Chemistry - Chapter 5

1 cal = ?J

4.184

System

The system includes the molecules we want to study

Surroundings

Everything else surrounding a system

First Law of Thermodynamics

Total energy of the universe is constant. If system loses energy, it must be gained by the surroundings and vice versa.

E°=?

Standard conditon

What happens to T of surrounding v system when energy is lost to surroundings

T of surrounding increases and T of the system decreases.

What happens to T of surrounding v system when energy is gained from surroundings

T of surrounding decreases and T of the system increases.

Exothermic

-Loss of energy

-Energy added to system

-Emitted energy

-Feels hot

-ΔH is negative

Endothermic

-Gain of energy

-Energy produced

-Absorbed energy

-Feels cold

-ΔH is positive

Energy + ΔH on the RIGHT side of equation is which type of process?

Exothermic reaction

Energy + ΔH on the LEFT side of equation is which type of process?

Endothermic reaction

Energy moves from ___ to ___

high to low

ΔH= ?

H products - H reactants

Extensive

Increase with amount

Enthalpy

the sum of a system's internal energy + product of its P and V

Enthalpy of fusion

Energy of phase change

Lattice energy

Energy to break ionic bond

Does the path of the reaction matter?

No, only the start and end are important

ΔH°f means…

Standard enthalpy of formation

ΔH°f of elements in their standard state equals?

0

ΔH°f O3 =

142.2 KJ/mol

Hess’s Law

If a reaction is carried out in a series of steps, ΔH for the overall reaction will be equal to the sum of the enthalpy changes for the individual steps.

What does enthalpy of solution depend on?

Enthalpy of hydration and enthalpy of lattice energy.

Colligative proprties

Higher the i value the higher the Bp and the lower the Fp.

Lattice energy

Amount of energy needed to break an ionic bond.

Transcriptions (ctriated complex)

When the bonds start to break in the reactants

When two bonds come together, is that endo or exo?

Exo

When a bond breaks is it endo or exo?

Endo

Heat Capacity

Energy needed to increase the temperature of a substance by one degree

Specific Heat (Specific Heat Capacity)

Energy needed to increase temperature of 1 gram substance

Molar Heat

Energy needed to increase temperature of 1 mole of substance

Extensive

Depends on the amount of substance

Intensive

Does not depend on the amount of the substance