General Chemistry 1 Principles and Formulas
Fundamentals and Measurements
- SI Units: Mass (kg), Length (m), Time (s), Temperature (K), Amount (mol), Volume (m³ or L = 10-3m³).
- Prefixes: Pico (10-12), nano (10-9), micro (10-6), milli (10-3), centi (10-2), kilo (103), mega (106).
- Density: d = mass / volume. To convert g/cm³ to kg/m³, multiply by 1,000 (e.g., 6.353 g/cm³ = 6,353 kg/m³).
- Temperature Conversions: °F = (9/5)°C + 32; K = °C + 273.15 (e.g., 56.1°C = 133°F).
- Significant Figures:
- Non-zero digits are always significant. Zeros between
Chemical Bonds, Polarity, and Molecular Geometry
The Fundamental Role of Chemical Bonds
Chemical bonds play an important role in the cells of all living things. They are essential for the existence of substances in materials, significantly affecting the structures and physical properties of elements and compounds.
Molecular Polarity and Dipole Moments
Molecules can be classified as polar or non-polar based on their total dipole moments. All diatomic molecules containing polar covalent bonds are polar molecules since they possess a net dipole moment.
Read MoreQualitative Inorganic Salt Analysis Procedures
Preliminary Tests
| Experiment | Observation | Inference |
| Color of the salt | Colourless | Absence of Cu2+, Fe2+, etc. |
| Odour of the salt | Ammoniacal smell Vinegar smell | NH4+ Acetate ion |
| Solubility | In water with no precipitate with Na2CO3 In dilute HCl, soluble | NH4+ No Group 1 cations |
| Salt is heated in a dry test tube | Colorless gas turns lime water milky Reddish brown fumes Smell of ammonia Pleasant fruity smell | Carbonate Nitrate ion NH4+ Acetate ion |
| Flame test | Pale green Brick red | Ba2+ Ca2+ |
| Ash test | Blue ash | Al3+ |
Systematic Analysis for Anions
| Experiment | Observation | Inference |
| Dilute |
Inorganic Chemistry Notes: Hydrides, Oxides & Metallurgy
Inorganic Chemistry Notes: Hydrides, Oxides & Metallurgy
Q1 — Diborane: Preparation, Structure & Bonding
Q1. Write a brief note on the preparation, structure, and bonding of diborane (B2H6). (6 marks)
Answer:
Diborane can be prepared by reducing boron trifluoride (BF3) with lithium aluminium hydride or by reacting sodium borohydride (NaBH4) with acids. The molecule consists of two boron atoms linked to four terminal hydrogen atoms and two bridging hydrogen atoms. The four terminal B–H bonds
Essential Chemistry Principles and Atomic Theory
1. Mathematics and Measurement in Chemistry
- Chemistry utilizes mathematics for measuring, calculating, and comparing data.
- It relies on SI Units (grams, liters, meters, Kelvin, etc.).
- Unit conversions are common (e.g., grams to kilograms).
- Accuracy and precision are critical in all experimental procedures.
Example: Measuring 25.0 mL of water provides precise data.
2. The Scientific Method and Data Analysis
- Steps: Ask a question → Form a hypothesis → Experiment → Collect data → Analyze → Conclude.
Understanding Coffee Brewing: Key Concepts and Techniques
1) Sensory Scoring Criteria
| Category | Focus | Sensory Indicators |
|---|---|---|
| Fragrance/Aroma | Smell before & after brewing | Floral, nutty, chocolatey, smoky; light roasts have brighter/fruitier notes, dark roasts are more smoky. |
| Flavor | Overall taste profile | Sweet, bitter, sour, complex |
| Aftertaste | Finish or lingering taste | Clean, smooth, or harsh |
| Acidity | Brightness, liveliness | Citrus, apple, wine-like |
| Body | Mouthfeel or texture | Light, medium, heavy |
| Balance | Harmony among traits | Well-rounded, even |
| Sweetness | Smoothness & pleasantness | Honey, |