ORG CHEM LAB (MIDTERMS)

Laboratory Apparatus

Funnel

  • Conical or tapered tube-like

  • Directs the flow of liquids or fine-grained substances from one container to another easily.

Beaker

  • Cylindrical container with a flat bottom

  • Used for holding and measuring liquids.

Stirring Rod

  • Used for mixing and stirring of liquids and solutions.

Erlenmeyer Flask

  • Conical-shaped glass container with a narrow neck

  • Utilized for mixing, heating, and containing liquids.

Spatula

  • Used for transferring solids and powders, as well as for scraping.

Volumetric Flask

  • Used for measuring specific liquid volumes with high accuracy.

Forceps

  • Also known as tweezers

  • Small handheld instruments for grasping and holding objects.

Test Tube

  • Small cylindrical container for holding and examining small amounts of liquids.

Tongs

  • Used for grasping and holding objects, especially when they are hot or need to be handled without direct contact.

Graduated Cylinder

  • Cylinder-shaped glassware for precise measurement and pouring of liquids.

Crucible

  • Used for heating substances to extreme temperatures, such as during melting, fusion, and calcination.

Pipette

  • Laboratory tool used to accurately measure and transfer small volumes of liquids for experiments.

  • For controlled liquid handling.

Syringe

  • Instrument used for injecting or withdrawing fluids from a container or a body.

Burette

  • Long, graduated glass tube with a stopcock at the bottom for controlled release of liquids.

Mortar and Pestle

  • Traditional tool used for grinding, crushing, and mixing substances into fine powders or pastes.

Petri Dish

  • Shallow lidded dish made of glass or transparent plastic used for cultivating and observing microorganisms.

Test Tube Rack

  • Used for holding and organizing multiple test tubes in an upright position.

Wash Bottle

  • Designed for dispensing small quantities of liquid, often used for rinsing equipment or samples.

Centrifuge

  • Device used to separate substances of different densities within a liquid mixture by subjecting the mixture to centrifugal force.

Bunsen Burner

  • Versatile tool used for heating solutions, sterilizing equipment, and conducting flame tests.

Litmus Paper

  • pH indicator used to determine if a solution is acidic or alkaline based on color change.

Thermometer

  • Measuring instrument for measuring temperature.

Weighing Scale

  • Digital measuring instrument for determining the weight or mass of substances.

Caliper

  • Measuring tool for accurately measuring dimensions of objects.

pH Meter

  • Scientific instrument used to measure the acidity or alkalinity of a solution.

Separation Techniques

  1. Filtration

    • Separates solids from liquids using a porous material.

    • Example: Removing coffee grounds from brewed coffee.

  2. Distillation

    • Separates liquids based on boiling points.

    • Example: Purifying water.

  3. Centrifugation

    • Rapid spinning separates substances of different densities.

    • Example: Separating blood components in a medical lab.

  4. Extraction

    • Separates compounds based on solubility in different solvents.

    • Example: Extracting caffeine from coffee beans.

  5. Crystallization

    • Purifies solids by dissolving them and forming crystals.

    • Example: Purifying sugar from a sugar solution.

  6. Sublimation

    • Separates a solid that turns directly into a gas, leaving impurities behind.

    • Example: Purifying iodine.

  7. Decantation

    • Separates a liquid from solids by pouring.

    • Example: Decanting water from settled sand.

  8. Evaporation

    • Separates solvent from a solution by heating until vaporization.

    • Example: Removing water from saltwater to obtain salt.

Preparing Solutions (Molarity)

  • Molarity (M): Concentration of a solution, defined as moles of solute per liter of solution.

  • Formula:[ M = moles of solute \ volume of solution (L)

Steps to Prepare a Molar Solution:

  1. Determine Moles of Solute Needed:

    • Use [ \text{moles of solute} = M \times \text{volume (L)} ]

  2. Calculate Mass of Solute:

    • Convert moles to grams using molar mass: [ \text{mass (g)} = \text{moles} \times \text{molar mass (g/mol)} ]

  3. Dissolve the Solute:

    • Weigh calculated mass and dissolve in a small amount of solvent (usually water).

  4. Dilute to Desired Volume:

    • Transfer to a volumetric flask and add solvent until final volume is reached.

    • Example: To prepare 1 L of a 0.5 M NaCl solution:

      • Moles of NaCl = 0.5 M x 1 L = 0.5 moles

      • Molar mass of NaCl=58.44 g/mol

      • Mass of NaCl=0.5 moles x 58.44 g/mol = 29.22 g

      • Dissolve 29.22 g of NaCl in water, then dilute to 1 L.

Dilution Formula

  • When diluting a concentrated solution, use: [ M1V1 = M2V2 ]

    • Where:

      • M1 and V1 are molarity and volume of concentrated solution.

      • M2 and V2 are molarity and volume of diluted solution.

Classification Test of Hydrocarbons (Properties)

1. Alkanes

  • General Formula: CnH2n+2

    • Combustion Test: Burns with a clean, blue flame, producing CO2 and H2O.

    • Bromine Test: No color change (remains orange), indicating no reaction.

2. Alkenes

  • General Formula: CnH2n

    • Bromine Water Test: Turns colorless due to addition reaction with double bond.

    • Baeyer Test (Potassium Permanganate): Purple color disappears, forming brown precipitate (MnO2).

3. Alkynes

  • General Formula: CnH2n-2

    • Bromine Water Test: Similar to alkenes; bromine water turns colorless.

    • Baeyer Test: Purple color disappears, indicating presence of triple bond.

4. Aromatic Hydrocarbons

  • General Formula: CnHn

    • Bromine Test: No color change (similar to alkanes).

    • Nitration Test: Forms yellow precipitate with concentrated HNO3, indicating electrophilic substitution.

5. Saturated vs. Unsaturated Hydrocarbons

  • Saturated Hydrocarbons: Contain only single bonds (alkanes).

    • Bromine Test: Shows no reaction.

  • Unsaturated Hydrocarbons: Contain double or triple bonds (alkenes and alkynes).

    • Bromine Test: Shows color change (decolorization).

Types of Chemical Reactions

1. Synthesis (Combination) Reaction

  • Description: Two or more reactants combine to form a single, more complex product.

  • General Form: A + B → AB

  • Example: 2H2 + O2 → 2H2O (formation of water)

2. Decomposition Reaction

  • Description: A complex compound breaks down into simpler substances.

  • General Formula: AB → A + B

  • Example: 2H2O2 → 2H2O + O2

3. Single Replacement (Displacement) Reaction

  • Description: One element replaces another in a compound.

  • General Formula: A + BC → AC + B

  • Example: Zn + CuSO4 → ZnSO4 + Cu

4. Double Replacement Reaction

  • Description: Two compounds exchange ions to form two new compounds.

  • General Formula: AB + CD → AD + CB

5. Combustion Reaction

  • Description: A substance reacts with oxygen to produce heat and light, often releasing CO2 and water.

  • General Formula: CxHy + O2 → CO2 + H2O

  • Example: CH4 + 2O2 → CO2 + 2H2O

6. Neutralization Reaction

  • Description: An acid and a base react to form water and a salt.

  • General Formula: HA + BOH → H2O + BA

  • Example: HCl + NaOH → NaCl + H2O

7. Redox Reaction (Oxidation-Reduction)

  • Description: Involves transfer of electrons between substances, where one is oxidized and the other is reduced.

  • General Formula: A + B → A^+ + B^-

  • Example: Sodium is oxidized, chlorine is reduced.

CHEMICAL EQUATIONS

  • The arrow (→) means: produces, reacts to produce, produced from, yields, yielding, decomposes, creating, making, synthesizes etc.