Question 1 · HL
| Substance | S° / J K⁻¹ mol⁻¹ |
|---|---|
| N₂(g) | 192 |
| H₂(g) | 131 |
| NH₃(g) | 193 |
From the standard entropies in the table, find ΔS° for N₂(g) + 3H₂(g) → 2NH₃(g).
Is IB Chemistry hard?
HL is a big step up from SL. At either level the hard part is the calculations and explaining why, not the facts.
| Syllabus content | 110 hours at SL, 180 at HL |
|---|---|
| Exams | 3 hours at SL, 4.5 hours at HL |
| HL-only topic | Entropy and spontaneity (Reactivity 1.4) |
| Internal assessment | 20%, the same at both levels |
What makes it hard
- Mole calculations run through every part of the course.
- Paper 1B is built on experimental data and uncertainties.
- Paper 2 explanations of trends, shapes and mechanisms.
SL or HL?
Medicine, pharmacy and chemical engineering courses often ask for chemistry; check whether yours ask for HL.
Try 2 questions
Question 2
The graph shows how the pH changes as 0.100 mol dm⁻³ NaOH(aq) is added to 25.0 cm³ of hydrochloric acid. What is the concentration of the hydrochloric acid?
Next step
Questions people ask
Is IB Chemistry HL harder than SL?
Yes: 180 hours of content against 110, an extra topic, more depth in the others and 4.5 hours of exams against 3.
Which part grows most at HL?
Reactivity 3, the mechanisms of chemical change: 45 hours at HL against 24 at SL.