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

Photoelectric Effect Explained

The photoelectric effect is the emission of electrons or other free carriers when light shines on a material. Electrons emitted in this manner are called photoelectrons.

Specifically, when light shines on a metal, electrons can be ejected from its surface. This phenomenon, where light waves hitting a metal surface cause electrons to be ejected, is a fundamental aspect of the photoelectric effect.

Chemical Bonds: Types and Strengths

Understanding Chemical Bonds: Strongest to Weakest

Chemical bonds are the forces that hold atoms together to form molecules. Here are three types, generally ordered from strongest to weakest:

1. Ionic Bonding

   Ionic bonding involves a transfer of an electron, where one atom gains an electron while

Questions

Answers

Why do you use distilled water in your experiments?

Because distilled water has all its impurities removed through distillation.

What is the formula for converting oC to Fahrenheit( F)?

(oC x 1.8) + 32

Formula for converting oF into Celsius

 (oF - 32)  1.8

Formula for converting oC to Kelvin(K)

K = oC + 273.15

Name all the volumetric apparatus used in the lab

Beaker, measuring cylinder, Burette, Pipet, and volumetric flask. (See the attachment)

A student got the following results in his experiment: 14.9g, 14.19g, 14.88g, 14.92g, but the actual weight is 20.90g. How accurate are the student results. And how precise are the results.

The student results are not accurate but precise. Has the precision of  0.05g

Sketch 2 pieces of glassware:

Kinetic Energy and the Nature of Matter

• Kinetic Energy: The energy an object possesses due to its motion.
• Kinetic Theory: States that all matter is composed of tiny particles in constant motion.

Pressure and Its Measurement

• Gas Pressure: Results from the force exerted by a gas per unit surface area of an object.
• Vacuum: An empty space devoid of particles and pressure.
• Atmospheric Pressure: Arises from the collisions of atoms and molecules in the air with objects.
• Barometer: A device used to measure atmospheric pressure.
• Pascal (Pa): The SI unit of pressure.
• Standard Atmosphere (atm): The pressure required to support 760 mm of mercury in a mercury barometer at 25ºC.

Phase Transitions and States of Matter

• Vaporization: The conversion of a liquid to a gas

Impact of Minimum CD & Treasury Bond Investment

Question: If the amount invested in CDs and treasury bonds is at least $5,000 plus 1.2 times the amount invested in municipal bonds and growth stocks, what is the new optimal solution and Optimal Feasible Value (OFV)?

Answer: Since the allowable increase is greater than $5,000 and this is a binding constraint, you must re-solve the problem to obtain the new optimal solution. The new OFV can be estimated using the shadow price: New OFV ≈ Old OFV + 5000 * (-0.0295).

Adding a GIC Investment Alternative

Question: If there is another investment alternative in Guaranteed Investment Certificates (GICs) with a Return on Investment (ROI) of 10%, what is the new optimal solution and OFV?

Answer: Introducing... Continue reading "Investment Portfolio Optimization: Sensitivity Analysis" »

Fundamental Science Concepts

1. Key Definitions in Chemistry and Physics

Match the word with its definition:

• Chemical Reaction: A process in which one or more substances (the reactants) are converted to one or more different substances (the products).
• Enzyme: Any of various proteins, originating from living cells, capable of producing chemical changes in organic substances.
• Catalyst: A substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.
• Viscosity: The state of being thick, sticky, and semifluid in consistency, due to internal friction.

2. Common Chemical Formulas

Write the chemical formula for the following substances:

• Water: H₂O
• Oxygen: O₂
• Hydrogen Peroxide: H₂O₂

3. Main Shapes of Bacteria

Identify... Continue reading "Essential Science Knowledge: Biology & Chemistry" »

Quantum Mechanical Rules for Electron Configuration

The Aufbau Principle

Electrons will fill the lowest available energy level first.

The Pauli Exclusion Principle

Each orbital can hold a maximum of two electrons, and they must have opposite spins.

Hund’s Rule (Rule of Maximum Multiplicity)

Orbitals of equal energy (degenerate orbitals) will fill with one electron at a time before pairing up. Single electrons in these orbitals should have the same spin.

Foundational Discoveries in Atomic Theory

Rutherford's Gold Foil Experiment

This experiment demonstrated that atoms possess a positively charged nucleus orbited by electrons. Very few positively charged alpha particles were greatly deflected back from the metal foil, indicating a small, dense, positive... Continue reading "Fundamental Principles of Atomic Structure and Quantum Rules" »

Mineral Definition and Fundamental Properties

Minerals are defined as: naturally occurring, inorganic, solids with a definite chemical composition, a regular crystalline structure, and specific and consistent physical properties. The fundamental aspects of this definition are a mineral's chemical composition, crystalline structure, and physical properties.

Different chemical compositions result in different minerals. A good example is the mineral plagioclase. Plagioclase is a member of the feldspar group, but there is more than one type. For instance, albite and anorthite are two examples. Albite has a chemical composition of NaAlSi₃O₈, while anorthite's chemical composition is CaAl₂Si₂O₈. Though very similar, their distinct compositions define... Continue reading "Mineral Identification: Properties and Structure" »

The Sun: Structure and Activity

Galileo's Solar Observations

Galileo Galilei was among the first scientists to study the Sun in detail (circa 1610).

Sun's Chemical Makeup

The Sun's composition is primarily Helium & Hydrogen.

Inside the Sun

Solar Atmosphere Layers

• Photosphere
• Chromosphere
• Corona

Solar Interior Zones

• Core
• Radiative Zone
• Convective Zone

How the Sun Produces Energy

Solar energy is produced by nuclear fusion in the core region, converting hydrogen into helium. This process is the source of the Sun's energy.

The energy output is approximately 9 × 10¹⁰ megatons of TNT per second.

Understanding Solar Wind

Solar Wind is solar material flowing into interplanetary space. The Sun's atmosphere is expanding radially outwards in all directions. Solar... Continue reading "Science Essentials: Sun, Matter, Physics" »