Notes, summaries, assignments, exams, and exercises for Chemistry for Baccalaureate

Chemical Kinetics and Reaction Rates

Factors Influencing Reaction Velocity

• Rate Equation: V = k · [A]^a · [B]^b
• Temperature: The Arrhenius Law: k = k₀ · e^{-E_a / (R · T)}
• Concentration and Pressure: P · V = n · R · T
  P = (n · R · T) / V → n / V = concentration
  P = [X] · R · T
• Standard State and Physical State:
  • Solid: Few collisions result in slow reactions. The level of division is key; more particles mean a greater impact surface.
  • Liquid: Average collision frequency results in average reaction speeds.
  • Gas: Many collisions result in faster reactions.
• Catalysts: Positive catalysts increase speed. Negative catalysts (inhibitors) slow it down. Catalysts do not change thermochemical quantities (ΔH, ΔG, ΔS...), the quantity of product, or

metallic bond: the bond strength between metal atoms, which owe their stability and properties of metallic lattices. Covalent bonding is the joining of two atoms q comprten one or more pairs of electrons. The salt bridge is the union resulting from the presence of electrostatic forces between positive and negative ions lead to the formation of a compound substituted ionic x a crystal lattice. The covalency of elmento is the number of covalent bonds can form q, which q depends on the number of unpaired electrons. Binding parameters: the binding energy of a diatomic molecule is the enthalpy q occurs when one mole dissociates of molecules in a gas of atoms in the same state. Bond length is the distance between the nuclei of 2 atoms linked by a...

What is Matter?

Matter is anything that occupies space and has mass. This includes land, water, air, and more. Essentially, if something exists physically, it is considered matter.

Theories of Matter

Historically, there were two main theories regarding the divisibility of matter:

• Matter is discontinuous: This theory proposed that there is a fundamental, indivisible unit of matter. This smallest unit was called an "atom."
• Matter is continuous: This theory suggested that matter could be infinitely divided into smaller and smaller parts.

It was eventually proven that matter is discontinuous, meaning atoms exist.

Thompson's Atomic Model

J.J. Thompson's model, often called the "plum pudding" model, depicted the atom as a sphere of positive charge with negatively...

Fundamental Chemical Processes

Reduction: Electron Gain in Chemistry

Reduction is an electrochemical process by which an atom or ion gains electrons, implying a decrease in its oxidation state. This process is the opposite of oxidation.

When an ion or atom undergoes reduction:

• It gains electrons.
• It acts as an oxidizing agent.
• It is reduced by a reducing agent.
• Its oxidation state or number decreases.

Hydration: Water Molecule Addition

The term hydration often refers to hydration reactions. This type of reaction involves the addition of one or more water molecules to a particular compound.

Hydrogenation: Adding Hydrogen to Compounds

Hydrogenation is a type of chemical redox reaction resulting in the addition of hydrogen (H₂) to another compound under...

Nuclear Physics

A branch of physics that studies the properties and behavior of atomic nuclei.

Historical Foundations

• Democritus: Formulated the theory that matter consists of indivisible particles called atoms (Greek atomos = indivisible).
• John Dalton: Proposed a new theory on the constitution of matter in 1803.
• Elements: Fundamental units called atoms, honoring Democritus.
• Compounds: Consist of molecules whose structure is formed by the union of atoms in definite and constant proportions.

Subatomic Discoveries

In the late nineteenth century, it was discovered that atoms are not indivisible but are composed of several types of elementary particles.

• Electron: The first particle discovered in 1897.
• Core: Composed of positively charged protons and neutrons,

Zinc Extraction and Processing

Dry Extraction Method

The dry way is used for ore concentrations greater than 10%. If the blende and calamine are crushed and calcined to produce zinc oxide, they are effectively tested and reduced with carbon in a muffle furnace. By releasing oxygen, a wealth of 98% zinc is obtained.

Humid Extraction Method

The humid way is used for concentrations less than 10%. The blende and the ore are crushed to obtain zinc ore powder. Sulfuric acid is added to produce zinc sulfate, and impurities from other elements are dissolved. Through electrolysis, the zinc sulfate is separated, and zinc is obtained at a purity of 99.9%.

Zinc Alloys and Applications

• Shape Alloys: Brass (Cu-Zn) replaces bronze; Alpaca (Cu, Ni, and Zn) is used

Redox Reactions

Oxidation: A process in which an atom, ion, or molecule loses electrons.
Reduction: A process in which an atom, ion, or molecule gains electrons.

An oxidizing agent is a substance that gains the electrons lost during oxidation. A reducing agent is a substance that donates electrons, which are then gained during reduction. In short, a reducer is an electron donor, and an oxidant is an electron acceptor. Every redox reaction must involve at least one oxidizer and one reducer.

Balancing Redox Equations

Historically, oxidation was defined as the gain of oxygen. For example, in the reaction CO + 1/2O₂ → CO₂, carbon monoxide acts as the reducer, and the process is oxidation. Today, we follow the electron-transfer concept, and reactions...

Elements and Compounds

Elements are substances consisting of a single type of atom. Compounds are substances obtained by the grouping of atoms of different elements.

A Little History

Chemical Elements for Life: Bioelements

Bioelements are the chemical elements of living beings. The most abundant species are: C, H, O, N, Ca, P, Mg, S, Na, K, and Cl, and they make up more than 99% of these living things.

Trace Elements

Trace elements are present in lower proportions (approximately 0.1%) and are indispensable for all living things, such as Fe, Zn, Mn, F, I, Cu, and Co.

The RDA (Recommended Dietary Allowance) is the amount of nutrient that a healthy person should eat each day on average, as part of the diet, to maintain good health.

Isolated Atoms

The elements...

Functions and Properties of Water

These properties are due to the polarity of the water molecule, which provides its solvent power, and the existence of hydrogen bonds.

Solvent Power

Thanks to the polarity of the molecule, water can be interposed between the ions in the crystal lattices of ionic compounds. This decreases the attraction between them and causes them to separate (dilution).

Liquid at Room Temperature

The great strength of cohesion between its molecules ensures that water remains liquid at normal temperatures. Thanks to this, water acts as a carrier in the body.

Incompressible Liquid

Due to the high degree of cohesion, the volume of liquid water does not decrease even when applying pressure.

Capillarity

Water molecules are held together...