1.1 Science is Part of Everyday Life
Science is a discipline that involves systematic observation, experimentation, and explanation of natural phenomena.
Importance of Science in Daily Life
- Medicine: Development of vaccines, antibiotics, and advanced diagnostic machinery (MRI, X-ray).
- Agriculture: High-yield crop hybrids, automated irrigation systems, and pest control.
- Communication: Smartphones, high-speed fiber-optic internet, and satellite systems.
- Transportation: Electric vehicles, bullet trains, and aerospace engineering.
Fields of Science and Related Careers
- Biology: Study of living organisms. Careers: Botanist, Zoologist, Doctor, Microbiologist.
- Physics: Study of matter, energy, force, and motion. Careers: Engineer, Physicist, Astronomer.
- Chemistry: Study of substances, composition, and chemical reactions. Careers: Pharmacist, Forensic Chemist, Chemical Engineer.
- Geology: Study of rocks, minerals, and the Earth's structure. Careers: Geologist, Seismologist.
- Astronomy: Study of celestial bodies in outer space. Careers: Astrophysicist, Astronaut.
1.2 Your Science Laboratory
A science laboratory is a specialized room designed for conducting scientific experiments safely.
Common Laboratory Apparatus and Their Uses
- Beaker / Conical Flask: Holds liquids and chemicals in larger quantities.
- Measuring Cylinder: Measures the precise volume of liquids.
- Burette & Pipette: Measures exact liquid volumes accurately (Burette: variable up to 0.1 cm³; Pipette: fixed volume like 25 cm³).
- Test Tube / Boiling Tube: Holds small amounts of chemicals for testing or heating.
- Tripod Stand & Wire Gauze: Supports apparatus during heating and distributes heat evenly.
- Evaporating Dish: Evaporates excess solvent from a solution.
- Filter Funnel: Separates insoluble solids from liquids using filter paper.
Hazard Symbols
- Flammable: Easily catches fire (e.g., Ethanol, Petrol).
- Explosive: Explodes when heated or struck (e.g., Hydrogen gas, Ammonium nitrate).
- Corrosive: Burns skin and corrodes metals (e.g., Concentrated Hydrochloric acid, Sodium hydroxide).
- Toxic / Poisonous: Causes death or serious health issues if inhaled/ingested (e.g., Mercury, Cyanide).
- Irritant: Causes stinging, redness, or rash (e.g., Chloroform, Dilute ammonia).
- Radioactive: Emits harmful ionizing radiation (e.g., Uranium, Radium).
Bunsen Burner Flames
- Luminous Flame (Air hole CLOSED): Yellow color, unstable, produces soot, cooler temperature. Used when burner is idle.
- Non-luminous Flame (Air hole OPEN): Blue color, steady, sootless, hotter temperature. Used for effective heating.
1.3 Physical Quantities and Their Units
Physical quantities are properties that can be measured using standard units.
SI Units (Système International d'Unités)
- Length: Meter (m)
- Mass: Kilogram (kg)
- Time: Second (s)
- Thermodynamic Temperature: Kelvin (K)
- Electric Current: Ampere (A)
Prefixes for Physical Quantities
- Giga (G): $10^9 = 1,000,000,000$
- Mega (M): $10^6 = 1,000,000$
- Kilo (k): $10^3 = 1,000$
- Deci (d): $10^{-1} = 0.1$
- Centi (c): $10^{-2} = 0.01$
- Milli (m): $10^{-3} = 0.001$
- Micro ($\mu$): $10^{-6} = 0.000001$
- Nano (n): $10^{-9} = 0.000000001$
1.4 The Use of Measuring Instruments, Accuracy, Consistency, Sensitivity, and Errors
Definitions
- Accuracy: Closeness of a measured value to the true/actual value.
- Consistency (Precision): Ability of an instrument to yield the same reading repeatedly under identical conditions.
- Sensitivity: Ability to detect small changes in the measured quantity.
Types of Experimental Errors
- Systematic Errors: Constant errors occurring in every measurement due to faulty instruments or poor setup (e.g., Zero Error). Corrected by recalibrating or subtracting zero error.
- Random Errors: Uncertainties due to environmental changes or observer variations (e.g., Parallax Error). Minimized by taking multiple readings and calculating the average.
1.5 Density
Density ($\rho$) is defined as the mass per unit volume of a substance.
$$\text{Density } (\text{g/cm}^3 \text{ or kg/m}^3) = \frac{\text{Mass } (\text{g or kg})}{\text{Volume } (\text{cm}^3 \text{ or m}^3)}$$
Flotation and Sinking
- An object floats if its density is lower than the density of the surrounding liquid.
- An object sinks if its density is higher than the density of the surrounding liquid.
1.6 Steps in a Scientific Investigation
- Identify the problem
- Formulate a hypothesis (tentative testable statement)
- Control variables:
- Manipulated Variable: Factor altered intentionally.
- Responding Variable: Factor observed or measured.
- Constant Variable: Factors kept identical throughout.
- Plan the experiment
- Conduct the experiment
- Collect and record data
- Analyze and interpret data
- Draw conclusions
- Write the report