Zadania z chemii IB HL

Benzene undergoes nitration when it is warmed with a mixture of concentrated nitric and sulfuric acids. Which species attacks the benzene ring in this substitution reaction? A. $\ce{HNO3}$ B. $\ce{NO2}$• C. $\ce{NO2-}$ D. $\ce{NO2+}$

Which equation represents a propagation step in the radical substitution of ethane by bromine? A. $\ce{Br2 -> 2Br•}$ B. $\ce{•C2H5 + Br• -> C2H5Br}$ C. $\ce{C2H6 + Br• -> C2H5Br + H•}$ D. $\ce{•C2H5 + Br2 -> C2H5Br + Br•}$

Which species can act as the electrophile in a substitution reaction with benzene? A. $\ce{Br-}$ B. $\ce{Na+}$ C. $\ce{OH-}$ D. $\ce{Br+}$

Which methods for separating the components of the given mixtures are correct? Mixture Method I. Two miscible liquids with boiling points of 56 °C and 118 °C Distillation II. The coloured pigments extracted from a leaf Paper chromatography III. A solid…

Calculate the mass of solid potassium hydroxide that has to be weighed out.

Describe how the student should prepare this standard solution from the weighed solid using a 250.0 $\mathrm{cm^3}$ volumetric flask.

The student pipetted 25.00 $\mathrm{cm^3}$ of the potassium hydroxide solution into a conical flask and titrated it with nitric acid, $\ce{HNO3(aq)}$, of concentration 0.1250 $\mathrm{mol\,dm^{-3}}$. The burette readings before and after the titration are…

Using the concentration determined in 1c and the intended concentration of 0.1500 $\mathrm{mol\,dm^{-3}}$, calculate the percentage error in the concentration of the potassium hydroxide solution. If you have no value from 1c, take the concentration to be…

Explain why the potassium hydroxide solution has to be standardized before it is used in the titration. Assume that there are no systematic errors in the procedure.