--%>
Assignment Help - homework help

Help

1) Chromium(III) hydroxide is highly insoluble in distilled water but dissolves readily in either acidic or basic solution. Briefly explain why the compound can dissolve in acidic or in basic but not in neutral solution. Write appropriate equations to support your answer. 2) Explain how dissolving the Group IV carbonate precipitate with 6M CH3COOH, followed by the addition of extra acetic acid, establishes a buffer with a pH of approximately 5. 3) A solution contains either Cr3+ or Ni2+ ion. Describe the reaction with a single reagent that will identify which ion is present. 4) The addition of S2- ion to Fe(OH)2(s). Explain why the addition of S2- ion to Cr(OH)3(s) does not result in the formation of Cr2S3(s). 5) A black precipitate remaining from the separation of Cr3+ and Fe2+ ions from Ni2+ ion is dissolved in HCl HNO3. Some NH3 is added, followed by several drops of dimethylglyoxime. a) A colorless solution results. What do you think has happened? b) What might have gone wrong? 6) A student was analyzing an unknown containing only Group IV cations. When the unknown was treated with 3M (NH4)2CO3 solution, a white precipitate formed. Because the acetic acid bottle was empty, the student used 6M HCl to dissolve the precipitate. Following the procedure of this experiment, the student then added 0.10M K2CrO4 solution as directed and no precipitate formed. Oxalic acid was added to the solution, and no precipitate formed. a) What mistake did the student make? b) How did the mistake affect the tests for the cations in solution?

   Related Questions in Chemistry

  • Q : Number of electrons in the benzene

    Describe the number of electrons in the benzene? Write a short note on it?

    		•
  • Q : Problem on convection coefficient An

    An experiment to determine the convection coefficient associated with airflow over the surface of a thick stainless steel casting involves insertion of thermocouples in the casting at distances of 10 mm and 20 mm from the surface.  When the experiment was perform

    		•
  • Q : Molar mass of solute The boiling point

    The boiling point of benzene is 353.23 K. If 1.80 gm of a non-volatile solute was dissolved in 90 gm of benzene, the boiling point is increased to 354.11 K. Then the molar mass of the solute is: (a) 5.8g mol-1  (b)

    		•
  • Q : Show your calculations Superphosphate

    Superphosphate has the formulae: CaH4 (PO4)2H2).  Calculate the percentage of phosphorus in this chemical.  Show your calculations  (around ten lines);  also Work out how to make up a nutrient mixtur

    		•
  • Q : Molecular Diameters The excluded volume

    The excluded volume b, introduced by vander Wall's as an empirical correction term, can be related to the size gas molecules. To do so, we assume the excluded volume is the result of the pairwise coming together of molecules. This assumption is justified when b values

    		•
  • Q : Electrons present in a benzene How

    How many electrons are present in a benzene?

    		•
  • Q : Chemical formula of detergent Describe

    Describe the chemical formula of detergent?

    		•
  • Q : Einsteins mass energy relation In

    In Einstein’s mass energy relation e = mc2 for what is c employed or why is light needed for the reactions. As the reactions are with the help of neutrons?

    		•
  • Q : Question on Raoults law Give me answer

    Give me answer of this question. For a dilute solution, Raoult's law states that: (a) The lowering of vapour pressure is equal to mole fraction of solute (b) The relative lowering of vapour pressure is equal to mole fraction of solute (c) The relative lowering of v

    		•
  • Q : What is solvent dielectric effect?

    Ionic dissociation depends on the dielectric constant of the solvent.The Arrhenius that ions are in aqueous solutions in equilibrium with parent molecular species allows many of the properties of ionic solutions to be understood. But difficulties began to

    		•