Cascadia Community College Stoichiometry and Limiting Reactant Lab

Chem 121Chemistry 121 Virtual Lab: Stoichiometry and Limiting Reactant
Description
The objective of this lab is to use stoichiometry to determine the concentrations of unknown solutions
through gravimetric analysis
Pre lab Questions
1. Write a balanced chemical reaction equation for solid sodium chloride added to aqueous silver nitrate.
2. Write out the net ionic equation for aqueous sodium chloride added to aqueous silver nitrate.
3. If 4.52g of the precipitate is formed, how many grams of sodium chloride reacted?
4. If a solution of 152 mL of sodium chloride reacted in question 3, what is the molarity of the sodium
chloride solution that was used?
Procedure
1. Clink on the link to navigate to the simulation. Link http://chemcollective.org/vlab/80
2. Click on the Limiting Reagent Problem 2 tab in the upper right corner of the page to read about
the objective of the investigation.
3. To begin your experiment, go to the “Stockroom” tab and add the following to the Workbench.
a. the Scale (Tools)
b. the Distilled water (Solutions)
c. the bottle of NaCl (Solutions)
d. the bottle of AgNO3 (Solutions)
e. solution 3 (Solutions, rename “unknown silver nitrate solution”)
f. solution 4 (Solutions, rename “unknown sodium chloride solution)”
g. a 100 mL volumetric flask (Glassware)
h. a 250 mL Erlenmeyer flask (Glassware)
i. a weigh boat
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Part A – Known solution
1. Place the weigh boat on the scale and Tare the scale. Use the “Sig Fig” method to measure out about 25
g of AgNO3 onto the weigh boat. Record the exact amount dispensed. Transfer the exact amount from
the weigh boat to the 100.0 mL volumetric flask. Add water to the 100.0 mL mark on the volumetric
flask. (Recall that the solid AgNO3 takes up some space, so you cannot add 100.0 mL to the flask.)
Calculate the molarity of the silver nitrate solution.
AgNO3 = ________ g
[AgNO3] = ________M
Helpful hint: If you go to “edit” you can change the name of your
glassware.
2. Place all of the AgNO3 solution into an Erlenmeyer flask. Note the “Information” panel to the left, and
pay close attention to the species/grams box. Using the “precise” method again, add solid NaCl in small
increments (1 g) to the AgNO3 solution. You should start to see AgCl(s) form in the flask and the
amount of AgCl shown in the Information panel to increase. Continue to add solid NaCl until the
amount of AgCl no longer increases when you add NaCl. Record the grams of AgCl that was formed.
AgCl (formed) = _______ g
3. Using the mass of AgCl you determined in step 2 and the balanced chemical reaction equation,
determine the mass of AgNO3 that must have been present in the initial solution (Use dimensional
analysis to calculate the AgNO3 mass). Use this amount to calculate the molarity of the AgNO3
solution.
Show your dimensional analysis calculation here:
Molarity calculation:
4. Confirm that the molarity is the same molarity that you calculated in step 1.
Part B – Unknown solutions
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Chem 121
Using a method similar to the one used in part A. Create and carry out a procedure for determining the
molarities of the unknown AgNO3 solution and the unknown NaCl solutions. Record your data and show
your calculations.
Unknown AgNO3
Unknown NaCl
Conclusion questions
1. If you have a company that is using this method to create AgCl, knowing that AgNO3 is an expensive
chemical, what do you think would be a better limiting reactant to use, AgNO3 or NaCl? Why?
2. Arcylonitrile, C3H3N, is the starting material for the production of a kind of synthetic fiber (acrylics)
and can be made from propylene, C3H6, by reaction with nitric oxide, NO, as follows:
______C3H6 (g) + ______NO (g) → ______C3H3N (s) + ______ H2O (l) + ______N2 (g)
Balance the above equation and determine what mass of C3H3N can be made when 21.6 g of C3H6 react
with 21.6 g of nitrogen monoxide (NO)?
3. The reaction equation for the reaction of baking soda (NaHCO3) with vinegar (HC2H4O2) is as follows:
_____ NaHCO3 + _____ HC2H3O2 →_____ NaC2H3O2 + _____H2O + _____CO2
If you have exactly 12.2 g of NaHCO3, how much HC2H4O2 (g) would you need to add to react all of the
NaHCO3?
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