IB Chemistry HL 2.1.2 Mole Ratio Questions

Use real HL exam questions to convert between masses, moles, volumes and concentrations with balanced-reaction ratios.

Exam points

Use a balanced equation to convert the amount of one reactant or product into the stoichiometric mole amount of another chemical species.
Calculate moles from mass, concentration or volume before applying the balanced-equation mole ratio and report the requested amount or volume.
State the mole ratio in the requested direction with named chemical species and retain units through the final mass, volume or concentration conversion.

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Study 2.1.2—Mole ratio conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

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Two groups of students (Group A and Group B) carried out a project* on the chemistry of some group 7 elements (the halogens) and their compounds.

The students reacted ICl(l) with CsBr(s) to form a yellow solid, $\mathrm{CsICl}_{2}(\mathrm{~s})$ , as one of the products. $\mathrm{CsICl}_{2}(\mathrm{~s})$ has been found to produce very pure CsCl(s) which is used in cancer treatment.

To confirm the composition of the yellow solid, Group A determined the amount of iodine in 0.2015 g of $\mathrm{CsICl}_{2}(\mathrm{~s})$ by titrating it with $0.0500 \mathrm{moldm}^{-3} \mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}(\mathrm{aq})$ . The following data were recorded for the titration.

Table for Question IB Chemistry HL 2.1.2 Mole Ratio Questions question 1 — IB Chemistry HL

The overall reaction taking place during the titration is:

Calculate the amount, in mol, of iodine atoms, I , present in the sample of $\mathrm{CsICl}_{2}(\mathrm{~s})$ .

$\left(0.5 \times 1.21 \times 10^{-3}\right)=6.05 \times 10^{-4} / 0.000605(\mathrm{~mol})$ ;

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IB Chemistry HL 2.1.2 Mole Ratio Questions question 1