Energy changes in chemical and nuclear reactions

Thermochemistry

What describes the study of energy changes that accompany physical and chemical changes in matter

Fission

What describes the splitting of a larger atom into 2 or more smaller ones

Fusion

What describes the joining of 2 or more smaller atoms into a larger one

Energy

The ability to do work

Kinetic energy

the energy of an object due to its motion (translation, rotation, vibration)

Potential energy

the energy of a body or system due to its position or composition – found in chemical bonds (released when new bonds form)

Nuclear energy

(stored in the nucleus as energy needed to hold the nucleus together)

Thermal energy

total potential and kinetic energy of a substance

Heat

The transfer of thermal energy from a warm object to a cooler object

Temperature

the average kinetic energy of the particles in a sample, measured in °C or K

temperature

Energy flows between substances because of their difference in ___________

s

Quick note (press s to skip)

Laws of conservation of energy

• The total energy of the universe is constant

• Energy can neither be created nor destroyed

• Energy can be transferred from one substance to another

• Can be converted into various forms

chemical system

a set of reactants and products under study, usually represented by a chemical equation

Surroundings

all matter around the system that is capable of absorbing or releasing thermal energy

Surroundings

Any change in the system is accompanied by an equal and opposite change in the _____________.

Open system

A system where both matter and energy can move in and out (Example: Open mug)

Closed system

A system where energy can move in and out, but not matter (Example: Coffee cup with lid)

Isolated system

An ideal system, where neither energy or matter can move in or out (Example: insulated coffee cup with lid)

energy

The total ______ of a system is equal to the sum of the potential and kinetic energy of all species in the system

Kinetic energy

What kind of energy examples:

• moving electrons in atoms

• vibration, rotation and translation of atoms and molecules

Potential energy

What kind of energy examples:

• nuclear potential energy of protons and neutrons

• bond energy (stored energy)

• intermolecular forces

heat

When a reaction occurs, ____ is transferred between substances.

Exothermic

change involves releasing thermal energy as heat flows out of the system

Endothermic

change involves absorbing thermal energy as heat flows into the system

released

In exothermic reactions, does energy get released or absorbed?

negative

In exothermic reactions, is the q value positive or negative?

absorbed

In endothermic reactions, does energy get released or absorbed?

positive

In endothermic reactions, is the q value positive or negative?

Surroundings

In exothermic and endothermic reactions, it involves heat, systems, and ____________.