Name:____________________________
AP
Chemistry
Date: __________________
Mr. Grodski III
Experiment 10 • Molar volume of Hydrogen
Introduction:
In this stoichiometry lab we will be investigating the molar volume of hydrogen gas produced
from magnesium and hydrogen chloride. The collection of hydrogen gas will be performed by water
displacement. In this laboratory assignment, the yield of hydrogen gas will be measured by a eudiometer
tube and its volume will be adjusted to eliminate water vapor. The yield of hydrogen will be compared to
the theoretical volume of hydrogen predicted through stoichiometry.
The following unbalanced reaction occurs in the eudiometer tube.
Mg(s) + HCl (aq))
Objectives:
→
magnesium chloride (aq) + hydrogen (g)
1.
2.
3.
Materials:
Mg ribbon, 2000 ml beakers, Eudiometer Tube (gas collector)
HCl (6M) Glass funnel, Thermometer
Cautions:
HCl is diluted yet can still be a skin and eye irritant. Gloves are
available
Procedure:
1. Mass out a piece of magnesium ribbon in the range of 0.06 to 0.08 g.
2. Fill a 2000 ml beaker to the 2/3 full with water.
3. Using a funnel, gloves and goggles pour 20 ml of the 6M HCl acid into the bottom of
the Eudiometer tube. Using a wash bottle, rinse the side of the tube so that there is no
acid remaining at the top the tube.
4. Coil the copper wire around the small Mg ribbon and suspend the Mg inside the tube,
below the calibrations by wrapping the rest of the wire on the outside of the tube.
5. Fill the Eudiometer tube to the top with water (have a partner help).
6. Quickly invert the tube in the water. Use a THUMB or FINGER over the end of the
tube (holding the water and HCl) until the opening is under the water level in the 2000
ml beaker. The reaction will begin when the acid travels down the tube (more dense).
7. Make sure the gas being generated is collected in the tube..
8. The quantity (volume) of gas that was produced can be determined by the calibrations
(ml) on the Eudiometer tube.
9. Measure the distance between the water line and the gas barrier in tube.
10. Calculate the pressure in the tube using manometer theory.
11. Calculate the volume of water vapor collected and subtract this from volume of gas
collected.
12. Adjust the volume of gas of for H2 and adjust to STP molar volume .
13. SHOW ALL WORK!
Name:____________________________
AP
Chemistry
Date: __________________
Mr. Grodski III
Show all work!
1. Mass of Mg metal: _________
2. Volume of H2(g) and H2O(g) gas collected: ____________
3. Barometric Pressure: _____________
4. Temperature of water bath: _____________
5. Moles of Mg used: __________
6. Height of column of water (above water line):_______________
7. Height of column of Hg: _______________
(corrected from water in #6)
8. Partial Pressure of H2 in Eudiometer : ____________
9. Partial Pressure of H2O: ____________
10. Pressure Fraction of H2 in Euidiometer: _____________
11. Fraction of Volume in Eudiometer:_____________
(which is that is pure H2)
12. Volume H2 collected:
______________
(corrected for H2O vapor)
10. Volume of H2 collected: _____________
(corrected to STP)
11. Molar Volume at STP (L/mol) : _____________
12. Percent Error from Avogadro’s molar volume: ______________
13. Percent Yield: ____________