Name Date: Lab Partners / 33 pts Lab: Gas Stoichiometry Visual

Name
(1 pt)
Lab Partners
Date:
(1 pt)
(1 pt)
/ 33 pts
Lab: Gas Stoichiometry
Visual Observations: What changes occurred over the course of the experiment? (2 pts)
Data Table
o
(3 pts – masses recorded to nearest 0.01 g, volumes to nearest 10 mLs, temperatures to nearest 0.1 C)
Trial 1
1
Mass of CuCO3  Cu(OH)2
2
Total volume of collection bottle
3
mLs of water remaining in bottle after collecting gas
4
mLs of gas in bottle (1 pt)
5
L of gas in bottle (1 pt)
6
Water temperature in C (water in trough)
7
Water temperature in K (CO2 gas temperature is the same as this
8
Barometric Pressure in inches of Hg (from board)
9
Barometric Pressure in kPa (1 pt)
10
Vapor Pressure of Water (use nearest whole oC in table below)
(recall that ‘’ means ‘+’)
o
water temperature) (1 pt)
12
Barometric Pressure (corrected for pressure of water
vapor) in kPa (2 pts)
L of CO2 expected from the stoichiometry equation
13
% error (using the result of #12 as true value)
11
Trial 2
(5 pts)
(1 pt for doing calculation correctly, 3 pts for accuracy)
Temperature
o
( C)
15
16
17
18
19
20
21
22
Vapor Pressure of Water Vapor
Pressure
Temperature
o
(kPa)
( C)
1.71
23
1.81
24
1.93
25
2.06
26
2.20
27
2.33
28
2.48
29
2.64
30
Pressure
(kPa)
2.80
2.99
3.16
3.36
3.59
3.77
4.00
4.24
Calculations – SHOW your calculations for both trials in the space below!
 In step 12: grams of CuCO3  Cu(OH)2 x _1_ x RTwater = L of CO2 expected at room conditions
molar mass
1
Pcorrected
Conclusion Questions
1. How many grams of CuCO3  Cu(OH)2 would be needed to produce 22.4 L of CO2 at STP? (2 pts)
2. What are 4 possible sources of error in this experiment? Identify four sources of error (4 pts), then calculate the
magnitude of error for each source you identified (4 more pts). Be sure to label your calculations; don’t just write
down numbers.
(Note: sources of error are quantities that were measured. You can’t cite “human error” because you didn’t
measure any “humans”! Also, things like “doing calculations incorrectly” or “measuring wrong” are NOT errors;
they are your mistakes – there’s a big difference between measurement errors and mistakes.)




Which source of error contributed the most to your % error?
Magnitude of error = (readability / measurement) x 100. For example, if you were using a small graduated cylinder to
measure a volume, it would be readable to 0.1 mLs. If your measurement was 8.5 mLs, the magnitude of error would be
(0.1 mLs / 8.5 mLs) x 100 = 1%
Procedure for Gas Stoichiometry Lab
Record all masses to nearest 0.01 g, all temperatures to nearest 0.1oC, and volumes to nearest 10 mLs.
Clean up any spills of the basic copper(II) carbonate immediately with a moist paper towel. Do not allow this chemical to sit on the benchtop or the
balance!
1. Obtain a large test tube, called an “ignition tube”.
2. Place the ignition tube on a lab balance, tare it, then add between 2.00 g and 2.30 g of CuCO 3  Cu(OH)2. Record the mass of the basic copper(II)
carbonate.
3. Clamp the ignition tube onto a lab stand so that the clamp holds the tube just behind the lip, and the tube is just slightly above horizontal.
4. Insert a stopper attached to a rubber hose into the mouth of the ignition tube with a slight twisting motion so it seals tightly.
5. Obtain a 500 mL gas collection bottle. Fill the bottle with tap water. Place a glass square over the mouth of the bottle. Pour the water into a 1000
mL graduated cylinder and record the volume of the bottle. Refill the bottle with water and place the glass square back over the mouth of the
bottle.
6. Fill either your lab sink or a plastic bucket about ½ full with tap water. Invert the gas collection bottle and place it into the water. Remove the glass
square and set it aside.
7. Thread the hose from the ignition tube up into the mouth of the gas collection bottle.
8. Begin heating the ignition tube with a Bunsen burner. Move the flame back and forth along the length of the tube to evenly decompose the basic
copper(II) carbonate. Gas will begin to collect in the bottle.
9. When all of the basic copper(II) carbonate has turned from green to black and no more gas is bubbling into the gas collection bottle, carefully remove
the hose from the gas collection bottle. Warning! Do not remove the flame from under the ignition tube until you’ve first removed the hose
from the bottle. Otherwise, cold water may be sucked back into the hot tube causing it to shatter violently.
10. Place the glass square back over the mouth of the gas collection bottle. Remove the bottle from the water, holding the glass square in place.
11. Take the temperature of the water in the bottle. Measure the volume of the water remaining in the bottle.
12. Perform a 2nd trial. Clean up all equipment. Do not put anything away dirty, including the ignition tube.