L1 - GENCHEM (2nd Sem)

Thermodynamics

Study of energy and its transformations (or Interconversions)

Thermochemistry

A branch of thermodynamics that deals with the relationships between chemical reactions and energy changes involving heat

Kinetic Energy

The energy associated with an object by virtue of its motion

Potential Energy

The energy available by virtue of an object’s position

Mechanical Energy

The energy at work

Solar Energy

The energy from the sun that is converted into thermal or electrical energy

Electrical Energy

The energy of the mobile electrons that produce electricity

Thermal Energy

The energy associated with the random motion of atoms and moecules

Chemical Energy

• It is stored within the structural units of chemical substances.

• When substances participate in chemical reactions chemical energy is released, stored, or converted to other forms of energy.

• Energy is released when bonds form and, energy is consumed when chemical bonds are broken

Chemistry

it is the study of matter, and energy affects matter

Energy

the capacity to do work or to produce heat

Work

is a force acting over a distance
energy = ___ = force x distance

Heat

is the energy used to raise the temperature of an object

work

Chemistry defines ___ as directed energy change resulting from a process.

Energy

can be exchanged between objects through contact/collisions

Heat and work

represent two distinct ways through which an object can exchange energy with other object

Heat

is the transfer of thermal energy between two bodies that are at different temperatures. Energy generally flows from a hotter object to a cooler one until thermal equilibrium is reached.

Temperature

is a measure of the thermal energy

System

The specific part of the universe under study in which a change occurs

Surroundings

The rest of the universe outside the system

Open, Close, Isolated

three types of system

Open system

Can exchange mass and energy, usually in the form of heat with its surroundings

Closed system

Allows the transfer of energy (heat) but not mass

Isolated system

It does not allow the transfer of either mass or energy

Endothermic, exothermic

Types of heat reaction

Endothermic Process

Any process which heat has to be supplied to the system by the surroundings (q is positive)

Example: The heat from the surrounding is absorbed by the ice cube

Exothermic Process

Any process that gives off heat- transfers thermal energy to the surroundings. (q is negative)

Example: The heat generated by the combustion process is transferred from the system to its surroundings.

Zeroeth Law

Temperature ;
Two systems in equilibrium with a third system are in thermal equilibrium with each other.

First Law

Conservation of Energy ;
Energy can change forms, but is neither created nor destroyed.

Second Law

Entropy of an isolated system always increases.

Third Law

Entropy of a system approaches a constant as temperature approaches absolute zero.

Law of Conservation of Energy

What is the First Law of Thermodynamics

First Law of Thermodynamics: Law of Conservation of Energy

• When energy is exchanged between objects or transformed into another form, all the energy is still there.

• The total amount of energy in the universe before the change has to be equal to the total amount of energy in the universe after.

Internal Energy

• is the total amount of kinetic and potential energy a system possesses.

• The change in the ____ of a system depends only on the amount of energy in the system at the beginning and end.

State function

are properties that are determined by the state of the system, regardless of how that condition was achieved.

Heat

• one of the component of internal energy

• ____ is not a state function

Heat Capacity

the amount of heat needed to increase the temperature of an object by exactly 1°C

Dependent on 2 things:

• Mass of the object

• Chemical Composition

Specific heat

The amount of heat it takes to raise the temperature of 1 g of the substance by 1°C

Written as J / (g x °C)

Specific Heat

is an intensive property whereas heat capacity is an extensive property.

Calorimetry

It is the process of measuring the amount of heat released or absorbed during a chemical reaction.

Energy

exchanged between the system and the surrounding through work and heat