and/or composition, such as the attraction between particles.

Temperature

A measure of the average kinetic energy or thermal (heat) energy due to the random movement of particles.

Kelvin Scale conversion

$$K = \text{°C} + 273.15$$

Celsius Scale conversion

$$\text{°C} = \frac{\text{°F} - 32}{1.8}$$

Absolute Zero

The temperature at which random motion of atoms is theoretically zero, defined as $0\,K$ or $-273.15\,\text{°C}$.

Joule (J)

The SI unit of energy, defined as $kg \cdot m^2/s^2$.

calorie (cal)

The amount of energy needed to raise the temperature of $1\,g$ of water by $1\,\text{°C}$.

Food calorie (Cal)

Equivalent to $1\,kcal$ or a kilocalorie.

Sign Convention: (+)

Indicates the system gains energy.

Sign Convention: (–)

Indicates the system loses energy.

Exothermic process

A change that involves a release of energy as heat, where the system energy drops ($q < 0$).

Endothermic process

A change that involves absorbing energy as heat, where the system energy is gained ($q > 0$).

Intermolecular force

The attraction between particles, categorized as a type of potential energy.

Conservation of Energy

Energy cannot be created or destroyed, but can be transferred from one object to another ($E = K.E. + P.E.$).

Specific Heat capacity (c)

A measure of how much energy is necessary to raise the temperature of a substance, expressed in units like $J/g \cdot \text{°C}$.

Specific Heat capacity of water ($c_{water}$)

$$4.184\,J/g \cdot \text{°C}$$

Heat energy formula

$q = m \times c \times \Delta T$, where $m$ is mass, $c$ is specific heat capacity, and $\Delta T$ is the change in temperature ($T_f - T_i$).