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Before use, the EDTA solution was standardized against a standard solution of Cu2+ 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, 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 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. (i) Suggest two reasons why trial 1 required a much larger volume of EDTA than the other…
For the AAS method, a series of standards of known concentration was prepared by diluting a stock solution of Cu2+ 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, 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 mol dm−3 HCN could be distinguished experimentally from…
The cyanide ion acts as a ligand in many complex ions, for example hexacyanoferrate(III), [Fe(CN)6]3−. (i) State the type of bond, as precisely as possible, that joins each cyanide ion to the iron ion. (ii) Deduce the oxidation state of iron in…
Cyanide ions react with bromoethane, CH3CH2Br. (i) Draw the full structural formula of the organic product of this reaction. (ii) Predict which mechanism, SN1 or SN2, operates in this reaction, and give a reason for your choice.…
What is the number of hydrogen atoms in 0.0500 mol of hydrated magnesium sulfate, MgSO4 ⋅ 7 H2O? A. 3.01 × 1022 B. 4.21 × 1023 C. 2.11 × 1023 D. 4.21 × 1022
(i) Suggest, giving a reason for each, two different safety precautions that should be taken when carrying out either of these preparations. (ii) Deduce the coefficients needed to balance the following equation for the reaction of silver with concentrated…