Name _______________________________
The Amount of Sodium Hydrogen Carbonate in an Antacid Tablet
Prelab Questions
1. What are the bubbles released when Alka Seltzer is dropped into water? (5 points)
Carbon dioxide
2. What is the mole ratio between the moles of CO produced and the moles of NaHCO ?
2 3
(5 points)
3. Mass of the dry Alka Seltzer Tablet in grams. (5 points)
4. A student determines the mass of a 100 mL beaker filled with 50 mL of water to be 154.34
grams. After a tablet reacts with the water, the mass including the dissolved tablet is 157.26
grams. How much tablet was left in the beaker after the reaction? (10 points)
157.26 – 154.34 = 2.42 grams
5. The student in question 4 weighed the dry tablet before the reaction and found its mass to be
3.98 grams. Using the mass of the tablet that remained from question 4, what was the mass of
gas released? (5 points)
3.98 – 2.42 = 1.56
6. Using the data from problems 4 and 5 calculate the percentage of NaHCO in the tablet.
3
(5 points)
1:2
3.24 grams
2.42 / 3.98 = 0.60 = 60%
Data Collection
7. As you go through the lab record your data on the table below: (20 points)
Trial 1 2 3 4 5 6 7 8
Amount of
vinegar (mL)
0 5 10 15 20 25 30 35
Amount of
water (mL)
35 30 25 20 15 10 5 0
Beaker plus water
mass (g)
144.78 146.01 145.57 145.86 144.71 145.94 145.35 145.19
Mass of
tablet (g)
3.24 3.24 3.24 3.24 3.24 3.24 3.24 3.24
Beaker plus water
plus tablet mass
after bubbles stop (g)
147.45 148.54 147.90 148.23 147.08 148.24 147.55 147.55
8. Using information from the pre-lab and from your data collection, complete the table below.
You must show one calculation for each row or no credit will be awarded for this section. (15
points)
Calculations and Graphs:
Trial 1 2 3 4 5 6 7 8
Calculated mass
of NaHCO
3
reacted (g)
2.67 2.53 2.33 2.37 2.37 2.30 2.20 2.36
Calculated mass
of CO lost (g)
2
0.57 0.71 0.91 0.87 0.87 0.94 1.04 0.88
Calculated % by
mass of reacted
NaHCO3 in tablet
82% 78% 75% 73% 73% 71% 68% 73%
9. Sample calculation for mass of NaHCO reacted Ex. Show work for row 1, 1. (10 points)
3
147.45 – 144.79 = 2.67
2.67 grams
10. Sample calculation for mass of CO lost: Ex. Show work for row 2, trial 1. (10 points)
2
3.24 – 2.67 = 0.57
0.57 grams
11. Sample calculation for % by mass of reacted NaHCO in tablet: Ex. Show work for row 3, trial.
3
(10 points)
2.67 / 3.24 = 0.82
0.82 x 100 = 82
82 %
