# Chapter 10 Thermodynamics

## 20 terms

### heat

the energy transferred between objects that are at different temperatures; energy is always transferred from higher-temperature to lower temperature objects until thermal equilibrium is reached.

### enthalpy

the sum of the internal energy of a system plus the product of the system's volume multiplied by the pressure that the system exerts on its surroundings.

### temperature

the measure of how hot or cold something is; specifically a measure of the average kinetic energy of the particles in an object.

### calorimetry

the measurement of heat-related constants such as specific heat or latent heat.

### specific heat

the quantity of heat required to raise a unit mass of homogeneous material 1°K or 1°C in a specified way given constant pressure or volume. the most common unit is J/g x C°

### molar heat capacity

the energy required to raise the temperature of one mole of a substance by one degree Celsius

### 25 Joule Rule

states that the temperature of one mol of any solid metal or solid ionic compound is raised 1 °K when the metal absorbs 25 J of heat.

Uses an insulating vessel; means "not allowing energy to pass through" thus no energy can enter or leave this vessel. As a result, the reaction mixture increases in temperature if the reaction is exothermic or decreases in temperature if the reaction is endothermic. It is used for reactions that are not ignited, such as for reaction in aqueous solutions.

### thermodynamics

a branch of science concerned with the energy changes that accompany chemical and physical changes.

### thermochemistry

the study of the transfers of energy as heat that accompany chemical reaction and physical changes.

### Hess's Law

the overall enthalpy change in a reaction is equal to the sum of enthalpy changes for the individual steps in the process.

### heat of formation

the heat evolved or absorbed during the formation of one mole of a substance from its component elements

### heat of combustion

the energy released as heat by the complete combustion of one mole of a substance.

### entropy

the measure of the amount of disorder or randomness of a system.

### Gibb's free energy

third thermodynamic quantity; predicts if a reaction will be stable or not; the energy in a system that is available for work.

### spontaneous

a reaction that is thermodynamically favored and generally can sustain itself once the activation energy has been supplied.

### endothermic

describes a reaction that absorbs energy from the surroundings

### exothermic

describes a process in which a system releases heat into the environment.

### heat of reaction

the quantity of energy released or absorbed as heat during a chemical reaction.

### molar heat of formation

the energy released or absorbed as heat when one mole of a compound is formed by combination of its elements. Given using their standard states, room temperature and atmospheric pressure. (ΔH°f)