CHEM 121 Exp. ArBg due today NAME_____________________________________________
NOTE: Pbar (in DP) = # in Hg (in DP) X 25.4 mm/in -18 mm Hg
1. Bring this experiment sheet to your instructor who will select a reactant set # for your experimental
procedure. The reactants are sodium or potassium hydrogen carbonate and 0.80 or 0.60 M sulfuric acid.
The products are sodium or potassium sulfate, carbon dioxide, and water. Rinse off any contact with
sulfuric acid.
Set
0.80 M Sulfuric acid
Set
0.60 M sulfuric acid
1 Sodium hydrogen carbonate
3 Sodium hydrogen carbonate
2 Potassium hydrogen carbonate
4 Potassium hydrogen carbonate
2. __________________________________________________________________________
Write the balanced chemical equation showing your (circled) set↑.
3.  Gas molar volume = __________ Use the ideal gas law to calculate the molar volume (volume of
1.0 mol) of any gas under your laboratory conditions: (P =____________ and T = _____________)
[20L/mol <molar volume<30L/mol]
4.  Vbag = __________________ Check your zip-lock bag for leakage by adding some water (~50mL)
to the bag and sealing it. Move the water various places and squeeze the bag slightly to see if there is
leakage. If you are satisfied there is no leakage, measure the total bag volume in liters (L) using a known
volume of water. Write the bag volume (in L) in the blank. A graduate cylinder measures water volume
more accurately than other glassware.
Calculate the stoichiometric amounts of each reactant needed to fill the bag with carbon dioxide:
5. _________________ g of sodium or potassium hydrogen carbonate. Your answer (in grams) should
be less than 5 X the volume of the bag (in liters).
6. _________________ mL of 0.80 or 0.60 M sulfuric acid. Your answer (in mL) should be less than 40
X the volume of the bag (in L). HINT: Calculate the # L of sulfuric acid using molarity and # moles
sulfuric acid.
Note: I will check steps 5 & 6; be sure they are correct.
PROCEDURE: NOTE: YOU MAY WISH TO DO A TRIAL RUN.
7. Place the white solid first in one corner of the bag and the sulfuric acid in the other corner of the bag
prior to reaction for the two experiments described below. CLOSE THE BAG AND PLACE THE BAG
WITH THE REACTING MIXTURE IN THE SINK.
____________________ React the sodium or potassium hydrogen carbonate ( #5) with excess sulfuric acid
(#6 + 2 mL). NOTE: Sodium or potassium hydrogen carbonate is the limiting reactant.
____________________ React the sulfuric acid (#6) with excess sodium or potassium hydrogen carbonate
( #5 + 2g). NOTE: Sulfuric acid is the limiting reactant.
.
NOTIFY THE INSTRUCTOR WHEN YOU ARE READY FOR AN EVALUATION: DO NOT TOUCH
THE BAG IN THE SINK DURING EVALUATION WHEN THE REACTION HAS BEGUN. THE
INSTRUCTOR WILL EXAMINE AND DETERMINE HOW WELL YOU SUCCEEDED (1-4 points).
The bag must NOT be limp or break. The bag must be taut (full of gas)., and the solution must be clear (not
cloudy).
DRY AND RETURN ZIPLOCK BAGS AND CALORIMETERS TO THE BACK OF THE ROOM.
INSTRUCTOR
: