Post Lab Assignment – Synthesis and Limiting Reactant
CHEM 131L Spring 2016
Include the following information at the top of the first page of your assignment:
Lab Partner Name:
Lab Section Number:
The entire report should be typed (handwritten portions will NOT be graded). Please
organize your report as shown below. You and your lab partner may not turn in the same
DATA & CALCULATIONS
Useful Information: The 25.0 wt % ethylenediamine solution contains 25.0 % ethylenediamine by
mass, dissolved in water, and has a density of 0.950 g/mL. First calculate the mass of the C2H8N2
solution from its volume and density, then calculate the mass of the C2H8N2 by remembering that
wt % solution =
mass of solute
mass of solution
From their masses and formula weights, you should then compute the number of moles of
NiCl2•6H2O and of C2H8N2 that were used. (Remember the formula weight of NiCl2•6H2O should
include the mass of the waters of hydration.)
1. Create a typed table that concisely presents the quantities (mass or volume as
appropriate for each reagent, as well as moles for all reagents) and appearance of both
of the reactants and the nickel product. (Remember to clearly label the table with a title
and headers for all data columns/ rows. Avoid blank cells in the table.)
2. What was the limiting reactant for your synthesis? Show your typed calculations.
3. What was the theoretical and percent yield of trisethylenediaminenickel(II) chloride for
your experiment? Show your typed calculations.
4. Assuming all of the limiting reactant was completely consumed (reacted), how many
moles of the other reactant (non-limiting) remained? Show your typed calculations.
QUESTIONS – All answers should be typed and answered in complete sentences.
1. What was the purpose of cooling the reaction mixture in an ice-water bath? Support
your answer with what you observed during this step of the synthesis.
2. Suggest at least one reason why a percent yield of less 100% would be obtained.
Use an actual observation from this experiment to support your answer.
3. During the purification of compound step, what would you expect to happen to the
percent yield of the product if a student washed the product with water rather than
acetone? Explain your answer.
4. During the purification of compound step, what would you expect to happen to the
percent yield of the product if a student only dried the product for 1 minute?
Explain your answer.
1. Consider the reaction:
MnO2 (s) + 4 HCl (g) MnCl2 (s) + Cl2 (g) + 2 H2O (g)
If 10.00 g of MnO2 and 10.00 g of HCl are reacted, how many grams of MnCl2 can
be produced? Show all calculations.
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