Chemistry 1128 Test

_____ occur without an outside stimulus when reactants come into contact with each other.

Spontaneous reactions

study of heat energy changes related to chemical reactions

thermochemistry

transfer of heat

thermodynamics

_____ is the type of energy lost due to friction during energy conversion.

Heat

enthalpy change for the overall reaction is the same as the sum of enthalpy changes for all the steps in the reaction

Hess's Law

Free energy is the change in enthalpy minus the product of the ______ temperature and the entropy change.

Kelvin

A system that adjusts itself back o equilibrium after being upset has operated on the basis of ____ principle.

Le Chatelier's

The structure called the _____ complex contains the partial bonds that exist between the old bond formation and the new bond formation

activated

transitional structure that results from an effective collision and persists while old bonds re breaking and new bonds are forming

activated complex

energy required to transform reactants into an activated complex

activation energy

Increasing reactant concentration in a system in equilibrium will cause the system to shift _____ the production of the added substance.

away from

Chemical energy is stored in the chemical ____ of an object.

bonds

A substance that increases the rate of a chemical reaction, but is not consumed in the process, is called a ______.

catalyst

Calculate the enthalpy of formation of 168.3 g of potassium hydroxide (KOH). Hf of KOH = -425.9 kJ/mol

change grams to moles and multiply by Hf

Enthalpy can be measured only when it _____

changes

set of assumptions regarding molecular collisions and reactions

collision theory

Increasing reactant or product ____ in a system in equilibrium will cause the system to shift away from the production of added substances.

concentration

first law of thermodynamics

constant energy and matter

activation energy is large and enthalpy change is positive

endothermic reaction

must be applied to break chemical bonds and released when bonds are formed

energy

Reactants with low ___ tend to remain unreactive.

enthalpy

another name for heat of reaction

enthalpy of formation

According to the second law of thermodynamics, the _____ of the system and its surroundings always increases in a spontaneous irreversible process.

entropy

The second law of thermodynamics states that in a spontaneous irreversible process, the total _____ of the system and its surroundings always increases.

entropy

The two factors, enthalpy and _____, work together to provide the driving force behind chemical reactions.

entropy

disorder, or randomness, of a system

entropy

Changes in concentration or pressure and adding a catalyst do not affect the ____ constant.

equilibrium

Concentration changes of reactants or products have no effect on the ____ constant.

equilibrium

point of no further change

equilibrium

Word does not produce heat in a _____ environment.

frictionless

When ice absorbs heat and melts, its enthalpy ...

increases

An _________ slows down a chemical reaction.

inhibitor

An object at rest has some ____ energy because the particles within it are moving.

kinetic

energy of motion

kinetic energy

A negative enthalpy of formation means heat is ____ by the formation of a compound

lost

The law of ______ explains the mechanism of equilibrium and its effect on t he rate of chemical reactions.

mass action

A system is a sample of _____ and energy under observation.

matter

A compound with a high _____ enthalpy of formation is usually a stable compound.

negative

Chemical bonds are broken when two compounds react and _____ are formed.

new bonds

Combustion reactions usually proceed faster if placed in an _____ environment.

oxygen

An object loses _____ energy as it moves to a lower position.

potential

By the first law of thermodynamics, the mass of the reactants equals the mass of the ____ in a chemical reaction

products

step by step sequence of reactions by which an overall chemical change occurs

reaction mechanism

If a reaction at equilibrium favors the ___ reaction, the result is a higher concentration of reactants.

reverse

The change in ______ affects the equilibrium constant.

temperature

Calculate the change in free energy of the reaction of zinc with sulfur, which produces zinc sulfate at 210C

Change temperature to Kelvin and Hf - T x S