Zadania z chemii IB SL

The amount of $\ce{NO2}$ prepared was checked by titration. The gas was first absorbed in water: $\ce{2NO2(g) + H2O(l) -> HNO3(aq) + HNO2(aq)}$ The resulting solution was made up to 200.0 $\mathrm{cm^3}$ in a volumetric flask, and 20.0 $\mathrm{cm^3}$ portions…

The student recorded the following masses. Sample Mass / g (± 0.01 g) Percentage by mass Mixture before separation 6.35 not applicable Iron after separation 2.58 Calcium carbonate after separation 1.71 Potassium chloride after separation 2.31 36.4 % Calculate…

Describe how a standard aqueous solution of potassium manganate(VII) can be prepared from the solid.

Describe the steps by which this standard solution is turned into a calibration curve for the colorimeter.

Explain how the calibration curve is then used to determine the concentration of $\ce{KMnO4}$ in a reaction mixture of unknown concentration.

Draw a line of best fit on the graph, extrapolating it beyond the range of the data.

State, in mathematical terms, how the absorbance of these solutions depends on their concentration.

Deduce the equation that relates absorbance to concentration for these solutions, including the numerical value of the constant.

Estimate the absorbance of a 0.400 $\mathrm{mol\,dm^{-3}}$ solution of nickel(II) sulfate.