Transcript Lab 9 • Today you will set up your equipment and run your experiment prior to the pre-lab lecture. • After you.

Lab 9
• Today you will set up your equipment and run your experiment
prior to the pre-lab lecture.
• After you are finished, return to your seats.
• Here’s how to proceed:
• Weigh out a Mg strip
• Roll into a ball
• Insert into alligator clip
• Carefully add 10 mL of 6M
HCl to the eudiometer tube.
• Fill the tube carefully with
distilled water.
• Place the stopper in the tube
and eliminate all air
bubbles.
• With your finger over the
hole in the stopper, invert
the tube and place in 100
mL dH2O.
• Clamp the tube to a buret
clamp.
• The stopper should be
4 mm from the bottom.
• Record the time.
• Record the volume of H2
gas from your
eudiometer tube after 1
hour.
• Go ahead…
The molar volume of all gases at STP is 22.414 L/mol.
In this experiment, we will be collecting H2 gas by displacement of
water to determine the molar volume of H2 gas experimentally, i.e.
confirm that it is 22.433 L/mol. Note the slight deviation from ideal
behavior.
Physical properties of gases can be related through
mathematical equations, known as laws:
• For Single Gases k
• Boyle’s Law:
V=
P
; at constant T and n
• Charles’ Law:
V = bT; at constant P & n
• Avogadro’s Law: V = an; at constant T and P
• Ideal Gas Law:
PV = nRT
• For Mixed Gases • Dalton’s Law:
PT = P1 + P2 + P3 …
The net ionic equation for this redox reaction is:
2H+(aq) + Mg(s)  Mg2+(aq) + H2(g)
reduced oxidized
•
•
•
•
Accepted Molar Volume is 22.433 L/mol
Atmospheric Pressure can be obtained from the barometer
Vapor Pressure of Water in mmHg is obtained from Table 9.1
Water Bath Temperature in degrees Celsius is obtained using
the digital thermometer
• The pressure difference in mm H2O is measured with a meter
stick.
• Mass of Magnesium is obtained from the balance
• Partial Pressure of H2 gas in mmHg from Dalton’s law.
• Volume of H2 gas is obtained from your Eudiometer tube.
• Volume of H2 gas at STP is obtained from:
Example:
PH2  VH2
TH2O
PSTP  V2
=
TSTP
(730.0mmHg)(33.18mL)
(760.0mmHg)(V2 )
=
293.6K
273.15K
• Theoretical moles of H2 are obtained from:
(mass Mg)(1mol H2 )
moles H2 =
(fw Mg)(1mol Mg)
• Molar Volume of H2 gas is obtained from:
(vol of H2 at STP, L)
molar VolH2 =
(theoretical moles H2 )
• Reagents:
• Hydrochloric Acid
• Magnesium Metal
• Eye Contact:
• irreversible damage, severe burns, painful sensitization to light
• Skin Contact:
• Burns, rash, and ulceration
• Ingestion:
• digestive tract burns, circulatory system failure, abdominal pain, diarrhea,
vomiting, and death
• Inhalation:
• sore throat, coughing, shortness of breath, lung edema, burns, erosion of
teeth, damaged mucosa, chest pain, fever, and leukocytosis
• Acidic solutions / waste need to be disposed in the acid
waste container in the fume hood.
• Lab 10 is next.