Types of Reactions in Chemistry: Physical, Chemical, and Nuclear

What are the three different types of reactions?

Physical Reactions, Chemical Reactions, Nuclear Reactions.

What characterizes a physical reaction?

Changing from one phase of matter to another without changing the compound's composition.

Give an example of a physical reaction.

Melting of ice, boiling of water, or dissolving salt in water.

What characterizes a chemical reaction?

The making and breaking of chemical bonds, resulting in compounds changing their elemental composition.

Provide an example of a chemical reaction.

Burning of fossil fuels, rusting of metals, or food metabolism.

What is a nuclear reaction?

Changing from one element to another, such as in the fusion of hydrogen atoms into helium.

What is the significance of the arrow in a chemical reaction?

It indicates the change from reactants to products.

What are the two types of energy changes associated with reactions?

Exothermic (produces energy) and Endothermic (requires energy).

What happens during melting in terms of energy?

It is an endothermic process where a solid changes to a liquid.

What is the process of freezing?

It is an exothermic process where a liquid changes to a solid.

What is sublimation?

The phase change from solid to gas, which is an endothermic process.

Define deposition in terms of phase change.

The phase change from gas to solid, which is exothermic.

What is condensation?

The phase change from gas to liquid, which is exothermic.

What is the Law of Conservation of Mass?

In chemical reactions, mass cannot be created or destroyed; the number of atoms must be the same on both sides of the reaction.

What is a stoichiometric coefficient?

A number placed in front of a molecule in a chemical equation to indicate the number of molecules involved.

How do you balance a chemical reaction?

By changing the stoichiometric coefficients to ensure the same number of atoms for each element on both sides.

What is an example of a combustion reaction?

CH4 + 2 O2 → CO2 + 2 H2O.

What is the result of combustion of organic molecules?

They react with oxygen to form carbon dioxide (CO2) and water (H2O), releasing heat.

What is the energy change during a chemical reaction where bonds are broken?

It requires kinetic energy to break high-energy bonds, making it endothermic.

What occurs when new bonds are formed in a chemical reaction?

Lower energy bonds are formed, releasing kinetic energy, making it exothermic.

What is the difference between exothermic and endothermic reactions?

Exothermic reactions release energy, while endothermic reactions require energy.

What is the significance of balancing chemical equations?

To ensure that the same number of each type of atom is present on both sides of the equation.

What is the result of an unbalanced reaction?

It indicates that mass is not conserved, violating the Law of Conservation of Mass.

What is the role of energy in phase changes?

All phase changes involve a corresponding change in energy level.

What happens to the energy during the evaporation of water?

It is an endothermic process that requires energy.

What is the relationship between reactants and products in a reaction?

Reactants are transformed into products, often with a change in energy.

What is an example of a reaction that involves allotropy?

The transformation between different structural forms of an element, like carbon as graphite and diamond.