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

Aryl halide to diphenyl

Aryl halide reacts with sodium metal in the presence of dry ether to form diphenyl.

Name: Fittig reaction

Equations for SN1 step: tert‑butyl bromide to tert‑butyl alcohol

Equations for the step in SN1 of the conversion of tert‑butyl bromide into tert‑butyl alcohol.

IUPAC name for product from 2‑bromopentane with alcoholic KOH

IUPAC name for the major product obtained when 2‑bromopentane is heated with alcoholic KOH. Equation and name:

ANS: pent-2-ene

CH3-CH2-CH-CH3 ------> CH3-CH2-CH=CH-CH3

                     I

                   Br

NAME: elimination reaction

Why aryl halides are less reactive toward nucleophilic substitution

Aryl halides are less reactive towards nucleophilic... Continue reading "Key Organic Reactions: Fittig, Wurtz, Swarts, Kolbe‑Schmitt, Williamson" »

Hydrocarbon Classification and Properties

Chemical Categories

• Aliphatic: Chains/rings (Alkanes, Alkenes, Alkynes).
• Aromatic: Contains benzene ring.
• Derivatives: Organic. Atoms like O, N, halogens replace H.
• Inorganic: Oxides (CO₂, CO), Carbonates (CaCO₃, NaHCO₃), Carbides (CaC₂, SiC), Cyanides (NaCN).

Functional Groups

• Carboxylic Acid (-oic acid)

5. Describe what is electrodeposition, describe the different Experimental methods. Give examples. Advantages and disadvantages. It is the process of production a coating, usually Metallic, on a surface by the action of an electric current._Experimental Methods::-Electroplating: It is a plating process in which metal ions in a Solution are moved by an electric field to coat an electrode. Metallic cations From a solution are reduced on a conductive object (to form a thin layer).-Electrophoretic Deposition:Colloidal particles suspended in a liquid migrate under the Influence of an electric field (electrophoresis) and are deposited onto an Electrode._Advantages: uniform coating thicknen,easy control,high speed of Coating and high pucity._Disadvantages:

Challenges of Hydrogen Fuel Cells

The main issue with hydrogen fuel cells is that hydrogen is rarely found as a free element; it is usually found chemically combined with other elements, making it difficult to obtain.

• High cost: Due to this issue, producing, storing, and transporting hydrogen is expensive, and fuel-cell vehicles themselves cost more to make.
• Difficult storage: Hydrogen is very light and reactive, so it must be stored in strong tanks at very high pressures or extremely low temperatures, which is costly and complex. Its high reactivity means it can ignite easily, posing fire and explosion risks.
• Limited infrastructure: There are very few hydrogen refueling stations compared to gasoline or EV charging stations.
• Energy inefficiency:

Gas Chromatography Instrumentation and Analysis

1. Draw a block diagram of a GC instrument, labeling all the important components.

The components of a Gas Chromatography (GC) system follow this sequence:

• Mobile Phase Reservoir: Pressurized Helium (He) cylinder
• Sample Injector: Micro-syringe (located inside the oven)
• Stationary Phase: Column (located inside the oven)
• Detector: Thermal Conductivity Detector (TCD) or Flame Ionization Detector (FID)
• Readout: Computer system

2. What quantities are plotted on the x- and y-axes of (a) a chromatogram and (b) a calibration curve?

• a. Chromatogram: The x-axis represents time, and the y-axis represents the detector signal.
• b. Calibration Curve: The x-axis represents concentration, and the y-axis represents the peak

Fundamentals of Electrolysis

Electrolysis is the decomposition of a compound, in solution or in the molten state, brought about by the passage of electric current through it.

Definitions and Components

• An electrolyte is a substance in the molten state or as a solution in water, which allows the passage of electricity.
• A non-electrolyte is a substance in a solution that does not conduct electric current.
• A conductor is a substance which conducts or allows the passage of electricity.
• An insulator is a solid substance which does not conduct electricity.

Electrolysis Laws and Quantities

The amount of substance deposited or liberated is directly proportional to the quantity of electricity (Q) passed through the solution during electrolysis.

The moles of... Continue reading "Fundamentals of Electrolysis and Electrochemical Cells" »

Required Practical 1: Making Soluble Salts

Aim

To prepare a pure, dry sample of a soluble salt from an insoluble base, for example, making copper(II) sulfate from copper(II) oxide.

Method

1. Add excess copper(II) oxide to warm sulfuric acid and stir.
2. Filter the solution to remove the excess, unreacted base.
3. Gently evaporate the water from the filtrate to crystallize the salt.
4. Leave the solution to cool and then dry the resulting crystals.

Key Points to Remember

• Ensure excess base is used to neutralize all the acid.
• Avoid boiling the solution; use gentle heating to prevent it from spitting.
• Filter carefully to remove all unreacted solid for a pure salt solution.

Required Practical 2: Neutralization by Titration

Aim

To determine the concentration of an acid or... Continue reading "Essential Chemistry Practicals: Salts, Titration & Electrolysis" »

Atomic Structure and Electron Configuration

• Atomic number = number of protons
• Mass number = protons + neutrons
• Isotopes differ by the number of neutrons

Quantum Mechanics and Orbital Rules

• Orbitals: s (1 orbital), p (3), d (5), f (7)
• Aufbau Principle: Electrons fill the lowest energy orbitals first.
• Hund’s Rule: Electrons spread out before pairing up in orbitals.
• Pauli Exclusion Principle: No two electrons can have the same set of quantum numbers.

Photoelectron Spectroscopy (PES) Basics

• X-axis: Binding energy (values increase to the left).
• Peak height: Corresponds to the number of electrons.
• Position: Peaks farther to the left are closer to the nucleus.

Chemical

Part I: Temperature and Thermometers

Basic Concepts and Scales

1. Name the Three Scales of Temperature.

Ans: The three scales of temperature are:

• Celsius
• Fahrenheit
• Kelvin

2. How Are Temperature and Hotness Related?

Ans: Temperature and hotness of a body are directly related. The hotter a substance is, the higher its temperature.

3. Reading a Laboratory Thermometer: Eye Level Precaution

Ans: While reading the temperature on a laboratory thermometer, the eye must be at the level of the mercury in the stem to avoid parallax error and ensure an accurate reading.

4. How Does a Digital Thermometer Measure Temperature?

Ans: A digital thermometer does not use mercury. It utilizes internal heat sensors (such as a thermistor or thermocouple) to measure the temperature... Continue reading "Essential Science Q&A: Temperature, Thermometers, and Space Facts" »

Atomic Structure

• Protons — positive charge, found in nucleus
• Neutrons — no charge, found in nucleus
• Electrons — negative charge, orbit nucleus in energy levels

Key Terms

• Atomic Number (Z): number of protons
• Mass Number (A): protons + neutrons
• Isotopes: atoms of the same element with different numbers of neutrons
• Ions: atoms that gain or lose electrons
  • Gain electrons → negative ion (anion)
  • Lose electrons → positive ion (cation)

Important Formulas

• Mass Number: A = Z + N
• Average Atomic Mass: weighted average of all isotopes

Electron Configuration

Electrons fill energy levels from lowest to highest energy. Example: Oxygen (8 electrons) → 1s² 2s² 2p⁴

Types of Elements & Periodic Trends

Types of Elements

• Metals: shiny, conduct heat/electricity,