Thermochemistry

Question 1

Thermochemistry

Answer 1

Study of the energy changes that take place during a chemical reaction.

Question 2

Isolated System

Answer 2

A system where neither matter nor energy can move in or out; used to study energy changes (ex: calorimeter).

Question 3

Calorimetry

Answer 3

Technological process of measuring energy changes in an isolated system.

Question 4

Calorimeter

Answer 4

Isolated system in which the chemical system (reactants and products) being studied is surrounded by a liquid (usually water)

Question 5

Thermal Energy (Q)

Answer 5

Total kinetic energy of the entities of a substance; Q=mcΔt

Question 6

Specific Heat Capacity

Answer 6

The amount of energy required to raised the temperature of a unit mass of a substance by one degree Celsius or Kelvin

Question 7

Enthalpy Change (ΔH or ΔrH)

Answer 7

The difference between the enthalpy of the products and the enthalpy of the reactants of a chemical reaction.

Question 8

Exothermic Reaction

Answer 8

Chemical reaction that releases energy to its surroundings; change results in a lower enthalpy of the chemical system (sign before numerical value is negative and energy is written with the products).

Question 9

Endothermic Reaction

Answer 9

Chemical reaction that absorbs the energy of its surroundings; change results in a higher enthalpy of the chemical system (sign before numerical value is positive and energy is written with reactants).

Question 10

Enthalpy of Reaction (ΔrHm)

Answer 10

Energy change for a whole chemical system per mole of a specified chemical undergoing change in the system.

Question 11

Standard Molar Enthalpy of Reaction

Answer 11

The molar enthalpy of reaction determined when the initial and final conditions of the chemical system are standard conditions.

Question 12

Reference Energy State

Answer 12

A reference point at which the potential energy of elements in their most stable form at SATP is defined at zero.

Question 13

Standard Molar Enthalpy of Formation

Answer 13

The enthalpy change calculated from measurements of a formation reaction under standard conditions.

Question 14

Thermal Stability

Answer 14

The tendency of a compound to resist decomposition when heated (characterized by the standard molar enthalpy- the more negative the enthalpy, the more stable the compound).

Question 15

Catalysis

Answer 15

Study of the properties and development of catalysts and their effects on rates of reaction.

Question 16

Catalysts

Answer 16

Substances that increase the rate of chemical reactions without being consumed themselves in the overall process.

Question 17

Enzymes

Answer 17

Compounds, usually proteins, that acts as catalysts in living systems; often responsible for controlling a certain physiological reaction; biological catalysts.

Question 18

Intermediates

Answer 18

Chemical entities that form with varying degrees of stability at the end of a step in a reaction mechanism.

Question 19

Enthalpy

Answer 19

The total kinetic and potential energy within a system at constant pressure.

Question 20

Activation Energy (Ea^t)

Answer 20

An energy barrier that must be overcome for a chemical reaction to occur; the minimum energy that entities must reach before they can react.