I only need help answering the first question. I have been stuck o it for a whil
ID: 537880 • Letter: I
Question
I only need help answering the first question. I have been stuck o it for a while. I included the procedure of the lab just in case its needed. i already answered the other questions. But i would appreciate if you double check them.
28 NICKEL(IID SALT INTRODUCTION A nickel(II) salt is put into aqueous solution. Alcoholic dimethylglyoxime is added to this solution and the nickel(II) ion is then quantitatively precipitated as the bis(dimethylglyoximato)nickel(II) coordination compound. The salt's anion is a spectator in the reaction. CH, CH, 2+ Ni2+ + 2 CH (the dotted lines are hydrogen bonds or coordinate covalent bonds) The solid red nickel(II) dimethylglyoxime coordination compound is collected using suction filtration techniques and dried. The mass and formula of the precipitate are used to calculate the mass of Nickel in the original unknown salt. All mass determinations require the use of the analytical balance. PROCEDURE DAY 1 1. Obtain a capped shell vial containing an unknown nickel(II) salt. Record your unknown's number Place the vial of the nickel salt on the pan of the balance and then zero the balance with the vial on the pan. Carefully avoiding spills, the chemical is then transferred to the reaction vessel (for this experiment, use a clean 400 mL beaker which can be wet). The empty vial (which may have some chemical still clinging to its sides) is then returned to the balance pan (without re-zeroing). The negative mass displayed is the mass of nickel(II) salt transferred. 2. 3. Record the mass of nickel(II) salt transferred in grams to.1mg. Add approximately 200 mL of distilled water to the unknown sample in the 400 mL beaker. Using a clean glass or plastic stirring rod, stir the solution until all solids have been dissolved. 4. On a hot plate, heat the solution to between 60°C and 80°C (use a thermometer). Do not overheat!! 5. 6. 7. Add 4o mL of a 1-percent alcoholic solution of dimethylglyoxime to the warm solution. Stir well Using the dropper bottle of 6-M ammonium hydroxide (available in the hood) make the solution slightly basic (pH 8-9) by adding the 6-M ammonium hydroxide one drop at a time using a clean dropper After each drop, stir, and test the pH by touching the wet stir rod to a piece of pH paper. You should be able to do 4-6 tests on one piece of pH paper. Dispose of the used pH paper in the wastepaper basket, not on the floor nor in the sink!!Explanation / Answer
Question no. 1:
You are using a nickel salt. In the salt there is a counter anion present with Ni +2 . Suppose you are using nickel chloride (NiCl2 ). Here the counter anion is Cl-. Then from the reaction with dimethyl gyloxme and nickel chloride, the complex will be formed along with acid. The acid is HCl. It ionises as H+ and Cl- .
You are using ammonium hydroxide to make the solution basic. Ammonium hydroxide (NH4OH) which ionises as NH4+ and OH-
So, in the reaction reaction mixture, H+ , Cl-, NH4+ and OH- ions are present. You have to wash those ions before drying.