Name:
Lab Partner:
Date:
Introduction to Stoichiometry Lab
Purpose: To determine the mole ratio of sodium bicarbonate to sodium chloride based on
the balanced equation.
Pre-Lab Questions
1. Write the balanced equation for the reaction between hydrochloric acid and sodium
bicarbonate (baking soda)
2. Convert 1.0 g of sodium bicarbonate to moles of sodium bicarbonate
3. The coefficients in a balanced equation represent the number of moles of the
respective substances in the reaction. Determine the following mole-to-mole ratios:
a) sodium bicarbonate to sodium chloride:
b) sodium bicarbonate to hydrochloric acid:
c) hydrochloric acid to carbon dioxide:
4. How many moles of sodium chloride should (theoretically) be produced during the
lab?
Procedure
1) Mass a clean, dry evaporating dish with watch glass.
2) Add about 1.0 g of sodium bicarbonate to the evaporating dish and mass.
3) Add the hydrochloric acid drop-wise using a plastic pipette until the fizzing stops. Use
the watch glass to prevent splattering.
4) Place the beaker with watch glass on a hot plate, and gently boil the water out of the
beaker. Keep heating until your product is dry
5) Mass the beaker and sodium chloride.
Data Table
1. Mass of Empty Evaporating Dish and Watch Glass (g)
2. Mass of Evaporating Dish, Watch Glass, and NaHCO3
(g)
3. Mass of NaHCO3 (g)
4. Moles of NaHCO3 (mol)
(Based on Pre-lab Q.2)
5. Mass of Evaporating Dish, Watch Glass, and NaCl (g)
6. Mass of NaCl (g)
7. Moles of NaCl (mol)
(Based on Box 6)
Calculation:
Analysis Questions
Directions: Show all work, and include all units
1. Calculate the ratio of moles of sodium bicarbonate to moles of sodium chloride
that you obtained in your experiment.
2. Based on the reaction written in the Pre-Lab, what is the actual mole ratio of
sodium bicarbonate to sodium chloride?
3. a) Using your answer to question 2, how many moles of sodium chloride should
you have theoretically obtained?
b) How many grams of sodium chloride should you have theoretically obtained?
(This is the “theoretical yield”)
c) How many grams of sodium chloride did you actually obtain? (This is the
“actual yield”)
d) We often express yields (amounts of product formed) in terms of a percentage.
The percent yield calculation reflection how much of the theoretical amount was
actually produced. Calculate the percent yield of sodium chloride.
Actual yield (g) x 100%
Theoretical yield (g)
4. How many moles of H2O should have theoretically been produced, based on the
number of moles of sodium bicarbonate you started with?
5. How many moles of CO2 should have theoretically been produced, based on the
number of moles of sodium bicarbonate you started with?
6. Suppose you started the lab with 5.5 grams of sodium bicarbonate.
a) Convert this mass to moles:
b) Determine the number of moles of sodium chloride you would expect to
produce
c) How many grams of sodium chloride would you expect to produce?
7. If you wanted to produce exactly 0.75 mol of NaC1, what mass of NaHCO3 would
you start with (assuming a "perfect" procedure)?
8. Suppose you did not evaporate all of the water out of your sodium chloride. How
would this affect the results?
9. Why were bubbles produced during the reaction?