Thermochemistry and Gases Practice Exam Flashcards

Vocabulary terms and definitions based on the practice exam for thermochemistry and gas laws.

Energy

The capacity to do work.

Work

The result of a force acting through a distance.

Heat

The flow of energy caused by a temperature difference.

System with $q = +$ and $w = -$

A system that is gaining heat from the surroundings while doing work on the surroundings.

System with $q = -$ and $w = +$

A system where the surroundings do work on the system while the system loses heat to the surroundings.

First Law of Thermodynamics

The law of conservation of energy typically expressed as $\Delta E_{\text{system}} = -\Delta E_{\text{surroundings}}$.

Enthalpy ($\Delta H$) at constant pressure

Under constant pressure, the change in enthalpy is equal to the heat ($q$).

Endothermic reaction

A reaction with a positive $\Delta H$ that absorbs heat from the surroundings and feels cold to the touch.

State functions

Properties that are path-independent, meaning their value does not depend on the steps taken to achieve a state.

Path function

A property whose value is path-dependent and describes the steps taken to achieve a state, such as work ($w$).

Standard Enthalpy of Formation ($\Delta H^{\circ}_f$) conditions

The substance must be a simple substance in its most stable form under $1\,atm$ of pressure.

Barometer

An instrument used to measure atmospheric pressure.

Avogadro's hypothesis in identical flasks

Identical flasks containing different gases at standard temperature and pressure will contain the same number of molecules.

Kinetic Molecular Theory (Collisions)

A theory stating that the collisions of particles with one another are completely elastic.

Ideal Gas behavior

A gas behaves most ideally under conditions of low pressure and high temperature.

Pressure in a tire

Air leaves a tire when the valve is open because the pressure inside the tire is higher than the pressure outside.

$1\,atm$ to $mm\,Hg$ conversion

The conversion factor where $2.00\,atm$ is equal to $1520\,mm\,Hg$.

$1\,atm$ to $psi$ conversion

The conversion factor where $2.00\,atm$ is equal to $29.4\,psi$.