Zadania z chemii IB SL

At 25 °C the density of heavy water, $\ce{^{2}H2O(l)}$, is $1.11\ \mathrm{g\,cm^{-3}}$, while the density of ordinary water, $\ce{^{1}H2O(l)}$, is $1.00\ \mathrm{g\,cm^{-3}}$. Which statement explains this difference? A. Each $\ce{^{2}H}$ nucleus contains one…

Identify two controlled variables in this investigation.

The iron(II) concentration is found by titrating against a standard solution of potassium manganate(VII), $\ce{KMnO4}$. At intervals of a few days, a 20.00 $\mathrm{cm^3}$ sample is withdrawn from each flask and made up to 250.0 $\mathrm{cm^3}$ with water;…

The following readings are recorded during one titration. Final burette reading = $23.20 \pm 0.05\ \mathrm{cm^3}$ Initial burette reading = $3.20 \pm 0.05\ \mathrm{cm^3}$ Calculate the percentage uncertainty in the volume of $\ce{KMnO4}$ solution delivered…

The student's results are shown in the graph. (i) Calculate the average rate at which the iron(II) concentration fell in the 24 h flask during the 21 days. Include units. (ii) Before starting, the student proposed the hypothesis: "The longer a solution is left…

Suggest one way of extending the investigation so that further recommendations about storing the iron(II) solution could be made.

In the Geiger–Marsden experiment, α-particles (the nuclei of helium-4 atoms) were fired at a very thin foil of silver. A detector that could be moved around the foil recorded the angle of deflection, θ, of the particles. Two of the possible routes are shown:…

Lithium can be identified in the light emitted by stars and by flames containing lithium compounds. (i) Outline the appearance of the emission spectrum of lithium. The emission spectrum of a one-electron species, such as the $\ce{Li^2+}$ ion, can be explained…