Zadania z chemii IB HL

(a) The graph shows how the water level of the Salton Sea has changed since 1950. The reference point for the water level is sea level. (i) Suggest a reason why the values plotted on the vertical axis are negative. (ii) Describe the general trend in the rate…

(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…

What will be the volume of 4.00 dm3 of gas that has had the pressure decreased from 150 kPa to 50.0 kPa, and its temperature increased from 27.0 °C to 127 °C? A. 16.0 dm3 B. 12.0 dm3 C. 56.4 dm3 D. 1.78 dm3

(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…

(e) The propanoic acid obtained by the distillation was an aqueous solution with a volume of 22.5 $\mathrm{cm^3}$. Three 5.00 $\mathrm{cm^3}$ samples of this solution were titrated with 0.200 $\mathrm{mol\,dm^{-3}}$ $\ce{NaOH}$ to determine the accurate…