Chapter 7 - Energy and Chemical Processes

Energy

capacity to do work

Specific Heat

amount of energy needed to raise one gram of water up 1 degree celsius

Calorie

unit of measurement for energy

1000 calories = ?

1 kcal

1 Calorie = ?

1 kcal

1 calorie = ?

4.184 joules

formula for energy

E = m x c x Δt

Enthalpy

energy stores in a substance, unit of H

Enthalpy change

is the amount of heat content lost or gained during a chemical reaction at constant pressure.

exothermic rxn: energy is released

endothermic rxn: energy is gained

activation energy

added for bonds reaction to occur

activated complex

a high-energy, unstable intermediate state formed during a chemical reaction when bonds and reactants are broken, as well as new bonds are forming

What is the difference between activation energy and activated complex?

Activation energy is the minimum energy required to initiate a chemical reaction, while the activated complex is the, high-energy state that occurs as reactants transform into products.

endothermic reaction

A type of chemical reaction that absorbs energy from its surroundings, usually in the form of heat. Ex: melting of ice, evaporation, and photosynthesis

exothermic reaction

A type of chemical reaction that releases energy to its surroundings, often in the form of heat or light. Ex: combustion of fuels, lighting up a match

ΔHrxn = Σ(BDE)r - Σ(BDE)p

If the end product is a negative, is it a product or a reactant?

It is a product since it’s negative, indicating that energy is released during the reaction.

Endothermic - left side / reactant

Exothermic - right side / product

Bond Dissociation Energy

the energy required to break the bonds in one mole of a substance in the gas phase.

Stages of ice to steam

H2O (s, -4C) → H2O (s, 0C)

H2O (s , 0C) → H2O (l, 0C) fusion

H2O (l, 0C) → H2O (l, 100C)

H2O (l, 100C) → H2O (v, 100C) evaporation

H2O (v, 100C) → H2O (v, 110C)