1
Stockroom Procedures
CHEM 1411
CONTENTS:
Measuring Mass, Length, Volume and Density...............................................................................2
Determining the Concentration of Sugar in a Commercial Beverage .............................................3
Stoichiometry I: Determining the Percent Composition of Ammonium Chloride in a Mixture ....4
Stoichiometry II: Molar Mass .........................................................................................................5
Stoichiometry III: Determining the Percent Composition of Potassium Chlorate in a Mixture .....6
Stoichiometry IV: Titration of Vinegar ..........................................................................................7
Specific Heat Capacity.....................................................................................................................9
Chemical Reactions I: Some Chemical Reactions Involving Oxygen..........................................10
Chemical Reactions II: Reactions of Ions in Solution ..................................................................12
The Gas Laws ................................................................................................................................14
The Gas Laws: Finding the Molar Mass of Oxygen .....................................................................15
Heats of Reaction: Hess’s Law .....................................................................................................16
Titration of Hydrogen Peroxide .....................................................................................................17
Limiting Reactants .........................................................................................................................18
Paper Chromatography ..................................................................................................................19
Empirical Formula by Microanalysis.............................................................................................21
Lewis Structures and the Shapes of Molecules..............................................................................22
2
Measuring Mass, Length, Volume and Density
A. Setting Up.
1. Set up six sets of cylinder samples per lab.
2. Set up six irregularly-shaped unknowns per lab.
3. Each lab will require twelve volumetric pipets and pipet bulbs
B. Cleaning Up.
1. Return the samples to their proper shelf.
2. Clean up around the benches, balances, and fume hoods.
3
Determining the Concentration of Sugar
in a Commercial Beverage
A. Setting Up.
1. 12 50 mL volumetric flasks per lab.
2. Three bottles of sucrose per lab, placed near the balances. Make sure there is adequate
weighing paper by each balance.
3. Plastic transfer pipettes.
4. 12 5 mL volumetric pipettes and pipette bulbs per lab.
5. Fume hood: set up two magnetic stir plates per lab (three if possible), equipped with
magnetic stirbars to degas sodas.
6. Two 2 L sodas for people who didn’t bring any.
B. Cleaning Up.
1. Make sure that all volumetric flasks, volumetric pipettes, and pipette bulbs have been
returned to the equipment cart.
2. Rinse all volumetric flasks and pipettes with distilled water to ensure there is no sugar
remaining on them. (The pipettes can be rinsed all at once by placing them in a large
plastic graduated cylinder and flushing it with water several times.)
3. Clean up any sugar spilled around the balances.
4
Stoichiometry I: Determining the Percent Composition
of Ammonium Chloride, Salt, and Sand in a Mixture
A. Setting Up.
1. Set up Fischer burners in the hoods in pairs, with each pair of burners connected to a gas
jet using a T-connector. Set up a tripod with a wire gauze next to each burner, or a ring
stand with an iron ring if we don’t have enough tripods.
2. Make sure that strikers are available in the lab. Each fume hood should have one striker
in it to make sure that the Fischer burners can be re-lit, if necessary.
3. Wash about 200 6-inch test tubes, and dry them in the oven overnight. Locate stoppers to
fit each test tube.
4. Wash four large glass bottles, and dry them in oven overnight.
5. Fill two or three 600 mL beakers about two-thirds of the way with sand, and another two
or three 600 mL beakers about two-thirds of the way with salt, and place them in the oven
overnight. Place about 100 g of NH4Cl in a large beaker, and crush all of the lumps in it
with a mortar and pestle. Do NOT dry the NH4Cl in the oven!
6. To make unknown mixtures, weigh each of the following mixtures into one of the dried
large bottles:
NH4Cl
NaCl
Sand
A
30 g
70 g
200 g
B
25 g
175 g
100 g
C
20 g
130 g
150 g
D
15 g
200 g
85 g
Be sure to record the actual masses of the sand, salt, and ammonium chloride, and report
that information to your lab supervisor.
7. Tumble each mixture for several hours on the ball mill. (Do not run it overnight.)
8. Fill 50 test tubes with about 5g of mixture A. Do likewise with B, C, and D. Stopper all
test tubes. (The easiest way to do this is to set up a line of test tubes in a test tube rack,
put 5 g in the first one, and fill the others to the same level.)
9. Prepare sample keys and sign-out sheets for the unknowns.
B. Cleaning Up.
1. Return the Fischer burners and T-connectors to their proper place, and put the tripods and
ring stands back against the way.
2. Clean up around the balances.
3. At the end of the week, move the A, B, C, and D samples to a shelf on one of the side
walls in the stockroom for use during the makeup labs and the summer labs.
5
Stoichiometry II: Molar Mass
A. Setting Up.
1. Set up a bottle of sand, salt and sugar for each lab. Leave the bottles on the equipment
cart.
2. Set up a 800 or 1000 mL beaker near each bottle to discard the weighed sand, salt, and
sugar in. Make sure that each beaker is clearly labeled as “Waste Sand,” “Waste Salt,”
and “Waste Sugar.”
revise
B. Cleaning Up.
1. If the waste sand, salt, and sugar look clean, pour them back into the reagent bottles. If
the samples look like they have been mixed up, discard them in the trash.
6
Stoichiometry III: Determining the Percent Composition
of Potassium Chlorate in a Mixture
Suggestion: Have the students work in groups of 4 (2 do heating, 2 do titration, then switch)
A. Setting Up.
1. Wash about 200 6-inch test tubes, and dry them in the oven overnight. Locate stoppers to
fit each test tube.
2. Wash four large glass bottles, and dry them in oven overnight.
3. To make unknown mixtures, weigh each of the following mixtures into one of the dried
large bottles. (Be sure to record the actual masses of the potassium chlorate and sodium
chloride, and report that information to your lab supervisor.) Do NOT dry the NaCl or
KClO3 prior to mixing. Break up all lumps in the KClO3 and NaCl. (Be careful handling
the KClO3: do not grind the KClO3, or strike it roughly with a spatula.)
NaCl
KClO3
A
180 g
120 g
B
150 g
150 g
C
120 g
180 g
D
90 g
210 g
4. Tumble each unknown mixture for several hours on the ball mill. (Do not run it
overnight.)
5. Fill 50 test tubes with about 5g of mixture A. Do likewise with B, C, and D. (The easiest
way to do this is to set up a line of test tubes in a test tube rack, put 5 g in the first one,
and fill the others to the same level.) Stopper all test tubes.
6. Prepare sample keys and sign-out sheets for the unknowns.
B. Cleaning Up.
1. Rinse all test tube that are returned to the stockroom, and allow them to dry before
reshelving them.
2. Clean up around the balances.
3. At the end of the week, move the A, B, C, and D samples to a shelf on one of the side
walls in the stockroom for use during the makeup labs and the summer labs.
7
Stoichiometry IV: Titration of Vinegar
A. Setting Up.
1. Set out 14 burets for each lab. The burets should be rinsed out with deionized water
before placing them on the equipment cart.
2. Set out 2 bottles of phenolphthalein for each lab.
3. Label large bottles of commercially-purchased vinegar as “Vinegar A” and “Vinegar B.”
4. Set up four burets on the side shelves. Two will contain Vinegar A and two will contain
Vinegar B. Label each vinegar buret appropriately.
5. Make sure there is some white paper for students to place underneath their titrations.
6. Prepare a 0.5 M solution of NaOH by dissolving 400 g of NaOH in 20 L of water in a
large carboy. Do NOT add the NaOH all at once, because it will get very hot. Add the
NaOH in small portions to some of the water in a beaker, and when each portion has
dissolved, add it to the carboy. When all of the NaOH has been added, add water to the
carboy to bring the volume up to 20 L.
7. Standardize the NaOH solution according to the directions in section “B.”
B. Standardizing the Sodium Hydroxide Solution.
1. Rinse a buret will first with tap water, and then twice with 5-mL portions of distilled
water. (Make sure that you open the valve so that water flows through the tip as well.)
Rinse the buret twice with 5-mL portions of the NaOH solution (again, making sure to
rinse the tip).
2. Set the buret up in a buret clamp, and fill the buret with the NaOH solution. Allow some
NaOH solution to run out the bottom until there are no air bubbles.
3. Rinse an Erlenmeyer flask thoroughly with distilled water, and dry the outside of the
flask with a paper towel. Weigh the empty flask (6) and add between 1.5 and 2 grams of
solid potassium hydrogen phthalate, KHC8H4O4 (KHP). Reweigh the flask (5), and
determine the mass of the KHP (7).
4. Add approximately 100 mL of deionized water to the flask, and add two drops of
phenolphthalein indicator. Swirl the mixture to dissolve the KHP — be sure that the
KHP has completely dissolved before proceeding with the titration.
5. Record the starting point of the NaOH solution in the buret (2). Place the flask on a sheet
of white paper under the buret and start adding the sodium hydroxide solution to the KHP
solution. As soon as a pink color starts to show in the flask, slow the addition to a
dropwise rate. Continue swirling the flask until the end point is reached.
6. Stop the titration when one drop of NaOH turns the KHP solution to a pink color that
does not disappear with swirling. Record the end point of the titration (1).
7. Repeat the titration using two more samples of KHP. Refill the sodium hydroxide
solution in the buret if the buret is less than half-full.
8. Calculate the molarity of the sodium hydroxide solution.
8
1.
End point of NaOH
2.
Starting point of NaOH
3.
Volume of NaOH used (mL)
4.
Volume of NaOH used (L)
5.
Weight of flask plus sample
6.
Weight of empty flask
7.
Weight of KHC8H4O4
8.
Moles of KHC8H4O4 (204.22 g/mol)
9.
Moles of NaOH added (= moles of KHP)
10.
Molarity of NaOH (moles NaOH / L NaOH)
11.
Average molarity of NaOH
C. Cleaning Up.
1. Rinse vinegar burets with deionized water after every lab period.
2. Store any remaining NaOH in plastic (not glass) bottles, labeled “0.5 M NaOH for
Vinegar Titration.”
3. Rinse all burets with deionized water before returning them to their storage place.
9
Specific Heat Capacity
A. Setting Up.
1. Equipment needed: 2 Styrofoam cups and lids, copper wire stirrers.
2. Metal knowns: set out six or seven large pieces of zinc and copper metal, weighing about
10 g each. If large pieces of metal are not available, we will use large metal shot instead.
3. Metal unknowns: Set up 12 test tubes per lab containing large pieces of metal shot. For
the metals, use lead, aluminum, and nickel.
B. Cleaning Up.
1. Set out all metal samples to dry in the hood overnight, and place them back into their
respective bottles.
10
Chemical Reactions I:
Some Chemical Reactions Involving Oxygen
Equipment for Oxygen Demonstrations
A. Lighting the Match.
1. Strike-on-Box Matches
2. Strike-Anywhere Matches
B. The Bunsen Burner
1. Bunsen Burner without barrel
2. Bunsen Burner with barrel
3. Index cards
4. Evaporating dish (to demonstrate soot)
5. Straight pins to demonstrate matches inside the burner cone
6. Ring stand, O-ring, wire gauze
C. Decomposition of Potassium Chlorate
1. Two ignition tubes containing KClO3 and a small amount of MnO2 on top
2. One-hole stopper with long rubber tubing
3. Large plastic tub (preferably clear or translucent)
4. Collecting bottles (8 with square cover glasses)
D. Reactions in Pure Oxygen — Splint, Cloth, Cigarette, Plastic, and Vaseline
1. Crucible tongs
2. Wood splints
3. Cloth
4. Vaseline
5. Cigarette
E. Iron
1. Steel wool
F. Magnesium
1. Magnesium ribbon
G. Sulfur
1. Deflagration spoon (small spoon at the end of a long handle)
2. Sulfur
3. Two test tubes and stoppers in a test tube rack. Fill one ¼ full of 0.1M HCl, and the other
¼ full of 0.1M NaOH.
4. Acid-base Indicator (Phenol red/Methyl Orange/Phenolphthalein)
H. Red Phosphorus (usually omitted)
1. Deflagration spoon (small spoon at the end of a long handle)
2. Red phosphorus
I. Commercially Available Oxygen
1. Set up a gas cylinder in the room, with a regulator attached, if possible.
2. Balloon (to demonstrate what happens when a valve breaks off a tank).
J. Candle Trick
1. Candle for candle trick (clamp to ring stand)
K. Ammonium Dichromate Volcano
1. Ammonium dichromate, (NH4) 2Cr2O7, aluminum foil (for chromium waste)
11
L. Nitrogen Triiodide
1. NI3 (made by a professor)
2. Feather for end of “chicken stick”
M. Ether Trough
1. Ether, cotton balls, metal trough, wet rags, candle, coarse strainer to hold cotton balls,
candle for end of trough.
Cleaning Up.
1. Clean out ignition tubes from KClO3 decomposition and set them aside to dry.
2. Rinse out collecting bottles, and replace them if necessary.
3. Dump out the test tubes with the 0.1 M HCl and NaOH and replace with fresh reagent.
4. Check to make sure that all supplies are replenished.
12
Chemical Reactions II:
Reactions of Ions in Solution
Note: Concentrate the copper solutions in part B a bit to make the color more obvious
A. Observing Ionic Compounds in Solution.
Display collection of dissolved salts and their colors in solution (x 4)
These solutions need to be in clear, stoppered vials
Sodium chloride, NaCl
Potassium sulfate, K2SO4
Copper(II) chloride, CuCl2
Zinc nitrate, Zn(NO3)2
Cobalt(II) Nitrate, Co(NO3)2
Copper(II) sulfate, CuSO4
Silver nitrate, AgNO3
Nickel(II) nitrate, Ni(NO3)2
Potassium nitrate, KNO3
Iron(III) nitrate, Fe(NO3)3
Copper(II) nitrate, Cu(NO3)2
Chromium(III) nitrate, Cr(NO3)3
Potassium chromate, K2CrO4
Manganese(II) nitrate, Mn(NO3)2
Lead nitrate, Pb(NO3)2
Potassium permanganate, KMnO4
Potassium iodide, KI
Sodium hydrogen sulfite, NaHSO3
Barium chloride, BaCl2
B,C. Precipitation Reactions, Parts I and II.
Solutions in dropper bottles (4 trays per lab) [or is that foolish optimism?]
1. 0.1 M silver nitrate: Add 17 g of AgNO3 / 1L of DI water.
2. 0.1 M barium chloride: Dissolve 20.7 g BaCl2 / 1L of deionized water.
3. 0.1 M cobalt chloride: Dissolve 12.9 g of CoCl2 / 1L of DI water.
4. 0.1 M copper (II) nitrate: Dissolve 12.6 g of Cu(NO3)2 / 1L of DI water.
5. 0.1 M copper (II) chloride: Dissolve 13.4 g of CuCl2 / 1L of DI water.
6. 0.1 M copper (II) sulfate: Dissolve 16.0 g CuSO4 / 1L of DI water.
7. 0.1 M potassium chromate: Dissolve 19.4 g of K2CrO4 / 1L of DI water.
8. 0.1 M potassium sulfate: Dissolve 17.4 g of K2SO4 / 1 L of DI water.
9. 0.1 M potassium iodide: Add 16.68 of KI / 1L of DI water.
10. 0.1 M potassium permanganate: Dissolve 15.8 g of KMnO4 / 1L of DI water.
11. 0.1 M potassium nitrate: Dissolve 10.1 g of KNO3 / 1L of DI water.
12. 0.1 M NaCl: Add 5.84 g of NaCl / 1 L of DI water.
13. 0.1 M sodium bisulfite: Dissolve 10.4g of NaHSO3 / 1L of DI water.
14. 0.1 M lead (II) nitrate: Dissolve 33.1 g of Pb(NO3)2 / 1L of DI water.
15. oxalic acid, solid
16. 6M hydrochloric acid: Add 250 mL of concentrated HCl (12 M) to 250 mL of water for
500 mL of solution. (Caution: Pour acid into water!! Considerable heat is evolved.)
17. 3 M sulfuric acid: Add 83.3 mL of concentrated H2SO4 (18 M) to 250 mL of water for
500 mL of solution. (Caution: Pour acid into water!! Considerable heat is evolved.)
13
D. Neutralization Reactions.
1. 1x 2.5 L bottle of 2.0 M HCl per lab.
2. 1x 2.5 L bottle of 2.0 M NaOH per lab.
3. 1x 500 g bottle of NaHCO3 per lab.
E. Oxidation-Reduction Reactions.
1. Cu metal powder
2. Cu(NO3)2 (solid)
3. Zinc
4. 6 M HCl
5. Wooden splints
6. Calcium metal
7. Copper wire
8. concentrated HCl
9. concentrated HNO3
10. solution of HgCl2
11. Iron nail
12. CuSO4 solution
13. FeCl3 solution
14. Waste beaker for Cu metal and Cu(NO3)2.
15. Waste container for mercury (“A” waste)
14
The Gas Laws
A. Setting Up.
1. Equipment that will be needed for this lab (described for one lab section)
a. 12x Boyle’s law apparatus (Two wooden blocks — one block has a slotted hole to fit
the top of the syringe. This should be labeled “top” using labeling tape. The other
block has a small hole to fit the tip of the syringe and another smaller hole next to it.
This should be labeled “bottom” using labeling tape.)
b. 12x Charles’s law apparatus (rectangular wooden block with a large and small hole).
c. 12x Large plastic syringe with cap
d. 12x gas burets
e. 12x 800 mL beakers
f. Ignition tube (must be clean and dry)
g. 2.5 lb and 5 lb weights (two of each for every four students)
h. 6-7 metal tubs
2. Reagents to be made for this lab:
a. 99% KClO3/1% MnO2. Add 1 g finely powdered MnO2 to 100 g KClO3 in a bottle,
and shake thoroughly to combine.
B. Cleaning Up.
1. Check to make sure that all Boyle’s Law and Charles’ Law apparatus has been returned
to the cart in the box that it came in.
2. Check to make sure that all gas burets and beakers have been returned to the cart.
15
The Gas Laws: Finding the Molar Mass of Oxygen
A. Setting Up.
1. Make sure the are 16 experimental apparatuses (see lab manual) per lab. Set out 16 pinch
clamps per lab, 16 large beakers (800 to 1000 mL), four or five large (1000-2000 mL)
plastic graduated cylinders, and five “Molecular Weight of O2” squirt bottles per lab.
2. Clean around 60 heavy-walled Pyrex test tubes, and dry them in the oven overnight.
3. Make a mixture of 99% KClO3 and 1% MnO2 by combining 99 g of KClO3 and 1 g of O2
in a bottle and shaking it thoroughly. Pulverize any large chunks of KClO3 before the
MnO2 is added. Do not scrape the mixture with a spatula or grind it with a pestle, as this
can cause sparks, and that would not be a good thing.
4. Look up today’s barometric pressure on the barometer and write it on the board.
B. Cleaning Up.
1. At the end of each lab, clean and dry the test tubes for next day’s lab.
16
Heats of Reaction: Hess’s Law
A. Setting Up.
1. Equipment needed: 2 Styrofoam cups and lids, copper wire stirrers.
2. Two bottles of magnesium turnings for each lab.
3. 20L of 2.0 M HCl. Add 3300 mL of concentrated (12 M) HCl to 16700 mL water to
make 20 L of solution in one of the large 20 L carboys. Dispense in labs in 2.5 L bottles.
4. 10L of 2.0 M NaOH. Dissolve 800 grams solid NaOH (in small portions) in 3 L water.
Caution: Cool the solution in ice bath if necessary, and stir it constantly. Place the
solution in a carboys and add water to bring the volume up to 10 L. Dispense in labs in
2.5 L bottles.
B. Cleaning Up.
1. Refill HCl and NaOH bottles at the end of each lab, if necessary.
17
Titration of Hydrogen Peroxide
A. Setting Up.
1. Equipment needed:
a. Burets
b. 5 mL volumetric pipettes and bulbs
c. 50 mL volumetric flasks
d. Plastic weighing dishes
e. Cut pieces of paper (to be used to visualize the titrations)
f. Put out bottles of oxalic acid with small tubes attached containing spatulas by each
scale in the lab. (NOTE: Oxalic acid is a poison — handle with care.)
2. Solutions needed (instructions are provided for one lab section assuming 30 students per
section divided into pairs)
a. 1.0 M H2SO4 (~1.5 L)
 Add 83 mL concentrated H2SO4 (18 M) to 1411 mL water (add acid to water).
 Sulfuric acid solution needs to be placed in a fume hood separate from the
potassium permanganate and labeled 1.0 M H2SO4.
b. 0.020 M KMnO4 (2.5 L)
 Add 7.9 g KMnO4 to 2500 mL water and mix well. It may be easier to add the
water in increments in order to get the KMnO4 to dissolve.
 NOTE: Potassium permanganate is a strong oxidizing agent. Care should be taken
with the reagent as well as with dilute solutions. Dilute solutions can stain
clothing and skin.
 Potassium permanganate needs to be stored in glass bottles and not polyethylene
bottles. Do NOT provide a concentration label for the KMnO4 solution since this
is what is getting standardized. Place the potassium permanganate in a fume hood
separate from sulfuric acid.
B. Cleaning Up.
1. Refill H2SO4 and KMnO4 bottles at the end of each lab, if necessary.
2. Rinse H2O2 burets with deionized water after every lab period.
3. Rinse all burets with deionized water before returning them to their storage place.
18
Limiting Reactants
A. Setting Up.
1. Equipment needed:
a. Burets
b. Burets on the side shelves for dispensing HCl
c. Squirt bottles for the HCl solution
d. Cut pieces of paper (to be used to visualize the titrations)
e. Bottles containing NaOH with a test tube and spatula attached should be kept by each
scale. Leave the lid on these since NaOH is hygroscopic.
2. Solutions needed:
a. 1.0 M HCl (20 L)
 Add 1667 mL concentrated HCl (12 M) to enough water to make 20 L of solution
in a carboy. (Add ~ 10 L water to the carboy before adding the concentrated
HCl.)
 NOTE: It is important to make sure that you add the acid to the water.
b. 1.0 M KOH (20 L)
 Add 1122 g KOH (MM 56.10 g/mol) to enough water to make 20 L of solution.
 NOTE: The process of dissolving NaOH in water is an exothermic reaction, some
heat will be given off. It is important to make sure that the solution is constantly
stirred using a stir bar. Add the KOH in portions to the water, and allow it to cool
before adding more.
c. 1.0 M HNO3 (20 L)
 Add 1250 mL concentrated HNO3 (16 M) to enough water to make 20 L of
solution in a carboy. (Add ~ 10 L water to the carboy before adding the
concentrated HNO3.)
 NOTE: It is important to make sure that you add the acid to the water.
3. The HCl burets for preparation of the solutions are going to need to be constantly filled
throughout the lab period.
B. Cleaning Up.
1. Refill HCl, KOH, and HNO3 bottles at the end of each lab, if necessary.
2. Rinse HCl burets with deionized water after every lab period.
3. Rinse all burets with deionized water before returning them to their storage place.
19
Paper Chromatography
A. Preparation of Indicator Solutions.
1. Preparation of 0.025 M NaOH: Dissolve 1 pellet of NaOH in 100mL H2O.
2. Congo red — Dissolve 0.2 g solid indicator in 200mL H2O
3. Phenol red — Mix 0.2 g solid indicator with 24 mL of 0.025 M NaOH, then dilute to 200
mL with H2O.
4. Bromcresol green — Mix 0.2 g solid indicator with 12 mL of 0.025 M NaOH, then dilute
to 200 mL with H2O.
5. Methyl violet — Dissolve 0.2 g solid indicator in 200 mL H2O.
6. Each lab should have two sets of all of the knowns, which are stored in small capped
vials.
7. Make capillary spotters to put in each vial.
B. Preparation of Chromatography Unknowns.
In a set of vials, mix equal volumes of each of the following indicators to make the unknown
mixture:
1. CR, PR
2. BG, MV
3. CR, BG
4. CR, PR, BG
5. CR, MV
6. CR, PR, BG
7. PR, BG, MV
8. CR, BG
9. PR, MV
10. PR, BG, MV
11. Repeat above sequence
C. Preparation of Chromatography Paper.
1. Cut 200 8x13 cm pieces of paper from large sheets. Draw a line in pencil across one
short end about 2 cm from the edge of the paper. This is bottom of the sheet. Number
from 1-200 in upper right hand corner in pencil. Handle sheets as little as possible to
avoid contamination of sheets.
#
20
2. Draw separate capillary spotters for each of the unknown mixtures. Apply a spot of each
unknown mixture to the appropriately numbered piece of chromatography paper. Let the
spot dry briefly, and then apply a second spot in the same location. To keep the spots as
small as possible, touch the chromatography paper with the spotter quickly and lightly.
3. Store the chromatography papers in a large beaker covered with saran-wrap.
D. Preparation of Developing Solution.
1. Fill a 2.5 L bottle about 2/3 of the way with 1-butanol.
2. Add concentrated ammonium hydroxide (15 M NH3), and shake thoroughly. Continue
adding NH3 until the liquids form two immiscible layers.
3. Each lab should have two bottles of developing solvent in separate hoods. Each lab
should also have an empty 2.5 L bottle labeled “Recovery Bottle,” and fitted with a glass
or plastic funnel.
4. If necessary, the developer can be recycled by saving the butanol layer (top) and adding
more NH3.
E. HCl and NH4OH for Color Changes. (This must be done at the beginning of each lab
period.)
1. In each lab, place approximately 100 mL of 12 M HCl in an 800 or 1000 mL beaker, and
approximately 100 mL of 15 M NH4OH in another. Cover each with a large watch glass.
Place these two beakers in separate hoods, if possible, and in a separate hood from the
developing solvent. (If they are placed in the same hood, keep them separated as much as
possible.)
2. At the end of each day, dispose of the concentrated HCl and NH4OH from each day’s lab
by pouring them (separately!) down the sink (in the hood) with plenty of water.
F. Other equipment. (14 per lab)
1. 800mL beakers
2. Plastic rulers
3. Plastic wrap
4. Rubber bands (heavy)
5. Paper clips
G. Cleaning Up.
1. Pour the reclaimed solvent from the Recovery Bottles back into the Developing Solvent
bottles, and combine the Developing Solvent bottles as necessary. Store them in the
yellow fume cabinet.
2. Rinse all beakers used as developing chambers thoroughly before putting them back on
the shelf.
21
Empirical Formula by Microanalysis (TV Experiment)
A. Setting Up.
1. Bring one TV set into each classroom from room 200A.
2. Make sure each TV is equipped with the “Empirical Formula by Microanalysis” video.
B. Cleaning Up.
1. Return the TV sets to room 200A.
22
Lewis Structures and the Shapes of Molecules