Name:_________________________________________ Section________________________ Chemistry 104 Laboratory
University of Massachusetts Boston
Hexamminenickel(II) Chloride Synthesis
_______________________________________________________________________________ PRELAB ASSIGNMENT
Calculate the percent yield for the sample data shown on page 3.
In aqueous solution nickel ion Ni2+ is surrounded by six water molecules which are actually bonded to the central metal ion. This complex is called the hexaquonickel(II) ion. When aqueous nickel chloride is precipitated from solution, the nickel ions carry their six water molecules into the crystals and so solid nickel(II) chloride is hydrated, has the formula [Ni(H2O)6]Cl2, and is more properly called hexaquonickel(II) chloride. If ammonia is added to a solution of this salt, ammonia molecules compete with the water in bonding Ni2+ and because the ammonia forms a stronger bond than water, the ammonia replaces the water according to: [Ni(H2O)6]Cl2(aq) + 6 NH3(aq) → [Ni(NH3)6]Cl2(aq) + 6 H2O (l) or, as a net ionic equation
[Ni(H2O)6]2+(aq) + 6 NH3(aq) → [Ni(NH3)6]2+(aq) + 6 H2O (l) In this net ionic equation, the product [Ni(NH3)6]2+ is called hexamminenickel(II) ion. In this experiment we will synthesize the complex salt hexamminenickel(II) chloride. In the next experiment we will analyze for the percent ammonia in this salt. IN THE LABORATORY
1) Use an analytical balance to tare a weighing dish and then weigh out anywhere from 4.0 to 4.5 g of nickel chloride. Record the mass to a tenth of a milligram on the data sheet. 2) Dissolve your nickel chloride in roughly 10 mL of deionized water in a 250-mL beaker. Mark the beaker with your initials.
3) Slowly pour aqueous ammonia into your beaker up to the 50-mL line. Stir with a glass rod. After 15 minutes, cool in an ice bath stirring occasionally....
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