Cold Heat:

• Mix 10ml of water and 10ml of ethanol.
• Fold a piece of paper into a small square and soak it in the water-alcohol mixture.
• Turn off the room lights to make the flame more visible.
• Use tongs to hold the paper and ignite it with a match.
• After the flame burns out, unfold the paper and examine it.

Molecular motion:

• Before class do the following:
  • Place a small amount of 12M HCl in a wide mouth bottle and seal the top.
  • Do the same with a similar amount of concentrated NH₃.
  • Label both bottles.

• For the demonstration, do the following:
  • Place both bottles in a fume hood (do not turn on the hood) about a foot apart.
  • Open both bottles, close the door of the hood, and observe.

  Results:

• When the vapors come together, NH₄Cl "smoke" will form in the reaction:
  NH_{3 (g)} + HCl _(g) NH₄Cl _(cr)

Equilibrium in Gases:

• Place 10 ml of of concentrated nitric acid in a flask.
• Drop a penny in the flask.
• The deep red gas is NO₂. When the gas has filled the flask, "pour" two test tubes of the gas and stopper them.
• Stop the rection in the flask by filling the flask with water.
• Place one tube in a beaker of boiling water. The color gets deep brown.
• Place the other tube in an ice bath. The gas becomes almost colorless.
• Remove both tubes and bring them to room temperature. The original color returns to both tubes.
• The equation for the gas production is: Cu_(s) + 4H⁺_(aq) + 2 NO₃^-_(aq) Cu⁺²_(aq) + 2NO_2(g) + 2H₂O_(l)
• The equilibrium gases are:
  2NO_{2(g) RED} N₂O_{4(g) COLORLESS}

• Clean and dry two 100 ml graduated cylinders.
• Push a small, moist piece of blue litmus paper to the bottom of the cylinder.
• Lay the cylinder on its side, making sure it is level.
• Dip a small piece of cottom in concentrated HCl and place it just inside the mouth of the cylinder.
• Immediately seal the mouth of the cylinder with plastic wrap and begin timing the diffusion.
• When the HCl gas reaches the bottom of the cylinder, the litmus paper will turn red.
• Record the time required for the gas to travel the length of the cylinder.
• Repeat the procedure with ammonium hydroxide and red litmus paper. Graham's law states that the rate of diffusion of two gases is inversely proportional to the square roots of their molecular masses.
  1. Determine the rate by dividing the distance the gas traveled, in centimetes, by time, in seconds.
  2. Determine the ratio by dividing the rate of diffusion of HCl gas by the rate of diffusion of NH₃ gas.
  3. The theoretical ratio is:
     (NH₃ diffusion rate) / (HCl diffusion rate) = square root of [(HCl molecular mass) / (NH₃ molecular mass)] = 1.46

Carbon Catalyst:

• Hold a sugar cube on the end of a toothpick and try to burn it with a match.
• The melting point of sucrose is 185 ^oC. The sugar cube melts before it burns.
• Dip another cube in very fine powdered animal charcoal (carbon).
• When a match is brought to this cube, it burns easily.
• The carbon acts as a catalyst in the combustion of sugar.

• Place a LARGE graduated cylinder on a tray.
• Pour about 50 ml of 30% hydrogen peroxide into the cylinder.
• Add a squirt of dishwashing detergent.
• Finally add about one-fourth of a spoonful of solid KI.
• The rapid production of oxygen causes boam to fill, and probably overflow the cylinder.
• The two-step decomposition of H₂O₂ is:
  1. H₂O_2aq + I ^-_aq H₂O_l + OI ^-_aq
  2. H₂O_2aq + OI ^-_aq H₂O_l + O_2g + I ^-_aq
• Reaction "a" is the rate-determing reaction.

A Reversible Reaction:

• Dissolve 14 grams of NaOH in 500ml of water in a 1000ml flask.
• Add 14 grams of dextrose and a few drops of methylene blue indicator to the flask.
• Stopper the flask tightly and shake vigorously until the solution is blue in color.
  This caustic solution damages skin and eyes. Be careful that the flask does not leak.
• Allow the solution to sit and observe the color change as the reaction reverses.
• Will shaking the flask again cause the color to change back?

Does Temperature Affect Equilibrium?

• Dissolve 6 g of cobalt chloride in 250 ml of ethanol.
• Add water drop by drop while stirring until pink.
• Add 12M hydrochloric acid drop by drop while stirring until purple.
• Place 80 ml of this solution in each of 3 graduated cylinders.
• Place one in ice, one in hot water, and leave one at room temperature.
• Observe the color after 10 minutes.
• The reaction: CoCl₄ ^-2_(aq) (BLUE) + 6H₂O_(l) Co(H₂O)₆ ⁺² (PINK) + 4Cl ^-2_(aq)

Arrhenius Acids & Bases:

• Prepare 100 cm³ of 0.1M H₂SO₄ by adding 0.6 cm³ of 18M H₂SO₄ in 99.4 cm³ of distilled water.
• Add 10 cm³ of the 0.1M H₂SO₄ solution to 90 cm³ of distilled water to prepare 100 cm³ of 0.01M H₂SO₄.
• Prepare 100 cm³ of 0.01M Ba(OH)₂ by adding 0.32g to 100 cm³ of water.
• Add the 0.01M H₂SO₄ solution to the beaker of a conductivity apparatus.
• Place the beaker on a magnetic stirrer, add the stirring rod, place the electrodes of the conductivity apparatus in the beaker, and turn on the magnetic stirrer. Observe.
• While stirring, add the 0.01M Ba(OH)₂ solution to the beaker drop-by-drop. Observe the formation of the salt, BaSO₄ and the conductivity change indicated by the light bulb.

• Explain the observations using the Arrhenius theory.

Amphoteric Neutralization:

• Dissolve 0.5g of Al₂(SO₄)₃ in 60 cm³ of distilled water.
• Place a few cm³ of this solution to a petri dish on an overhead projector. Add a few drops of universal indicator. Note the color of the solution.
• Add 3M (1.8g NaOH in 15 cm³ water) sodium hydroxide solution drop by drop to the dish while stirring until a clear, violet solution is produced. Note the color of the solution.
• Add 3M (5 cm³ of 12M HCl in 15 cm³ water) hydrochloric acid solution drop by drop to the dish while stirring until a clear, red solution results. Note the color of the solution.

  The entire range of the universal indicator will appear as the acids and base react with the aluminum sulfate in the following reactions:

  • Dissolving Al₂(SO₄)₃ in water produces an acidic solution through this process:
    Al⁺³ + 6H₂O [Al(H₂O)₆]⁺³
    [Al(H₂O)₆]⁺³ + H₂O [Al(H₂O)₅OH]⁺² + H₃O⁺¹
  • A gelatinous precipitate forms when a base is added.
    Al⁺³ + 3OH ^- Al(OH)₃
  • In excess base, the aluminum complex ion forms.
    Al⁺³ + 4OH ^- [Al(OH)₄] ^-
  • In acid, the Al(OH)₃ dissolves.
    Al(OH)₃ + 3H⁺ Al⁺³ + 3H₂O

Preparation for solutions with pH from 1 to 13:

• Standard Acidic Solutions:
  • Mix 2.1 cm³ of 12M HCl with 248 cm³ of distilled water to make a 0.1M HCl solution with a pH of 1.
  • Add 5 cm³ of the 0.1M HCl to 45 cm³ of distilled water to make a solution with a pH of 2.
  • Repeat using 5 cm³ of each previously diluted HCl solution and 45 cm³ of distilled water to make solutions with pH 3-6.
• Standard Neutral Solution:
  • Boiled distilled water will have a pH of 7.
• Standard Basic Solutions:
  • Add 1.05 g of NaOH to 249 cm³ of distilled water to make a 0.1M NaOH solution with a pH of 13.
  • Add 5 cm³ of the 0.1M NaOH to 45 cm³ of distilled water to make a solution with a pH of 12.
  • Repeat using 5 cm³ of each previously diluted NaOH solution and 45 cm³ of distilled water to make solutions with pH 11-8.

Formation of Metals by Displacement:

• Solutions:
  • 2% AgNO₃ - Dissolve 4 g in 200 ml of distilled water.
  • 5% SnCl₂ - Dissolve 10 g in 200 ml of water.
  • 5% Pb(CH₃COO)₂ - Dissolve 10 g in 200 ml of water.
• Place a heavy, coiled copper wire in the AgNO₃ solution.
• Place an iron nail, or coil of heavy iron wire in the SnCl₂ solution.
• Place a strip of zinc in the lead acetate solution.
• Each of these displacements becomes apparent in a few minutes, but complete crystal formation may take several hours.
• The reactions involved:
  • Ag⁺²_(aq) + 2NO₃^-_(aq) + Cu_(s) Ag_(s) + Cu⁺²_(aq) + 2NO₃^-_(aq)
  • Sn⁺²_(aq) + 2Cl ^-_(aq) + Fe_(s) Sn_(s) + Fe⁺²_(aq) + 2Cl ^-_(aq)
  • Pb⁺²_(aq) + (CH₃COO ^-)_2(aq) + Zn_(s) Pb_(s) + Zn⁺²_(aq) + (OCH₃CO ^-)_2(aq)

Oxidation of glycerin by permanganate:

• Place a small pile of granular potassium permanganate, a tablespoonful, in an evaporating dish.
• Pour about 10 ml of glycerin, glycerol, on top of the pile.
• In 10 to 20 seconds, rapid oxidation will occur!!
• The reaction is:
  14KMnO_{4 (g)} + 4C₃H₅(OH)_{3 (l)} 7 K₂CO_{3 (s)} + 7Mn₂O_{3 (s)} + 5CO_{2 (g)} + 16H₂O _(l)

• Is this a Redox reaction?

Electrolysis:

• Disolve 2g KI in 50 cm³ of distilled water.
• Place a small amount of the solution in a small beaker and add a couple of drops of phenolphthalein.
• Connect two pieces of copper wire (electrodes) to a 9-volt battery.
• Dip the electrodes into the KI soultion and observe.

  - Bubbling occurs at the cathode as H₂ .
  - The solution around the cathode turns pink as OH ^- is produced.
  - The solution around the anode turns brown as I₂ is produced and combines with I ^- to form I₃ ^-, which is brown.
  - The reaction is: 2H₂O + 3I ^- H₂ + I₃^- + 2OH ^-

Electrochemical Potential:

• Insert a piece of copper metal and a piece of zinc metal into a potato.
• Connect the two pieces of metal to a current detector.
• "What causes the needle to move?"

An Endothermic Reaction of Two Solids:

• Place 20 g of barium hydroxide in a small beaker.
• Add 20 g of ammonium thiocyanate.
• Stir with a wooden splint.
• This reaction will freeze water is the beaker is placed in a small pool.

• Prepare a 0.5M solution of Na₂SO₃ by adding 6.3 g to 100 ml of water.
• Pour 50 ml of bleach into a beaker and record the temperature.
• Add 50 ml of the sodium sulfite solution.
• Note the increase in temperature is approximately 20 C^o.

Spontaneous Combustion of Acetylene by Chlorine Gas:

• Place 25 ml of bleach (sodium hypochlorite) in a 500 ml beaker.
• Add 10 ml of 6M HCl.
• Cover the beaker with a piece of cardboard and watch the gas produced.
• After a couple of minutes, quickly drop a few small lumps of calcium carbide into the beaker and recover.
• The bubbles of acetylene will immediately burst into flame.
• The reactions involved:
  • Chlorine gas: ClO ^-_(aq) + Cl ^-_(aq) + 2H⁺_(aq) Cl_2(g) + H₂O
  • Acetylene gas: CaC_2(s) + 2H₂O_(l) C₂H₂ + Ca⁺²_(aq) + 2OH ^-_(aq)
  • The tendency of Cl_2(g) to remove hydrogen is so great that it reacts spontaneously with C₂H_2(g) to produce the highly exothermic reaction: C₂H_2(g) + Cl_2(g) 2HCl + 2C + heat

Synthesis of Rayon:

• Prepare a solution of tetraamminecopper (II) hydroxide.
  1. Fill a 500 ml beaker about one-fourth full of water.
  2. Add copper sulfate and stir until the solution is saturated.
  3. While stirring, add concentrated ammonium hydroxide drop by drop until a light blue color and a precipitate form.
  4. If the solution becomes dark blue, you must start over.
• Tear a piece of filter paper into small pieces and place in a small beaker.
• Add about 25 ml of the prepared solution to the beaker.
• Stir the solution until the filter paper completely dissolves. Add more solution, if necessary.
• Fill a dropper or small syringe with the dissolved paper.
• Using a gentle, even pressure, squirt the solution into a beaker of 2M sulfuric acid (dilute 112 ml of concentrated reagent to one liter with water).
• When the white rayon forms, it can be removed, washed, and dried.
• The reaction:
  1. This is the cuprammonium process for making rayon.
  2. Cellulose in the filter paper is dissolved by tetraamminecopper (II) hydroxide, Cu(NH₃)₄(OH)₂.
  3. Upon acidification, cellulose is regenerated into hardened filaments of rayon.

Synthetic Rubber:

• Prepare a solution of sodium polysulfide:
  1. Add 10 g of NaOH to 150 ml of water and boil until it dissolves (not long).
  2. Stir and slowly add 20 g of sulfur.
  3. Continue stirring for about 15 minutes, or until the solution changes from light yellow to dark brown.
  4. After the solution cools, pour off the dark brown sodium polysulfide.
• Place the polysulfide solution in a large beaker and heat to 65-70^oC.
• Stir in 1 g of Mg(OH)₂ until it all dissolves.
• Slowly add 25-30 ml of ethylene chloride. This reaction is exothermic! Do not let the temperature exceed 80^oC! Stir the solution for about 15 minutes. The solution will change from dark brown to cloudy light brown.
• Remove the beaker from the heat and allow to cool slowly to room temperature.
• The polysulfide rubber should settle to the bottom of the beaker. Pour off the liquid and rinse the rubber several times with water.
• If the material doesn't coagulate into one large mass, add 10 drops of dilute HCl, stir, and rinse again.
• Remove the rubber, squeeze the water out, form it into a ball and see if it bounces.

Chain Reaction:

• Tape 8 to 10 books of paper matches in a line on a metal rod with the heads pointing outward.
• Use a ring stand to clamp the metal rod upright.
• Light the bottom match. The others will ignite in turn.

• Each match represents an atom that fissions, emitting one neutron, causing the next atom to fission.
• Energy is released as an unstable, fissionable element changes into a more stable element.