Chemical Reactions

Flashcards about Chemical Reactions.

What is thermodynamics?

The area of chemistry that describes how energy and heat are exchanged in chemical reactions.

What always appears on the left side of a chemical reaction?

Reactants

What means 'yields' in a chemical reaction?

An arrow connecting reactants and products

What type of reaction gives off heat?

Exothermic reaction

What type of reaction absorbs heat energy?

Endothermic reaction

What is the thermodynamic term for the exchange of heat energy in a chemical reaction?

Change in enthalpy

For an exothermic reaction, is the change in enthalpy a positive or negative number?

Negative

For an endothermic reaction, is the change in enthalpy a positive or negative number?

Positive

What is the measure of the change in randomness in a chemical system?

Change in entropy

What is free energy (G)?

The amount of energy present in molecules available to do work.

What does an exergonic reaction do?

Gives off energy

What does an endergonic reaction do?

Requires energy

What is required for reactions with a positive free energy value?

Energy input from their surroundings

What molecule transfers energy in living systems?

Adenosine triphosphate, ATP

What is activation energy?

The energy required for a reaction to begin, where reactants collide with enough energy and the correct orientation.

What is combustion?

When oxygen reacts with molecules producing carbon dioxide, water, and energy.

Which nutrient molecule contains the highest amount of energy per gram?

Fat (9 Calorie/gram)

What is reaction kinetics?

The study of the pace or rate of a chemical reaction.

What factors affect the rate of a reaction?

Factors affecting the rate of collision or the energy available to the reaction.

How does increasing temperature affect reaction rates?

It increases the kinetic energy of reacting molecules, causing more collisions and reactions.

How does the amount of reactant affect reaction rates?

Increasing the amount of reactants increases the rate of chemical reactions.

What effect does a catalyst have on activation energy?

It lowers the activation energy.

What is the definition of a catalyst?

Participates in a chemical reaction but remains unchanged and can be used again.

What are enzymes?

Biological catalysts that increase reaction rates.

What is the active site of an enzyme?

A site on an enzyme where reactants are immobilized and oriented correctly for a reaction to occur.

What type of reaction occurs when smaller molecules combine to create larger molecules?

Synthesis reactions

What type of reaction breaks apart larger molecules into smaller molecules?

Decomposition reactions

What is a reaction called when it can form products in either direction?

Reversible reaction

What is chemical equilibrium?

The point when both the forward and reverse reactions are occurring at the same rate.

What type of reaction is highly exothermic and considered irreversible?

Combustion

What are the products of a combustion reaction?

Carbon dioxide and water

What is oxidation?

Atoms that lose electrons during a chemical reaction.

What is reduction?

Atoms that gain electrons during a chemical reaction.

What happens to metal atoms during oxidation and reduction?

Metal atoms lose electrons, forming cations (get oxidized).

What happens to nonmetal atoms during oxidation and reduction?

Nonmetals gain electrons, forming anions (get reduced).

What is an organic molecule oxidized?

If it gains oxygen or loses hydrogen.

What is an organic molecule reduced?

If it gains hydrogen or loses oxygen.

What is a condensation reaction?

Water is produced as two organic molecules are joined.

What is a hydrolysis reaction?

Water is consumed as a reactant, and the reactant molecule is split into two smaller molecules.

What is a hydrogenation reaction?

Two hydrogen atoms are added, converting an alkene double bond to an alkane single bond.