Graphs Mastery 2 Check Hard Topic Unit 3,4

📊 10 Things to Know About AP Chemistry Graphs (Units 3 & 4)

❄️ Unit 3: Intermolecular Forces (Heating & Cooling Curves)

1. X-axis = time or energy input, Y-axis = temperature.
2. Flat regions = phase changes (q = m∆H).
3. Sloped regions = q = mc∆T.
4. Plateaus are longer for vaporization than fusion.
5. Each phase has its own slope depending on specific heat.
6. Used to calculate total energy required for full transitions.
7. Flat sections show intermolecular force disruption.
8. Higher boiling points mean longer vaporization regions.
9. Useful for understanding phase transitions and calorimetry.
10. Heating and cooling curves are reversible in theory.

🌍 Unit 4: Chemical Reactions (Beer's Law Graph)

1. Linear graph: Absorbance vs. Concentration.
2. Slope = molar absorptivity constant (ε).
3. Intercept = ideally zero, due to baseline correction.
4. Used in spectrophotometry analysis.
5. Assumes low concentration linearity.
6. Curved plots mean deviation from Beer’s Law.
7. Units of slope = L/mol·cm.
8. Essential for reaction rate monitoring by color change.
9. Relies on constant path length (usually 1 cm).
10. Equation form: A = εlc.