Practice IB Chemistry Topic R2.2 How Fast? the Rate of Chemical Change with authentic exam-style questions for both SL and HL students. This question bank focuses on the exact syllabus content for R2.2 How Fast? the Rate of Chemical Change and mirrors Paper 1A, 1B, 2 style where relevant.
Get instant solutions, detailed explanations, and build confidence with questions aligned to IB examiner expectations.
The experiment focuses on investigating the relationship between temperature and the rate of evaporation of three different volatile liquids: methanol, ethanol, and propan-1-ol.
Three identical Petri dishes are labelled A, B, and C, each containing 3.0 cm³ of a different alcohol: methanol (A), ethanol (B), propan-1-ol (C). Each dish is placed inside a temperature-controlled chamber (e.g. warm water bath or incubator) at 60 °C. A digital balance is used to measure mass loss after 5 minutes of heating.
The following data were collected:
| Alcohol | Initial mass / g | Final mass / g | Temperature / °C |
|---|---|---|---|
| Methanol | 2.38 | 0.62 | 60 |
| Ethanol | 2.40 | 1.15 | 60 |
| Propan-1-ol | 2.55 | 1.98 | 60 |
Calculate the average rate of evaporation of methanol in .
Describe the relationship between molecular size and evaporation rate based on the data.
Suggest why propan-1-ol evaporates more slowly than ethanol, despite being under identical conditions.
State the main intermolecular force present in alcohols and explain its origin.
Identify the functional group common to all three alcohols.
Draw a full structural formula of ethanol.
Sketch and label a Maxwell-Boltzmann distribution curve for the ethanol sample at 60 °C. Indicate the activation energy for evaporation and the fraction of particles with enough energy to overcome it.
The reaction between sodium thiosulfate and hydrochloric acid forms a precipitate:
Describe a method to determine the rate of this reaction.
Suggest how temperature affects the time for the cross to disappear.
Explain this effect in terms of activation energy.
Hydrogen peroxide decomposes slowly at room temperature:
State one way to measure the rate of this reaction.
State how the rate of reaction changes as the reaction proceeds.
Explain your answer to part 2.
Which condition must hold true for a valid reaction mechanism?
Which statement correctly explains how a catalyst increases the rate of reaction?