1.1 Development of Chemistry and Its Importance
Chemistry is a field of science that studies the structure, properties, composition, and interactions between substances.
Meaning of Chemistry
The word chemistry originates from the Arabic word al-kimiya. Chemistry deals with all matter around us, including organic and inorganic substances.
Careers and Fields Related to Chemistry
- Medicine & Healthcare: Pharmacist, Doctor, Forensic Scientist, Toxicologist.
- Agriculture: Agronomist, Agricultural Chemist, Soil Scientist.
- Industry & Technology: Chemical Engineer, Materials Scientist, Food Technologist, Quality Control Chemist.
Chemical Chemicals in Daily Life
- Food: Preservatives (sodium benzoate), Flavourings (MSG), Colourings.
- Medicine: Antibiotics, Analgesics (Paracetamol), Antacids.
- Agriculture: Fertilizers (Urea, NPK), Pesticides, Herbicides.
- Cleaning Agents: Soap, Detergents, Disinfectants.
1.2 Scientific Investigation in Chemistry
Scientific investigation is a systematic method used by scientists to solve problems and discover knowledge.
Scientific Method Steps
- Making observations: Gathering information through senses or instruments.
- Asking questions: Identifying the problem based on observations.
- Formulating a hypothesis: Making a smart testable statement that predicts the relationship between variables.
- Identifying variables:
- Manipulated variable: Factor that is systematically changed.
- Responding variable: Factor that is measured/observed as a result.
- Fixed variable: Factors kept constant throughout the experiment.
- Designing an experiment: Planning materials, apparatus, procedure, and safety steps.
- Conducting the experiment: Executing steps accurately and systematically.
- Collecting data: Recording observations and measurements accurately in tables.
- Analyzing and interpreting data: Looking for trends, patterns, and mathematical relationships.
- Making conclusions: Deciding whether the hypothesis is accepted or rejected.
- Writing a report: Documenting the background, methodology, results, and discussion.
1.3 Action and Safety Measures in the Laboratory
Personal Protective Equipment (PPE)
- Goggles: Protect eyes from hazardous chemicals, splashes, or dust.
- Lab Coat: Protects clothing and skin against chemical spills.
- Gloves: Protect hands from corrosive, toxic, or hot substances.
- Face Mask: Protects respiratory system from fumes, fine powders, or vapors.
- Closed Shoes: Protect feet from spilled liquids or dropped glassware.
Laboratory Safety Equipment
- Fume Chamber: Designed to carry away toxic, volatile, or flammable gases.
- Safety Shower: Used to flush chemicals off body/clothing quickly in accidents.
- Eyewash Station: Used to rinse eyes thoroughly if contaminated by chemicals.
- Fire Extinguisher: Suppresses small laboratory fires.
- Laminar Flow Cabinet: Prevents contamination during microbiological manipulations.
Managing Chemical Accidents and Spills
- General Chemical Spills: Inform the teacher/lab assistant immediately. Secure the area, cover liquid spills with sand or inert absorbent material, and sweep up safely.
- Mercury Spills: Inform teacher/lab assistant immediately. Do NOT touch mercury. Sprinkle sulfur powder over the spill to react with mercury forming non-volatile mercury(II) sulfide. Contact the fire department/HAZMAT for specialized cleanup.
Hazard Symbols and Proper Storage
- Flammable: Keep away from heat, open flames, and sparks (e.g., ethanol, acetone).
- Corrosive: Causes severe burns to skin and eyes (e.g., concentrated sulfuric acid, sodium hydroxide).
- Toxic/Poisonous: Harmful or fatal if inhaled, swallowed, or absorbed (e.g., potassium cyanide, mercury).
- Reactive/Explosive: Unstable under certain conditions (e.g., sodium metal, ammonium nitrate). Store reactive alkali metals under paraffin oil.