Zadania z chemii IB SL

Before use, the EDTA solution was standardized against a standard solution of $\ce{Cu^2+}$ ions. An accurately weighed piece of pure copper wire was dissolved in the minimum volume of concentrated nitric acid and the mixture was warmed gently until no more…

Anhydrous copper(II) chloride, $\ce{CuCl2}$, takes up water vapour from the air, so it cannot be weighed out accurately to make a standard solution. Suggest a laboratory procedure that would remove all of the absorbed water from a sample of solid $\ce{CuCl2}$…

Portions of the rinse water were then titrated with the standardized EDTA solution in the presence of murexide as indicator. The burette readings are given in the table. Trial 1 Trial 2 Trial 3 Trial 4 Final burette reading / $\mathrm{cm^3}$ (± 0.05…

For the AAS method, a series of standards of known concentration was prepared by diluting a stock solution of $\ce{Cu^2+}$ ions. The instrument was zeroed with deionized water and the absorbance of each standard was recorded. (i) Draw the line of best fit for…

At room temperature hydrogen cyanide is a liquid that evaporates readily, whereas ethyne, $\ce{C2H2}$, which has almost the same molar mass, is a gas that boils at −84 °C. (i) Draw the Lewis formula of the hydrogen cyanide molecule, showing all valence…

In aqueous solution hydrogen cyanide behaves as a weak acid. (i) Write an equation for the ionization of hydrogen cyanide in water. (ii) Outline two ways in which a solution of 0.050 $\mathrm{mol\,dm^{-3}}$ $\ce{HCN}$ could be distinguished experimentally from…

A related nitrile, ethanenitrile, $\ce{CH3CN}$, reacts with hydrogen according to the equilibrium: $\ce{CH3CN(g) + 2H2(g) <=> CH3CH2NH2(g)}$ (i) Write the expression for the equilibrium constant, $K$, for this reaction. (ii) Determine the oxidation states that…

What is the number of hydrogen atoms in 0.0500 mol of hydrated magnesium sulfate, $\ce{MgSO4 * 7H2O}$? A. $3.01 \times 10^{22}$ B. $4.21 \times 10^{23}$ C. $2.11 \times 10^{23}$ D. $4.21 \times 10^{22}$