Overview
The lecture covers key chemistry concepts for the CIH exam, focusing on isotopes of hydrogen, solution calculations, unit conversions, gas laws, and problem-solving strategies.
Hydrogen Isotopes
- The three main hydrogen isotopes are protium, deuterium, and tritium.
- Protium has 1 proton, deuterium has 1 proton and 1 neutron, and tritium has 1 proton and 2 neutrons.
Solution Calculations and Unit Relationships
- 1 gram per milliliter (g/mL) is a standard density unit.
- Cubic centimeters (cm³) and milliliters (mL) are equivalent units (1 cm³ = 1 mL).
- Moles of solute in a solution = Molarity (M) × Volume (L).
- Moles can also be calculated as grams divided by molecular weight (g/MW).
- Specific gravity (SG) is typically measured in g/mL or g/L.
Concentrations and Conversions
- To convert milliliters to milligrams, use substance density if needed.
- Parts per million (ppm) values are used for measuring concentrations, e.g., 682,000 ppm.
- Common conversions involve using constants like 24.45 for molar volume at standard conditions.
Gas Laws and Calculations
- Calculate gas volume changes using ideal gas law and convert between liters and cubic meters (1 m³ = 1,000 L).
- When pressure decreases, gas volume increases, and vice versa.
- Ideal gas constant and temperature conversions (Fahrenheit to Kelvin) are important for calculations.
Percentage and Fraction Calculations
- 3/10 is equivalent to 0.3 or 30%.
- Converting between decimals, fractions, and percentages is common in data interpretation.
Problem-Solving Skills for CIH Exam
- CIH exam questions may require selecting the correct formula based on a word problem.
- Recognizing when to use specific equations is critical for success.
- Showing work clearly and understanding unit conversions will help avoid common calculation errors.
Key Terms & Definitions
- Isotope — Atoms of the same element with different numbers of neutrons.
- Molarity (M) — Moles of solute per liter of solution.
- Molecular Weight (MW) — Sum of atomic masses in a molecule, used in mole calculations.
- ppm (parts per million) — A unit for measuring dilute concentrations of substances.
- Specific Gravity (SG) — Ratio of the density of a substance to the density of water.
- Ideal Gas Law — Equation relating pressure, volume, temperature, and moles of a gas (PV=nRT).
- Alveoli — Tiny air sacs in the lungs, relevant for gas exchange calculations.
Action Items / Next Steps
- Practice solution calculations using molarity and molecular weight.
- Review gas law problems and ensure understanding of unit conversions.
- Familiarize yourself with typical CIH exam question formats.
- Prepare any assigned homework or problems for next class.