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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…
A related nitrile, ethanenitrile, CH3CN, reacts with hydrogen according to the equilibrium: CH3CN(g) + 2 H2(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, 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…
The sealed vessel was left for the reaction to proceed. Suggest two properties of the system, other than its colour, that could be measured to follow the progress of the reaction over time, and predict how each would change as the forward reaction proceeds.
A sample of 0.0120 mol of NO2 was placed in a sealed vessel of volume 1.00 dm3, which was kept at a constant temperature of 35 °C. (i) Suggest a simple way of keeping the vessel at a constant temperature in a school laboratory. (ii) The…