Thermodynamics and Enthalpy

Flashcards about Thermodynamics and Enthalpy

Energy

The capacity to move things. If A has more energy than B, then A can cause more motion than B.

First Law of Thermodynamics

The energy of an isolated system is constant. ΔE (system) + ΔE (surroundings) = 0. Energy isn't created or destroyed but transferred as heat and/or work.

Exothermic

A system that releases heat (q < 0).

Endothermic

A system that absorbs heat (q > 0).

Work

When the system does work (-w), t.in > t.ii against a force. W = -P * ΔV

State Function

A property whose value does not depend on the path taken to achieve a specific value.Examples include: Potential energy and enthalpy (H).

Enthalpy (H)

A thermodynamic property defined as H = E + pV, where ΔH = q when the pressure is constant.

Calorimetry

The process of measuring heat transfer using an insulated vessel (calorimeter) and water.

Enthalpy of Formation

The enthalpy change for the formation of 1 mole of a substance in its standard state from its constituent elements in their standard states.

Hess's Law

The enthalpy change for a reaction is the same whether it occurs in one step or in a series of steps.

Formation Reaction

The reaction forming a product from its elements in their natural state.

ΔHr

Heat released by the reaction.

ΔH

Change in enthalpy; In a chemical reaction, when the pressure is constant, DH is equal to the amount of heat that was transferred to or from the surroundings.