--%>
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 : Quantum Mechanical Operators The

    The quantum mechanical methods, illustrated previously by the Schrödinger equation, are extended by the use of operators. Or, w

    		•
  • Q : Precipitation problem On passing H 2 S 

    On passing H2S  gas through a solution of Cu+ and Zn+2 ions, CuS is precipitated first because: (i) Solubility product of CuS is equal to the ionic product of ZnS (ii) Solubility product of CuS is equal to the solubility product o

    		•
  • Q : Electrochemistry ( electrolysis of

    1. Define Faraday's first law of electrolysis 2. define Faraday's second law of electrolysis

    		•
  • Q : Question associated to vapour pressure

    Choose the right answer from following. The vapour pressure lowering caused by the addition of 100 g of sucrose(molecular mass = 342) to 1000 g of water if the vapour pressure of pure water at 25degree C is 23.8 mm Hg: (a)1.25 mm Hg (b) 0.125 mm Hg (c) 1.15 mm H

    		•
  • Q : Dipole moment of chloro-octane Describe

    Describe the dipole moment of chloro-octane in brief?

    		•
  • Q : Application of colligative properties

    Choose the right answer from following. Colligative properties are used for the determination of: (a) Molar Mass (b) Equivalent weight (c) Arrangement of molecules (d) Melting point and boiling point (d) Both (a) and (b)  

    		•
  • Q : Problem based on molecular weight

    Select the right answer of the question. Molecular weight of urea is 60. A solution of urea containing 6g urea in one litre is : (a)1 molar (b)1.5 molar (c) 0.1 molar (d) 0.01 molar

    		•
  • Q : Question on Mole fraction Mole fraction

    Mole fraction of any solution is equavalent to: (a) No. of moles of solute/ volume of solution in litter (b) no. of gram equivalent of solute/volume of solution in litters (c) no. of  moles of solute/ Mass of solvent in kg (d) no. of moles of any

    		•
  • Q : The three facts on the evaporation

    Describe briefly the three facts on the evaporation?

    		•
  • Q : Calculating Formulae Superphosphate has

    Superphosphate has the formula CaH4(PO4)2 H2O, what is the calculation to get the percentage of Phosphorus, I need to show the calculation. I know it is 30.9737622 u in weight and 2 atoms of the formula, but not sure how to work the calculation backwards.

    		•