Zadanie 40
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. HNO3 B. NO2• C. NO2− D. NO2+
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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. HNO3 B. NO2• C. NO2− D. NO2+
Which equation represents a propagation step in the radical substitution of ethane by bromine? A. Br2 → 2 Br ⋅ B. ⋅ C2H5 + Br ⋅ → C2H5Br C. C2H6 + Br ⋅ → C2H5Br + H ⋅ D. ⋅ C2H5 + Br2 → C2H5Br + Br ⋅
Which species can act as the electrophile in a substitution reaction with benzene? A. Br− B. Na+ C. OH− D. Br+
Which methods for separating the components of the given mixtures are correct? A. I and II only B. I and III only C. II and III only D. I, II and III
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 cm3 volumetric flask.
The student pipetted 25.00 cm3 of the potassium hydroxide solution into a conical flask and titrated it with nitric acid, HNO3(aq), of concentration 0.1250 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 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.
The student then used the potassium hydroxide solution standardized in 1c to titrate ethanoic acid, CH3COOH, whose concentration was not known. (i) Neutralizing 25.00 cm3 of the acid required 40.00 cm3 of the standardized…