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.