Question 1
| Element | Percentage by mass / % |
|---|---|
| iron | 69.9 |
| oxygen | 30.1 |
The table gives the percentage composition by mass of an oxide of iron. What is its empirical formula?
The chemistry syllabus: SL and HL, part by part
Six parts, 22 topics: 180 hours of content at HL against 110 at SL.
26 weeks at SL, 104 hours in all
Start with Reactivity 3
What are the mechanisms of chemical change?: 20.9 of your hours. It is 24 of the 110 hours of SL syllabus content, 22%.
| Part | Your hours | Share of the syllabus |
|---|---|---|
| Reactivity 3: What are the mechanisms of chemical change? | 20.9 | 22% |
| Reactivity 2: How much, how fast and how far? | 18.3 | 19% |
| Structure 2: Models of bonding and structure | 17.5 | 18% |
| Structure 1: Models of the particulate nature of matter | 14.8 | 15% |
| Structure 3: Classification of matter | 14 | 15% |
| Reactivity 1: What drives chemical reactions? | 10.5 | 11% |
Week by week
- Week 1Reactivity 3: What are the mechanisms of chemical change?
- Week 2Reactivity 3: What are the mechanisms of chemical change?
- Week 3Reactivity 3: What are the mechanisms of chemical change?
- Week 4Reactivity 3: What are the mechanisms of chemical change?
- Week 5Reactivity 3: What are the mechanisms of chemical change?
- Week 6Reactivity 3: What are the mechanisms of chemical change?, Reactivity 2: How much, how fast and how far?
- Week 7Reactivity 2: How much, how fast and how far?
- Week 8Reactivity 2: How much, how fast and how far?
- Week 9Reactivity 2: How much, how fast and how far?
- Week 10Reactivity 2: How much, how fast and how far?, Structure 2: Models of bonding and structure
- Week 11Structure 2: Models of bonding and structure
- Week 12Structure 2: Models of bonding and structure
- Week 13Structure 2: Models of bonding and structure
- Week 14Structure 2: Models of bonding and structure
- Week 15Structure 2: Models of bonding and structure, Structure 1: Models of the particulate nature of matter
- Week 16Structure 1: Models of the particulate nature of matter
- Week 17Structure 1: Models of the particulate nature of matter
- Week 18Structure 1: Models of the particulate nature of matter, Structure 3: Classification of matter
- Week 19Structure 3: Classification of matter
- Week 20Structure 3: Classification of matter
- Week 21Structure 3: Classification of matter
- Week 22Structure 3: Classification of matter, Reactivity 1: What drives chemical reactions?
- Week 23Reactivity 1: What drives chemical reactions?
- Week 24Reactivity 1: What drives chemical reactions?
- Week 25Timed SL Paper 1 practice, then review every miss
- Week 26Timed SL Paper 1 practice, then review every miss
| Paper 1 | Paper 1A multiple choice and Paper 1B data-based questions: 1.5 hours at SL, 2 hours at HL, 36% |
|---|---|
| Paper 2 | Short answer and extended-response questions: 1.5 hours at SL, 2.5 hours at HL, 44% |
| Scientific investigation | Your own investigation, a report of at most 3,000 words: 20% |
| Teaching hours | 150 at SL and 240 at HL, as for every Diploma subject |
What HL adds
Entropy and spontaneity (Reactivity 1.4) is HL only, and every part goes deeper. Reactivity 3 grows most: 45 hours against 24.
The practical side
40 hours at SL, 60 at HL, including the collaborative sciences project and the scientific investigation (10 hours each).
Try 2 questions
Question 2
The graph shows the concentrations in the equilibrium H₂(g) + I₂(g) ⇌ 2HI(g) at constant temperature. What change was made at 10 min?
Next step
Questions people ask
What is the difference between IB Chemistry SL and HL?
HL has 180 hours of content against 110, an extra topic on entropy, more depth throughout and longer papers: Paper 1 is 2 hours against 1.5, Paper 2 is 2.5 hours against 1.5.
When was the current chemistry syllabus first examined?
In 2025, organised as Structure 1 to 3 and Reactivity 1 to 3.
Are there options in IB Chemistry?
No. Every student takes all six parts, with more at HL.