IB Chemistry SL case studies

IB Chemistry SL · Put your knowledge to work in context.

IB Diploma Programme Chemistry Standard Level is the standard-level chemistry subject within the IB Diploma Programme, typically taken by students aged 16–19 alongside other DP subjects. It is an academic qualification assessed by the IB, not a standalone professional licence, and it suits candidates who need a coherent chemistry foundation for university study in science, medicine, engineering or related fields, as well as students seeking a balanced science option. The IB Chemistry SL case studies are 5 cases and about 4,150 words.

Dumas-style molar mass: is the answer right for the wrong reason?

A student in an SL class determines the molar mass of a volatile unknown liquid using a flask method. She adds about 1 cm³ of the liquid to a clean, dry 268 cm³ conical flask (volume found by filling it with water from a burette, ±1 cm³), covers the mouth with a pierced bung, and stands the flask in a water bath at 99.0 °C until no liquid is visible.

831 words, about 4 min 2

Four unlabelled solids: which evidence is actually decisive?

Four solids are supplied unlabelled, each in a labelled vial, with the following data collected by a previous class: A: melting point 660 °C; conducts electricity in the solid state; can be hammered into thin sheets; insoluble in water. B: melting point 801 °C; does not conduct as a solid; conducts when molten; dissolves in water to give a conducting solution; shatters when struck.

811 words, about 4 min 3

Successive ionisation energies: identifying two Period 3 elements and testing two claims

Two Period 3 elements, X and Y, are supplied as samples with no labels. The class is given only their successive ionisation energies in kJ mol⁻¹: X: 578, 1817, 2745, 11578, 14831, 18378 Y: 738, 1451, 7733, 10540, 13630, 17995 A student writes: 'Y must be the more metallic of the two, because every one of Y's ionisation energies is higher than the corresponding one for X, so Y holds its electrons more tightly and will form positive ions more readily.' A second student writes: 'X shows a big jump between the third and fourth ionisation energies, which proves X has three electron shells.' The teacher asks the class to use the data to test both claims, to identify the two elements, and to predict how their oxides behave towards hydrochloric acid and towards sodium hydroxide solution.

809 words, about 4 min 4

An iodoform test that is positive for four different compounds

An unknown compound Z has the molecular formula C₄H₈O and boils at 79–80 °C. A student carries out four tests and records the observations: Bromine water shaken with Z: the orange colour persists.

725 words, about 4 min 5

Critiquing an IA: 'How does acid concentration affect the rate of reaction with magnesium?'

A student's internal assessment investigates: 'How does the concentration of hydrochloric acid affect the rate of its reaction with magnesium?' She uses 25.0 cm³ of acid at 0.50, 1.00, 1.50 and 2.00 mol dm⁻³ with a fresh 5.0 cm length of magnesium ribbon of mass 0.098 g (0.0040 mol) for each trial, at room temperature, and records the time for the gas syringe to fill with 40.0 cm³ of hydrogen (molar volume 24.0 dm³ mol⁻¹): 0.50 mol dm⁻³: 198 s; 1.00 mol dm⁻³: 96 s; 1.50 mol dm⁻³: 61 s; 2.00 mol dm⁻³: 47 s. She calculates 1/t for each and plots it against concentration.

974 words, about 5 min