Chemistry Reactions Quiz

Chapter 3: Energy, Chemical Reactions, and Cellular Respiration

• This chapter covers energy, chemical reactions, and cellular respiration.
• Learning objectives include comparing and contrasting potential and kinetic energy, describing how these relate to thermodynamics, explaining major types of chemical reactions (synthesis, decomposition, oxidation-reduction), and classifying reactions (anabolic, catabolic, endergonic, exergonic, reversible, irreversible).
• All living organisms require energy for various functions like powering muscles, pumping blood, absorbing nutrients, exchanging respiratory gases, synthesizing new molecules, and establishing cellular ion concentrations.
• Glucose is broken down through metabolic pathways (cellular respiration) that form ATP, which is the energy currency of cells.

Energy and ATP

• ATP is a nucleotide composed of a nitrogenous base (adenine), a ribose sugar, and three phosphate groups.
• It is the central molecule for transferring chemical energy within cells.
• Covalent bonds between the last two phosphate groups in ATP store energy.
• ATP releases energy when these bonds are broken.
• ATP formation is an endergonic reaction, requiring energy input.
• ATP splitting (hydrolysis) is an exergonic reaction, releasing energy.
• Released energy is used for various cellular processes, like body movement.

Energy

• Energy is the capacity to do work.
• Two types of energy are potential energy (position or stored energy) and kinetic energy (motion).
• Both types can change from one to another.
• Potential energy must convert to kinetic energy before doing work.
• Potential energy is energy stored in a molecule's chemical bonds
• Chemical energy is used for movement, molecule synthesis, and establishing concentration gradients.
• Molecules that function in chemical energy storage include triglycerides, glucose, and ATP.
• Examples of kinetic energy include electrical (movement of ions), mechanical (muscle contraction), sound, radiant (visible light), and heat.

Chemical Energy

• Chemical energy is a form of potential energy stored in the chemical bonds of molecules.
• Chemical energy is released when bonds break, converting chemical energy to other forms.
• This energy is used in various ways: Movement, molecule synthesis, establishing concentration gradients.

Kinetic Energy

• Electrical energy is the movement of ions.
• Mechanical energy is the movement of muscles.
• Sound energy is sound waves causing vibration.
• Radiant energy is visible light.
• Radiant energy is electromagnetic waves.
• Heat is the movement of atoms, ions, and molecules.

Laws of Thermodynamics

• Thermodynamics is the study of energy transformations.
• The first law states that energy cannot be created or destroyed, but only transformed.
• The second law states that when energy is transformed, some energy is lost to heat, for instance, body movement during cold weather.

Chemical Reactions

• Chemical equations represent chemical reactions, showing reactants (starting materials) transforming into products (new substances).
• Chemical reactions involve breaking and forming chemical bonds.
• Reactants are the substances that exist before the reaction takes place and products are the substances that result after the reaction takes place
• Reactants and products are located on different sides of the arrow (left for reactants and right for products) in the equation.
• The number of atoms of each element on each side is always equal.

Classification of Chemical Reactions

• Chemical reactions are classified by changes in chemical structure, energy, and reversibility.
• Some types of chemical reactions include: synthesis, decomposition, exchange, and oxidation-reduction.
• Synthesis reactions combine small units to form large ones (anabolism).
• Decomposition reactions break down large units into small ones (catabolism).
• Exchange reactions swap or exchange components between molecules (e.g., ATP production in muscle tissue).
• Oxidation-reduction (redox) reactions involve the transfer of electrons from one molecule to another.

Oxidation-Reduction Reactions

• Oxidation-reduction (redox) reactions are electron exchange reactions.
• Oxidized molecules lose electrons; reduced molecules gain electrons.
• An example of a redox reaction is NAD+ to NADH.

Classification of Chemical Reactions: Energy

• Exergonic reactions involve a net release of energy, with products having less energy than reactants.
• Endergonic reactions require a net input of energy, where products have more energy than reactants.

Reversible and Irreversible Reactions

• Irreversible reactions proceed only in one direction and are characterized by the net loss of reactants and gain of products.
• Reversible reactions can proceed in both directions, and no net change in concentration of reactants or products occurs at equilibrium. An example is the carbonic acid reaction.

Carbonic Acid Reaction

• This is a reversible reaction.
• Carbon dioxide and water react to form carbonic acid, which is unstable and dissociates to form bicarbonate and hydrogen ions

Test your knowledge with this quiz on various types of chemical reactions and processes. Questions cover energy inputs, bond breaking, and the principles of oxidation and reduction. Perfect for chemistry students looking to reinforce their understanding.