Class 11 Chemistry Notes Chapter 1 (Chapter 1) – Lab Manual (English) Book

Detailed Notes with MCQs of Chapter 1 from your Chemistry Lab Manual, which covers Basic Laboratory Techniques. This is fundamental not just for your practical exams but also forms the basis for questions in various government competitive exams where basic science knowledge is tested. Pay close attention to the details, especially regarding safety, apparatus, and procedures.

Chapter 1: Basic Laboratory Techniques - Detailed Notes

1. Introduction to the Chemistry Laboratory

• Purpose: A chemistry laboratory is a place for experimentation, observation, and measurement. It allows verification of theoretical concepts through practical application.
• Importance of Preparation: Always read the experiment instructions before entering the lab. Understand the objective, procedure, chemicals involved, and precautions.
• Laboratory Notebook: Maintain a detailed record of every experiment, including date, aim, apparatus, chemicals used, procedure, observations, calculations (if any), results, and precautions. This is crucial for learning and reference.

2. Laboratory Safety Rules (Crucial for Exams)

• Personal Protective Equipment (PPE):
  • Safety Goggles: Always wear safety goggles to protect eyes from chemical splashes or fumes. This is non-negotiable.
  • Lab Coat/Apron: Wear a lab coat (preferably cotton) to protect clothing and skin.
  • Shoes: Wear closed-toe shoes. Sandals or slippers are strictly prohibited.
  • Gloves: Use appropriate gloves when handling corrosive or toxic chemicals.
• General Conduct:
  • Work silently and avoid distracting others.
  • No eating, drinking, or smoking in the laboratory.
  • Never taste any chemical.
  • Never smell chemicals directly. Waft the vapours gently towards your nose if smelling is necessary.
  • Keep your work area clean and organized.
  • Wash hands thoroughly before leaving the laboratory.
• Handling Chemicals:
  • Read labels carefully before using any chemical. Double-check the concentration.
  • Never return unused chemicals to the stock bottle (prevents contamination). Take only the required amount.
  • Handle concentrated acids (like H₂SO₄, HCl, HNO₃) and bases (like NaOH, KOH) with extreme care, preferably in a fume hood.
  • Diluting Acids: Always add acid slowly to water with constant stirring, never the other way around (highly exothermic reaction can cause splashing). A→W.
  • Keep flammable liquids (e.g., alcohol, ether) away from open flames.
• Handling Equipment:
  • Handle glassware carefully to avoid breakage. Check for cracks before heating.
  • Never heat graduated cylinders, measuring flasks, or thick-walled glass containers. Use beakers, conical flasks, or test tubes made of borosilicate glass (Pyrex/Borosil).
  • Point the mouth of a test tube being heated away from yourself and others.
  • Use tongs or test tube holders to handle hot objects.
  • Place hot apparatus on a wire gauze or ceramic tile, not directly on the bench.
• Waste Disposal:
  • Dispose of chemical waste as instructed. Do not pour solids or organic solvents down the sink unless permitted. Use designated waste containers.
  • Broken glassware should be disposed of in specific bins, not with general waste.
• Accidents and First Aid:
  • Report all accidents (cuts, burns, spills) to the instructor immediately.
  • Minor Cuts: Wash with water, remove glass pieces if any, apply antiseptic, and bandage.
  • Minor Burns: Hold the affected area under cold running water for several minutes. Apply burn ointment like Burnol.
  • Acid Spills on Skin: Wash immediately with plenty of cold water, then rinse with a dilute solution of sodium bicarbonate (baking soda).
  • Alkali Spills on Skin: Wash immediately with plenty of cold water, then rinse with a dilute solution of acetic acid (vinegar) or boric acid.
  • Eye Contamination: Wash the eye immediately and thoroughly with plenty of cold water using an eye-wash fountain for at least 15 minutes. Seek medical attention.

3. Common Laboratory Apparatus (Identification and Use)

• Beaker: Cylindrical glass container with a flat bottom and a lip for pouring. Used for holding, mixing, and heating liquids (not for accurate measurement). Available in various sizes (e.g., 100 mL, 250 mL, 500 mL).
• Conical Flask (Erlenmeyer Flask): Cone-shaped flask with a narrow neck. Used for heating, mixing, and titration (prevents splashing). Not for accurate volume measurement.
• Test Tube: Small cylindrical glass tube, rounded at one end and open at the other. Used for heating small amounts of substances and carrying out qualitative tests.
• Boiling Tube: Larger, thicker-walled test tube used for heating substances more strongly.
• Measuring Cylinder (Graduated Cylinder): Cylindrical glass container with markings (graduations) along the side to measure approximate volumes of liquids. Read the lower meniscus for colourless liquids and the upper meniscus for coloured liquids (like KMnO₄ solution) at eye level. Marked 'TC' (To Contain).
• Funnel: Cone-shaped apparatus used for transferring liquids or solids into containers with small openings and for filtration.
• Watch Glass: Concave piece of glass. Used to hold small amounts of solids for weighing or observation, or as a cover for beakers.
• Glass Rod: Solid glass rod used for stirring solutions and helping pour liquids without splashing.
• Wash Bottle: Plastic squeeze bottle with a nozzle, used to dispense distilled water for rinsing apparatus or adding small amounts of water.
• Tripod Stand: Metal stand with three legs, used to support apparatus (like beakers or flasks) over a Bunsen burner.
• Wire Gauze: Square piece of metal mesh, often with a ceramic centre. Placed on a tripod stand to ensure uniform heating of glassware.
• Bunsen Burner: Gas burner used as a heat source. Has adjustable air hole to control the flame type.
  • Luminous Flame: Yellow, sooty flame produced when the air hole is closed (incomplete combustion). Less hot.
  • Non-luminous Flame: Blue, roaring flame produced when the air hole is fully open (complete combustion). Hottest part is just above the inner blue cone. Used for strong heating.
• Test Tube Holder: Metal clamp used to hold a test tube, especially when heating.
• Tongs (Crucible Tongs): Metal tongs used to hold hot crucibles or other hot objects.
• Pipette: Glass tube used to deliver a specific, accurate volume of liquid (e.g., 10 mL, 20 mL, 25 mL). Marked 'TD' (To Deliver). Requires a pipette filler or bulb for drawing liquid (never use mouth). Rinsed with the solution to be measured before use.
• Burette: Graduated glass tube with a stopcock at the bottom. Used to deliver variable, accurately measured volumes of liquid, typically in titrations. Marked 'TD'. Read from top to bottom (0 mark at the top). Rinsed with the solution to be filled before use.
• Volumetric Flask (Measuring Flask): Flat-bottomed, pear-shaped flask with a long narrow neck marked with a line. Used to prepare a specific, accurate volume of a solution at a particular temperature. Marked 'TC'.
• Reagent Bottle: Glass bottle used to store chemicals (reagents). Clear glass for general chemicals, amber/brown glass for light-sensitive chemicals.
• Spatula: Small scoop used to transfer solid chemicals.

4. Basic Laboratory Techniques

• Cutting Glass Tubing:
  1. Place the glass tube flat on the bench.
  2. Make a single deep scratch with a triangular file at the desired point.
  3. Hold the tube with thumbs opposite the scratch.
  4. Gently pull and bend outwards; the glass should break cleanly at the scratch.
• Bending Glass Tubing:
  1. Heat the desired bending point in the non-luminous flame of a Bunsen burner, rotating the tube constantly for uniform heating.
  2. When the glass softens (flame turns yellow/orange), remove it from the heat.
  3. Bend it slowly and smoothly to the desired angle.
  4. Place it on a wire gauze or ceramic tile to cool.
• Fire Polishing: The sharp edges of cut glass tubes must be smoothed by heating them briefly in the flame until the edges become rounded. Prevents cuts and makes inserting into corks easier.
• Boring a Hole in a Cork:
  1. Select a cork borer slightly narrower than the tube to be inserted.
  2. Moisten the borer (with water or glycerol).
  3. Place the cork on the bench (wider end down).
  4. Press the borer vertically into the centre of the cork with a twisting motion.
  5. Remove the borer and push out the plug of cork.
• Inserting Glass Tube into a Cork:
  1. Ensure the glass tube end is fire-polished.
  2. Lubricate the tube end and the cork hole with water or glycerol.
  3. Hold the tube close to the end being inserted (wrap in cloth for safety).
  4. Gently push the tube into the cork with a slight twisting motion. Never force it.
• Heating Substances:
  • Liquids in Test Tubes: Fill less than one-third full. Hold with a test tube holder at an angle (~45°). Heat gently near the surface of the liquid, shaking occasionally. Point the mouth away from everyone.
  • Liquids in Beakers/Flasks: Place on a wire gauze on a tripod stand. Heat gently with a Bunsen burner. Add boiling chips for smooth boiling if needed.
  • Solids: Can be heated in test tubes, crucibles (for strong heating), or evaporating dishes (for evaporation).
• Filtration:
  • Purpose: To separate an insoluble solid from a liquid.
  • Procedure:
    1. Fold a circular filter paper into a cone shape (fold in half, then in quarters, open one side to form a cone).
    2. Place the filter paper cone in a funnel. Moisten it with the solvent (usually water) to make it stick to the funnel walls.
    3. Place the funnel on a filter stand with a beaker below the stem. The stem should touch the inner wall of the beaker to prevent splashing.
    4. Pour the mixture slowly down a glass rod onto the centre of the filter paper. Do not overfill the funnel (liquid level should be below the edge of the paper).
    5. The liquid passing through is the filtrate; the solid remaining on the paper is the residue.
• Weighing using a Chemical Balance (or Electronic Balance):
  • Ensure the balance is clean and level. Check the zero reading.
  • Never place chemicals directly on the balance pan. Use a watch glass or weighing paper.
  • Weigh the container (watch glass/paper) first (tare).
  • Add the substance carefully using a spatula until the desired mass is obtained.
  • Close the balance doors (if applicable) before taking the final reading to avoid air current effects.
  • Record the mass accurately.
  • Clean up any spills immediately.
• Measuring Volume Accurately:
  • Pipette/Burette: Rinse first with water, then with a small amount of the solution to be measured/filled. Fill the pipette above the mark using a filler, then adjust the level so the bottom of the meniscus touches the mark. For burette, ensure no air bubbles are in the nozzle; record initial reading (top of liquid level).
  • Reading the Meniscus: Position your eye level with the liquid surface. Read the bottom of the meniscus for colourless/transparent liquids. Read the top of the meniscus for coloured/opaque liquids (e.g., KMnO₄).
  • Accuracy vs. Precision: Accuracy is closeness to the true value. Precision is the closeness of repeated measurements to each other. Volumetric flasks, pipettes, and burettes are designed for high accuracy and precision. Measuring cylinders provide lower accuracy.

Multiple Choice Questions (MCQs)

1. When diluting concentrated sulphuric acid, the correct procedure is:
   a) Add water slowly to the acid.
   b) Add acid slowly to water with stirring.
   c) Mix acid and water rapidly.
   d) Add water and acid simultaneously in another container.

2. Which piece of apparatus is best suited for accurately measuring and delivering a fixed volume of 25.0 mL of a solution?
   a) 50 mL Beaker
   b) 25 mL Measuring cylinder
   c) 25 mL Volumetric pipette
   d) 50 mL Burette

3. The purpose of fire polishing the ends of a freshly cut glass tube is:
   a) To make it look shiny.
   b) To increase its length.
   c) To remove sharp edges and prevent cuts.
   d) To make it easier to heat.

4. While heating a liquid in a test tube, the mouth of the test tube should be pointed:
   a) Towards yourself.
   b) Towards your neighbour.
   c) Towards the ceiling.
   d) Away from yourself and others.

5. Which type of flame is produced by a Bunsen burner when its air hole is fully open?
   a) Luminous, yellow flame
   b) Non-luminous, blue flame
   c) Sooty, orange flame
   d) Smoky, yellow flame

6. Reading the volume of a colourless liquid in a burette or measuring cylinder should be taken from:
   a) The top of the meniscus.
   b) The bottom of the meniscus.
   c) The average of the top and bottom of the meniscus.
   d) Anywhere within the meniscus.

7. Which apparatus is marked 'TC' (To Contain) and is used for preparing solutions of known concentration?
   a) Burette
   b) Pipette
   c) Volumetric flask
   d) Measuring cylinder

8. In case of an acid spill on the skin, the first step should be:
   a) Apply an ointment immediately.
   b) Neutralize with concentrated alkali.
   c) Wipe it off with a cloth.
   d) Wash the affected area with plenty of cold water.

9. Filtration is a technique used to separate:
   a) Two miscible liquids.
   b) A soluble solid from a liquid.
   c) An insoluble solid from a liquid.
   d) Two immiscible liquids.

10. Before using a pipette to measure a specific solution, it should be rinsed with:
    a) Only distilled water.
    b) Only tap water.
    c) A small amount of the solution to be measured.
    d) Concentrated acid.

Answer Key for MCQs:

1. b
2. c
3. c
4. d
5. b
6. b
7. c (Note: Measuring cylinders are also TC, but Volumetric flasks are specifically for preparing accurate solutions)
8. d
9. c
10. c

Study these notes thoroughly. Understanding these basic techniques and safety protocols is essential for any practical science work and for answering related questions in your exams. Good luck!