Benjamin Berke
Partners: Sam Weisman, Mylan Jarret
CHE 100L-6
11 March 2010
Analysis of an Antacid
Purpose
The purpose of this lab is to practice titration technique, observe and record the reaction between a
hydrochloric acid and commercial antacid tablet.
Procedure
In the first experiment the students rinsed the burets which were full of water with a NaOH solution
that way, the water would not contaminate the results and dilute the NaOH solution. Then they weighed
out approximately 0.2grams of Tums in an Erlenmeyer flask. The students added about 25ml of HCL
into the Erlenmeyer flask. To do so, we had a buret filled with HCL and we recorded the initial and
final readings on the calibrated buret, and record these results. Then the flask was swirled for about a
minute to ensure a complete reaction. 4-5 drops of phenolphthalein are added, this acts as a reagent to
show a color change when the titration is completed. The solution is put under the buret and the NaOH
was added until the solution goes to a light blue color.
The second experiment required students to perform a similar task, however this time with AlkaSeltzer. The process and steps were identical, except the color changes to a pink color.
After the results are recorded the students performed a series of calculation to find extra data about the
antacids.
Data/Calculations
Antacid Name
Cost per Package
Serving Size
Concentration HCL (M)
TUMS
$5.10
2 tablets
0.110 M
TUMS
Mass of Sample (g)
Final Buret Reading (mL)
Initial Buret Reading (mL)
Volume of HCL delivered (mL)
Mol HCL delivered (mol)
Final Buret Reading (mL)
Initial Buret Reading (mL)
Volume NaOH Delivered (mL)
Mol HCL Neutralized (mol)
Mol HCL Neut. By Antacid (mol)
Cost of Antacid Sample (4 S.F.) ($)
Tablets per Package
Mass of Tablet
Concentration NaOH
Trial 1
0.215
30.85
6.42
24.43
1.69 x 10-3
20.51
11.00
9.51
1.20 x 10-3
1.49 x 10-3
5.555 x 10-3
Trial 2
0.225
32.00
7.85
24.15
2.66 x 10-3
29.45
20.51
8.94
1.13 x 10-3
1.53 x 10-3
5.813 x 10-3
150 tablets
1.316 g
0.126 M
Trial 3
0.204
32.90
8.20
24.70
2.72 x 10-3
40.00
29.45
10.55
1.33 x 10-3
1.39 x 10-3
5.271 x 10-3
mmol HCL Neut. Per Serving (mmol)
Avg. mmol HCL neut. Per Serving (mmol)
Cost per mol HCL Neutralized ($)
Avg. Cost per mol HCL Neutralized ($)
14.67
3.73
13.22
14.89
3.80
3.77
16.77
3.79
Trial 1
e. Moles of HCL Delivered
(24.43𝑚𝐿) (
1𝐿
0.110𝑚𝑜𝑙 𝐻𝐶𝐿
)(
) = 2.69 𝑋 10−3 𝑚𝑜𝑙 𝐻𝐶𝐿
1000𝑚𝐿
1𝐿
i. Moles of HCL Neutralized
1𝐿
0.126 𝑚𝑜𝑙 𝑁𝑎𝑂𝐻
1𝑚𝑜𝑙 𝐻𝐶𝐿
(9.51𝑚𝐿) (
)(
)(
) = 1.20 𝑋 10−3 𝑚𝑜𝑙 𝐻𝐶𝐿
1000𝑚𝐿
1𝐿
1𝑚𝑜𝑙 𝑁𝑎𝑂𝐻
j. Moles HCL Neutralized by Antacid
2.69 𝑋10−3 𝑚𝑜𝑙 𝐻𝐶𝐿 − 1.20 𝑋10−3 𝑚𝑜𝑙 𝐻𝐶𝐿 = 1.49 𝑋10−3 𝑚𝑜𝑙 𝐻𝐶𝐿
k. Cost of Antacid sample
1 𝑡𝑎𝑏𝑙𝑒𝑡 1 𝑝𝑎𝑐𝑘𝑎𝑔𝑒
$5.10
0.215𝑔 (
)(
)(
) = $5.555 𝑋 10−3
1.316𝑔 150 𝑡𝑎𝑏𝑙𝑒𝑡𝑠 1 𝑝𝑎𝑐𝑘𝑎𝑔𝑒
l. mmol HCL Neutralized per serving
1.20 𝑋10−3 𝑚𝑜𝑙 𝐻𝐶𝐿 1000𝑚𝑚𝑜𝑙 1.316 𝑔 2 𝑡𝑎𝑏𝑙𝑒𝑡𝑠
(
)(
)(
)(
) = 14.67 𝑚𝑚𝑜𝑙 𝐻𝐶𝑙/𝑠𝑒𝑟𝑣𝑖𝑛𝑔
0.215 𝑔
1𝑚𝑜𝑙
1 𝑡𝑎𝑏𝑙𝑒𝑡 1 𝑠𝑒𝑟𝑣𝑖𝑛𝑔
n. Cost per mol HCL Neutralized
$5.555 𝑋 10−3
(
) = $3.73 /𝑚𝑜𝑙 𝐻𝐶𝐿
1.49 𝑋10−3 𝑚𝑜𝑙 𝐻𝐶𝐿
Antacid Name
Cost per Package
Serving Size
Concentration HCL (M)
ALKA-SELTZER
$9.78
2 tablets
0.110 M
ALKA-SELTZER
Mass of Sample (g)
Final Buret Reading (mL)
Initial Buret Reading (mL)
Tablets per Package
Mass of Tablet
Concentration NaOH
Trial 1
0.200
50.00
25.00
Trial 2
0.200
35.00
10.00
72 tablets
3.229 g
0.126 M
Trial 3
0.200
24.50
49.50
Volume of HCL delivered (mL)
Mol HCL delivered (mol)
Final Buret Reading (mL)
Initial Buret Reading (mL)
Volume NaOH Delivered (mL)
Mol HCL Neutralized (mol)
Mol HCL Neut. By Antacid (mol)
Cost of Antacid Sample (4 S.F.) ($)
mmol HCL Neut. Per Serving (mmol)
Avg. mmol HCL neut. Per Serving (mmol)
Cost per mol HCL Neutralized ($)
Avg. Cost per mol HCL Neutralized ($)
25.00
2.75 x 10-3
31.80
11.55
20.55
2.55 x 10-3
2.00 x 10-4
82.34
42.05
25.00
2.75 x 10-3
30.20
11.20
19.00
2.39 x 10-3
3.6 x 10-4
77.17
79.38
23.36
34.43
25.00
2.75 x 10-3
30.70
10.70
20.00
2.52 x 10-3
2.3 x 10-4
78.62
37.87
Trial 1
e. Moles of HCL Delivered
(25.00𝑚𝐿) (
1𝐿
0.110𝑚𝑜𝑙 𝐻𝐶𝐿
)(
) = 2.75 𝑋 10−3 𝑚𝑜𝑙 𝐻𝐶𝐿
1000𝑚𝐿
1𝐿
i. Moles of HCL Neutralized
(20.25𝑚𝐿) (
1𝐿
0.126 𝑚𝑜𝑙 𝑁𝑎𝑂𝐻
1𝑚𝑜𝑙 𝐻𝐶𝐿
)(
)(
) = 2.55 𝑋 10−3 𝑚𝑜𝑙 𝐻𝐶𝐿
1000𝑚𝐿
1𝐿
1𝑚𝑜𝑙 𝑁𝑎𝑂𝐻
j. Moles HCL Neutralized by Antacid
2.75 𝑋10−3 𝑚𝑜𝑙 𝐻𝐶𝐿 − 2.55 𝑋10−3 𝑚𝑜𝑙 𝐻𝐶𝐿 = 2.0 𝑋10−4 𝑚𝑜𝑙 𝐻𝐶𝐿
k. Cost of Antacid sample
1 𝑡𝑎𝑏𝑙𝑒𝑡 1 𝑝𝑎𝑐𝑘𝑎𝑔𝑒
$9.78
0.200𝑔 (
)(
)(
) = $8.41 𝑋 10−3
3.229𝑔 71 𝑡𝑎𝑏𝑙𝑒𝑡𝑠 1 𝑝𝑎𝑐𝑘𝑎𝑔𝑒
l. mmol HCL Neutralized per serving
2.55 𝑋10−3 𝑚𝑜𝑙 𝐻𝐶𝐿 1000𝑚𝑚𝑜𝑙 3.229 𝑔 2 𝑡𝑎𝑏𝑙𝑒𝑡𝑠
(
)(
)(
)(
) = 82.34 𝑚𝑚𝑜𝑙 𝐻𝐶𝑙/𝑠𝑒𝑟𝑣𝑖𝑛𝑔
0.200 𝑔
1𝑚𝑜𝑙
1 𝑡𝑎𝑏𝑙𝑒𝑡 1 𝑠𝑒𝑟𝑣𝑖𝑛𝑔
n. Cost per mol HCL Neutralized
$8.41 𝑋 10−3
(
) = $42.05 /𝑚𝑜𝑙 𝐻𝐶𝐿
2.0 𝑋10−4 𝑚𝑜𝑙 𝐻𝐶𝐿
Results
Avg. mmol HCL Neutralized per serving
Avg. cost per mol HCL Neutralized
TUMS
14.89mmol
$13.77
ALKA-SELTZER
79.38mmol
$34.43
More acid can be neutralized from Alka-Seltzer than Tums per serving according to the results. It was
also found that it costs less to neutralize a mole of acid in Alka-Seltzer than Tums from the data
recorded. It can be determined that Alka-Seltzer is the best deal as it neutralizes the most acid and costs
least. Average mmol HCl neutralized per serving is 79.38mmol for alka-seltzer, which cost $34.43, but
Tums cost $13.77 but only neutralized 14.89mmol, therefore was less effective. In order to get the same
effect as Alka-seltzer, Tums would end up costing more than the Alka-Seltzer.
Conclusion
The students were able to practice two titrations and analyze two types of commercial antacids.