editing paper

Purpose:

The purpose of this experiment is to synthesize a mixed-metal nitrite complex,

K2BaNi(NO2)6, and illustrate the principles of reaction stoichiometry, stoichiometric calculations,

limiting reactants, and percentage yield.

Introduction:

Stoichiometry calculation are calculating the amounts of compounds or elements that re-

act and form a chemical equation and/or reaction. The word “stoichiometry” comes from the

Greek stoikheion which means “element” and metria which means “measure”. This all means

that the calculation is to measure elements. In this experiment, the synthesis of the hexanitrite

complex, K2BaNi(NO2)6, by the reaction of a solution including aqueous nitrite ions with an

aqueous solution of Ba2+ and Ni2+ ions. The ending reaction is here:

BaCl2 • 2H2O(aq) + NiCl2 • 6H2O(aq) + 6KNO2(aq) → K2BaNi(NO2)6(s) + 4KCL(aq) + 8H2O(l)

Procedure:

KNO2 is very toxic when ingested and is a strong oxidizing reactant. Make sure to take

care of skin, mouth, and eyes. Also, dispose the excess KNO2 in a way that it does not come in

contact with reducing agents. Metal salts are also toxic so waste containing metal ions should be

thrown away properly. Acetone is highly flammable.

To start, weigh out 1.2 g of BaCl2 • 2H2O and 1.2 g of NiCl2 • 6H2O. Record the exact

masses on the data sheet. Add the salts to a clean, dry 50mL beaker. Dissolve the two salts in

about 5-6mL of deionized water, with a hotplate on low to dissolve the salts. Secondly, to another

clean, dry 150mL beaker, add 4.25 g KNO2. Dissolve the KNO2 in 5mL of deionized water.

Again, record the exact mass on the data sheet. Once everything is dissolved, slowly add the

KNO2 solution, while stirring slowly, to the solution of the metal chlorides. After that, cool the

mixture in an ice bath and allow the solid to settle. Next, decant the supernatant liquid, leaving

the solid in the beaker where it can be washed more efficiently. Add a 10mL portion of deionized

water to the solid, stir well, and filter the solid by vacuum filtration collect the product. Record

the mass of the filter paper first. When the water has drained out of the filter paper, pour 5mL of

acetone over the solid to help it dry. Pour a second 5mL portion of acetone over the solid after

the first has completely drained through the filter. Complete the drying of your compound by

drawing a gentle stream of air through the filter and/or by placing in an oven on mild heat, but

this is if it is necessary. The product is dry when it appears powders and has no odor of acetone.

Lastly, determine the mass of the product by difference.

Results and Discussion:

The following experimental data was recorded:

1. Mass of BaCl2 • 2H2O: 1.26 g

2. Mass of NiCl2 • 6H2O: 1.24 g

3. Mass of KNO2: 4.24 g

4. Mass of filter paper: 0.54 g

5. Mass of filter paper + product: 3.17 g

6. Mass of product: 2.63 g

The theoretical yield was determined for the reaction. 
 1.26 g BaCl2 x 1 mol BaCl2 —————— = .006 mol BaCl2 208.27 g BaCl2 1.24 g x 1 mol NiCl2 —————— = .0052 mol NiCl2 237.71 NiCl2 4.24 g KNO2 x 1 mol KNO2 —————— = .0498 mol KNO2 85.11 g KNO2

The limiting reactant of the experiment was determined.

NiCl2

The percent yield for the reaction was determined. 


91.9%

2.63 g ———— x 100 = 91.9% 2.86 g

In this experiment, it was only minor errors that did not effect the outcome of the procedure.

Conclusion:

The synthesis of a mixed-metal nitrite complex was successfully determined. The theoret-

ical yield was determined to be 0.006 mol of BaCl2, 0.0052 mol of NiCl2, and 0.0498 mol KNO2.

The limiting reactant was determined to be NiCl2 since it was the smallest amount. The percent

yield for the reaction was 91.9% which is perfect.