Brand of antacid
___________________________________________________________________
The
following were available:
Maalox, Mylanta, Milk of Magnesia, Rolaids, Tums, CVS Brand
Active ingredient
___________________________________________________________________
This was
indicated on the label. Most commonly antacids contain calcium
carbonate, magnesium hydroxide, aluminum hydroxide or sodium
hydrogen carbonate.
Amount of active ingredient _________________ Color of tablet
solution (if any) __________________
Total volume of HCl used to dissolve tablet
_______________________________________________
For most
students, this would have been 50.0 mL of the 0.500 M HCl
solution. If you required more than 50.0 mL, you were asked to
record how much additional HCl you used.
Number of moles of HCl added to tablet (show calculation):
The
Molarity of a solution represents the number of moles of
solute contained in 1.00 Liter of the solution. The HCl solution
you used to dissolved the tablet, therefore, contained 0.500 moles
of HCl in each liter of the solution. The molarity of a solution
can be used as a conversion factor between the volume of
the solution taken and the number of moles of solute present. For
50.0 mL of 0.500 M HCl, the number of moles of HCl present
is given by:
(50.0 mL) ×
(1.000 L/1000 mL) × (0.500 mol/1.000 L) = 0.0250 mol HCl taken
Initial volume of NaOH in the buret
_______________________________________________________
Final volume of NaOH in the buret
________________________________________________________
Volume of NaOH used from the buret
_____________________________________________________
Suppose
the initial volume reading of NaOH in my buret was 1.21 mL, and
the final volume at the color change was 41.35 mL. Then the volume
of NaOH used in the titration was
(41.35 mL -
1.21 mL) = 40.14 mL
Number of moles of NaOH added from the buret (show calculation)
I used
40.14 mL of 0.500 M NaOH: the number of moles of
NaOH used is therefore
(40.14 mL)
×
(1.000 L/1000 mL) × (0.500 mol/1.000 L) = 0.0201 mol to 3
significant figures
Number of moles of HCl not consumed by tablet (show
calculation)
The
number of moles of HCl not consumed by the tablet is
indicated by the number of moles of NaOH required in the
titration: 0.0201 mol of HCl was not consumed by the tablet.
Number of moles of HCl consumed by tablet (show
calculation)
We added
0.0250 mol of HCl to the tablet, and then found that 0.0201 mol of
HCl was not consumed by the tablet by titration with the
NaOH. So the amount of HCl that was consumed by the tablet
is
(0.0250 mol
taken) - (0.0201 mol not consumed) = 0.0049 mol HCl consumed by
the tablet
Mass of HCl (MM 36.5 g) consumed by tablet (show calculation)
(0.0049
mol HCl) × (36.5 g HCl/1 mol) = 0.18 g HCl
Compare
results for the mass of HCl consumed per tablet.
This is
just a place for you to write down the information that other
students provided on the blackboard. You should have at least 3
sets of data (your own, and the data for two different brands of
antacid provided by other students).
Cost
effectiveness
You are
given data about the cost of each antacid, how many tablets were
in each bottle, and the number of milligrams of active ingredient
in each tablet.
|
BRAND ANTACID
|
#
TABLETS
|
Mg
ACTIVE INGR.
|
COST
|
|
CVS
|
150
|
500
|
$2.99
|
|
Magnesia Tabs
|
200
|
311
|
$4.99
|
|
Maalox
|
35
|
1000
|
$3.99
|
|
Rolaids
|
75
|
550
|
$2.79
|
|
Mylanta
|
35
|
1000
|
$3.99
|
|
Tums
|
75
|
500
|
$2.99
|
For the
calculations shown earlier, it was found that for my tablet, the
tablet consumed 0.18 g of HCl. Suppose my tablet was a "CVS Brand"
from the table above. The cost of one CVS tablet is
($2.99/bottle) × (1 bottle/150 tablets) = 0.0199 $/tablet (about 2
cents per tablet)
the amount
of HCl consumed for this cost would be
(0.18 g
HCl/1 tablet) × (1 tablet/$0.0199) = 9.0 g HCl consumed per dollar
