Notes, summaries, assignments, exams, and problems for Chemistry

Polyatomic Ions

• PO₄^-3 = Phosphate
• NO₃^-1 = Nitrate
• NO₂^-1 = Nitrite
• CrO₄^-2 = Chromate
• SO₄^-2 = Sulfate
• CO₃^-2 = Carbonate
• SO₃^-2 = Sulfite
• MnO₄^-1 = Permanganate
• HCO₃^-1 = Bicarbonate
• CH₃CO₂^-1 = Acetate
• ClO₄^-1 = Perchlorate
• ClO₃^-1 = Chlorate
• OH^-1 = Hydroxide
• CN^-1 = Cyanide
• NH₄⁺¹ = Ammonium

Naming Mineral Acids

• HF = Hydrofluoric Acid
• HCl = Hydrochloric Acid
• HBr = Hydrobromic Acid
• HI = Hydroiodic Acid

Naming Oxacids

• HNO₂ = Nitrous Acid
• H₂SO₃ = Sulfurous Acid

Diatomic

• N₂, O₂, F₂, Cl₂, Br₂, I₂

Metric Conversions

• Giga^9
• Mega^6
• Kilo^3
• Base = 1
• Deci^-1
• Centi^-2
• Milli^-3
• Micro^-6
• Nano^-9
• Pico^-12

Atomic Models

• Bohr: Based on the assumption that electrons travel in specific shells around the nucleus. Did not work for systems with more than 1 electron.
• Rutherford: Theorized that atoms have their

Scientific Method

Ask a question.

Research.

Make a hypothesis.

Experiment and test your hypothesis.

Analyze your test results.

Present a conclusion.

Chemistry

Chemistry is the branch of science that studies the properties of matter and how matter interacts with energy.

Organic Chemistry

The branch of chemistry concerned with the study of compounds that contain the element carbon.

Inorganic Chemistry

The branch of chemistry concerned with the study of materials that contain any combination of chemical elements.

Element

A substance that cannot be broken into two or more simpler substances by any physical or chemical method and made of the same kind of atoms.

Compound

A molecule of a pure substance that contains two or more elements combined.

Heterogeneous Mixture

A... Continue reading "Scientific Method and Chemistry: An Introduction to Matter and Atoms" »

Halogenation

Halogenation: The reaction of an alkane with a halogen (X2 = F, Cl, Br, I) occurs when a mixture of the two is irradiated with ultraviolet light.

Combustion

Combustion: The reaction of an alkane with O2 occurs during combustion when the alkane is used as a fuel. Carbon dioxide and water are formed as products, and a large amount of heat is released.

An example of a combustion reaction:

CH4 + 2 O2 → CO2 + 2 H2O + Energy

Complete

Complete: C2H6 (g) + O2 (g) → CO2 (g) + H2O (g) + Energy

Incomplete

Incomplete: C3H8 (g) + O2 (g) → H2O (g) + CO2 (g) + CO (g) + C (s) + Energy

Petroleum

Petroleum: Complex mixture of alkanes that can be separated into fractions by distillation. Separating molecules based on differences in boiling points is called... Continue reading "Halogenation, Combustion, Complete and Incomplete Reactions, Petroleum, Refining, Alkenes" »

Water Properties and Ocean Chemistry

Water's High Heat Capacity

21. Coastal Climate Moderation

Which property of water causes coastal communities to have only moderate differences in daily highs and lows when compared to inland communities?

Answer: A) High heat capacity.

22. Water's Heat Capacity Compared to Other Liquids

In comparison to most other liquids, the heat capacity of water is:

Answer: A) Higher than other liquids.

Seawater Composition and Buffering

23. Principle of Constant Proportions

The Principle of Constant Proportions states that:

Answer: D) The relative concentration of seawater ions does not change.

25. Seawater Buffer Ion

The ion in seawater that serves as a buffer is:

Answer: D) HCO3-.

Water Phase Changes

24. Temperature Change During

Water Quality Definitions

Alkalinity

Alkalinity: A measure of the water’s capability to absorb hydrogen ions without significant pH change (buffering capacity).

Problem 7-4: Settling Tank Design for Stillwater Water Plant Expansion

Design the settling tank(s) for the City of Stillwater’s water treatment plant expansion using the design overflow rate found in Example 7-3. The maximum day design flow is 0.5 m³/s. Assume a water temperature of 10° C.

Design Calculation Steps (Set 1)

1. Find the Surface Area

   Calculation: (0.5 m³/s) × (86,400 s/d) = 43,200 m³/d

2. Select the Number of Tanks

   

   = 221.66 or 222 m²/tank

3. Select a Trial Width for Calculation

   The maximum width for the chain-and-flight sludge collector is 6 m increments. Assume a width of 4 m.

4. Check

Metal Corrosion

Corrosion is the rusting of metal or alloy due to moisture and air. When it contacts air and water, a reaction forms a layer on the surface. For example, when an iron rod contacts air and moisture, it reacts and forms ferric oxide (Fe₂O₃) on its surface. It can be prevented by using alloys like stainless steel, brass, or bronze, painting the metal, applying oil, or coating with galvanized zinc.

Chemical Reactions

Some reactions happen very fast, like the precipitation of silver chloride, which occurs immediately after mixing aqueous solutions of silver nitrate and sodium chloride. Other reactions, like the rusting of iron in the presence of air and moisture, are very slow. Some reactions have a moderate rate.

The rate of a chemical... Continue reading "Metal Corrosion, Chemical Reactions, and Electrochemistry" »

Scalars and Vectors

What is a scalar? A scalar is a quantity that is fully described by a magnitude only. It is described by just a single number. Some examples of scalar quantities include speed, volume, mass, temperature, power, energy, and time.

What is a vector? A vector is a quantity that has both a magnitude and a direction. Vector quantities are important in the study of motion. Some examples of vector quantities include force, velocity, acceleration, displacement, and momentum.

Endothermic and Exothermic Reactions

An endothermic reaction takes place when energy is absorbed from the surroundings in the form of heat. An exothermic reaction is when energy is released from the system into the surroundings.

Endothermic reactions must be supplied... Continue reading "Scalars, Vectors, Endothermic & Exothermic Reactions Explained" »

Atomic Structure

Elements are a type of atom. Atoms are made up of protons, neutrons, and electrons. The nucleus is the center of an atom.

• Proton: +1 charge
• Electron: -1 charge
• Neutron: 0 charge (neutral)

Rutherford (1911) conducted the gold foil experiment.

Different elements have different numbers of protons in the nucleus.

• Atomic number (Z): Number of protons
• Mass number (A): Number of protons + Number of neutrons

Z

Chemical Symbol

A

Neutron number = Mass number - Atomic number

The number of neutrons can change (protons stay the same) in a given atom, making them isotopes.

Atomic mass is the total mass of elements and all its isotopes. U represents atomic mass units.

A radioactive isotope consists of nuclides whose nuclei undergo spontaneous decay.

Three

Physical States of Matter

Physical States: Solid (Stones, salt, copper) / Liquid (Water, alcohol, gasoline) / Gaseous (Nitrogen, oxygen, hydrogen)

Do they have a fixed shape? Yes/No/No. Do they have a fixed volume? Yes/Yes/No. Are they easily compressible? No/No/Yes. Do they expand? No/No/Yes.

Kinetic Theory of Matter

Kinetic Matter is formed by very small particles (atoms) that are invisible even when using microscopes. The particles are in continuous movement. The higher the temperature, the faster they move. There are forces of attraction between the particles that make them group together. The farther the distance between the particles, the stronger these forces become.

States of Movement of the Particles:

• Speed of movement: Low, medium, high.