Quantitative Determination of Sodium Bicarbonate
Intro
Some antacids and pain relievers is dissolved in water and produces sodium bicarbonate.
Many of these Effervescents contain citric acid in them which reacts with the sodium
bicarbonate and produces Carbon Dioxide gas. There is a loss of mass due to this acidbas reaction which is catalyzed in water. Due to this idea, one can determine the loss of
mass and one can calculate the amount of sodium bicarbonate that reacted and thus you
can determine the percent of mass of sodium bicarbonate in the tablet.
Objective: To begin understanding how scientist determine the quantative measurements
in Chemistry
Hypothesis: How much do you think is in the tablet? What is the percent
Materials:
- Effervescent tablets
- Vinegar
- Beakers
- Balance
- Graduated Cylinder
Procedure:
- Obtain a small beaker, weigh, and record the mass
- Measure 35mL of water into a small beaker, record the mass of beaker and the water
-Determine the mass of the water
-Weigh the tablet and record the mass
-Place one tablet in the water
- when the bubbles stop, stir to ensure completion
-Reweigh the Beaker and record the mass
- Repeat with 30mL of water and 5 Ml of acetic acid in the cup *Note Teacher may have
you change this amount- we will pull our class results
Data Table: You construct your own
Calculations:
-Determine the amount that was released in the reaction (Final Mass – Initial mass
of tablet)
-Then Divide the Mass you found in the previous step by the total mass of the
tablet
-Repeat for all the reactions for the whole class- I need to see your work! So
don’t just copy from one another
-Include another column in your chart for these calculations
- Prepare a graph of percent by Mass of sodium bicarbonate as a function of
volume of vinegar used
Questions
- Write out the formula for sodium bicarbonate
- Is sodium bicarbonate covalent or ionic? How do you know
- If you have citric acid in the effervescent, why did we use acetic acid in the
reaction?
- Why must you stir the mixture be stirred after the reaction is completed?
- Does the percent of sodium bicarbonate vary in different tablets
- Carbon dioxide dissolves in water and water evaporates into the atmosphere
during the experiment. How do these two factors affect the results of your
analysis
- Why do we use a base when we have an upset stomach? Think about your
biology
- What is a limiting reagent
- Does the humidity play any roll in the experiment?