Zadania z chemii IB HL

(b) A variety of ions are dissolved in the water of the Salton Sea. The concentrations of the major ions are shown in the table below, based on two different sources (both scientific journals). Ion Concentration / $\mathrm{g\,dm^{-3}}$, based on Source 1…

(c) A simple set-up was used to compare the conductivity of water samples obtained from the Salton Sea at different depths. The following data were obtained: Depth water sample was obtained from / m ($\pm 0.05\ \mathrm{m}$) Electric current recorded by the…

(a) Outline two features of this experiment that ensure that the propanal intermediate is not a major product.

(b) Outline two safety precautions that must be taken during the preparation of propanoic acid, besides wearing a lab coat and safety goggles.

(c) After 30 minutes, the student stopped heating the mixture and titrated a sample of the solution remaining in the flask with NaOH to determine the experimental yield of propanoic acid. Explain why the titrated sample will give an incorrect value for the…

(d) The student used distillation to obtain pure propanoic acid from the reaction mixture. (i) State two impurities, apart from unreacted propan-1-ol, that were present in the propanoic acid before distillation. (ii) The approximate experimental yield of…

Explain how the 0.2000 $\mathrm{mol\,dm^{-3}}$ solution is prepared in a volumetric flask from the weighed solid.

Suggest how to prepare 100.0 $\mathrm{cm^3}$ of a 0.05000 $\mathrm{mol\,dm^{-3}}$ sodium thiosulfate solution from the 0.2000 $\mathrm{mol\,dm^{-3}}$ solution.

A second student repeated the experiment with the same five solutions and the same apparatus and obtained the following times. Concentration of $\ce{Na2S2O3}$ / $\mathrm{mol\,dm^{-3}}$ Reaction time / s (± 0.1 s) 0.2000 ± 0.08 % 20.1 0.1000 ± 0.2 % 37.5 0.0500…