IB Chemistry R2.2 How Fast? the Rate of Chemical Change Questionbank

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:

The reaction between sodium thiosulfate and hydrochloric acid forms a precipitate:

$\mathrm{N}{\mathrm{a}}_2{\mathrm{S}}_2{\mathrm{O}}_3(\mathrm{a}\mathrm{q})+2\mathrm{H}\mathrm{C}\mathrm{l}(\mathrm{a}\mathrm{q})\to 2\mathrm{N}\mathrm{a}\mathrm{C}\mathrm{l}(\mathrm{a}\mathrm{q})+\mathrm{S}(\mathrm{s})+\mathrm{S}{\mathrm{O}}_2(\mathrm{g})+{\mathrm{H}}_2\mathrm{O}($

Hydrogen peroxide decomposes slowly at room temperature:

$2\mathrm{H_2O_2(aq)} \rightarrow 2\mathrm{H_2O(l)} + \mathrm{O_2(g)}$

Which condition must hold true for a valid reaction mechanism?

Which statement correctly explains how a catalyst increases the rate of reaction?