Download Lab #4: Chemical Reactions

Chemistry 108
Chemical Reactions
lab
Name__________________________________
Lab #4: Chemical Reactions
Many chemical reactions can be placed into one of two categories: oxidation-reduction reactions and
double replacement reactions.
Oxidation-reduction reactions are ones in which electrons are transferred from one species to another.
There are four types of oxidation-reduction reactions that we will investigate: synthesis, decomposition,
single replacement, and combustion. There are two types of double replacement reactions that we will
investigate: precipitation reactions and gas forming reactions. In this experiment, these six types of
reactions will be performed. The evidence that reactions are occurring may be (1) a gas is produced (2) a
precipitate (a solid produced when two solutions are mixed) is formed, (3) a color change is observed, (4) a
temperature change is noted, or (5) a flame is produced.
The purpose of this lab is to give the learner hands-on experience in classification, observation, and analysis
of various types of chemical reactions.
PROCEDURE
SAFETY NOTE: WEAR GLOVES AND GOGGLES FOR THE ENTIRE EXPERIMENT.
PART A - SYNTHESIS REACTIONS
Obtain a piece of magnesium ribbon. In order not to damage the bench top, perform the next step of the
experiment over your evaporating dish (an evaporating dish looks like a small, white ceramic bowl and is
located in your locker drawer). Holding one end of the magnesium ribbon with your tongs (tongs are located
in the common locker), ignite the other end in the burner flame. Look for just a moment at the burning
magnesium; do not stare at the magnesium while it is burning because of the intensity of the light. Record
any evidence of chemical change in the Part A Observation Data Table. NOTE: The evidence that
reactions are occurring may be (1) a gas is produced (2) a precipitate (a solid produced when two solutions
are mixed) is formed, (3) a color change is observed, (4) a temperature change is noted, or (5) a flame is
produced. Dispose of the ash from this part of the experiment in the trashcan.
PART B - DECOMPOSITION REACTIONS
Obtain a plastic cup with two platinum wires fused into it and fill the container with the catalyst-containing
water (the water used for this reaction contains an acid catalyst) until the water is about 1cm from the top
of the container. Next, fill an extra-small test tube completely with the catalyst-containing water. Wearing a
disposable glove, cover the top of the test tube with your finger, so that there are no bubbles in it, invert it
into the water in the container, and position it over one of the platinum wires. The extra-small test tubes are
the smallest test tubes in your drawer. Repeat the same procedure with a second extra-small test tube,
positioning it over the second platinum wire. Obtain a 9-volt battery, and connect it to the battery clip on the
wires sticking out of the bottom of the container. Keep the battery connected for two minutes. Record any
evidence of chemical change in the Part B Observation Data Table. The reactant is water; think about
what the identity of the two products could be. If you need more information, review the decomposition
reaction discussion in your prelab.
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Chemistry 108
Chemical Reactions
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IMPORTANT: Pour the solution that is in the plastic cup and test tubes into the largest beaker from your
lab drawer. This beaker will be used for other chemical waste throughout the lab. Keep the waste beaker on
your lab bench. Rinse the cup and test tubes using deionized water from your squirt bottle; pour the rinse
water into the waste beaker. At the end of the experiment, the entire contents of your waste beaker will be
disposed of in the waste container in the fume hood near the lab door.
PART C – SINGLE REPLACEMENT REACTIONS
Part C-1. Place 3 mL of silver nitrate solution in a medium test tube. Add a piece of copper metal and
observe the test tubes for several minutes. Record any evidence of chemical change in the Part C-1
Observation Data Table.
Dispose of the solution and solid from this part of the experiment in your waste beaker. Rinse the test tube
using deionized water from your squirt bottle; pour the rinse water into the waste beaker.
Part C-2. In this single replacement reaction, magnesium replaces the hydrogen in HCl. Place 3 mL of 6M
hydrochloric acid (HCl) into a medium test tube. Add a small piece of magnesium metal (labeled
"magnesium turnings") to the test tube. Record any evidence of chemical change in the Part C-2
Observation Data Table. If a gas is produced, hold your thumb over the mouth of the test tube for about
one minute, light a wooden splint with a Bunsen burner, then remove your thumb and hold the burning splint
to the mouth of the test tube. You will hear a sound when the H2 gas that was produced in reaction C-2
undergoes a second reaction when it reaction with oxygen. Dispose of the solution from this part of the
experiment in your waste beaker. Rinse the test tube using deionized water from your squirt bottle; pour the
rinse water into the waste beaker.
Part C-3. Place 3 mL of deionized water into a medium test tube, which is resting in your test tube rack.
Weigh between 0.02 and 0.05 grams of calcium metal using the weighing paper located near the balances.
Add the calcium to the water in the test tube.
CAUTION: You should be wearing gloves during this entire experiment. Do not touch the calcium
with your bare hands.
Record any evidence of chemical change in the Part C-3 Observation Data Table. Obtain a piece of red
litmus paper. Dip a stirring rod in the solution and touching it to the piece of red litmus paper. Red litmus
paper turning blue indicates that a product of the chemical reaction is an ionic compound where the anion is
hydroxide (OH-). In this reaction, the calcium replaces one of the hydrogens in H2O. Dispose of the
solution and solid from this part of the experiment in your waste beaker. Rinse the test tube using deionized
water from your squirt bottle; pour the rinse water into the waste beaker.
PART D – COMBUSTION REACTION
Remove a Bunsen burner from the common locker, connect it to the gas outlet, and light it in the manner that
was demonstrated by your instructor. The major component of the natural gas is methane (CH4). Remove
any flammable material from your lab bench. Holding the burner by its base, turn the burner over and have
the flame come in contact with the lab bench for 2 or 3 seconds. Place the burner back on the lab bench and
turn it off. Record your observations of the product seen on the lab bench in the Part D Observation
Data Table.
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PARTS E and F : DOUBLE REPLACEMENT REACTIONS
PART E – PRECIPITATION REACTIONS
Place about 2 mL of mercury(II) nitrate solution into a clean, medium test tube, and place about 2 mL of
aluminum nitrate solution into a second clean, medium test tube. Add about 2 mL of potassium iodide
solution to both of the test tubes. Record any evidence of chemical change in the Part E-1 and E-2
Observation Data Tables. If a precipitate forms, write the balanced equations in the Part E–1 or Part E–2
sections of the Reaction Table. If no reactions occurred, write NR (NR means No Reaction). Place both
solutions in the waste beaker on your lab bench.
Place about 2 mL of mercury(II) nitrate solution into a clean, medium test tube, and place about 2 mL of
aluminum nitrate solution into a second clean, medium test tube. Add about 2 mL of sodium phosphate
solution to both. Record any evidence of chemical change in the Part E-3 and E-4 Observation Data
Tables. If a precipitate forms, write the balanced equations in the Part E–3 or Part E–4 sections of the
Reaction Table. If no reactions occurred, write NR. Place both solutions in a waste beaker on your lab bench.
Dispose of the solutions and any solids from this part of the experiment in your waste beaker
PART F – GAS FORMING REACTIONS
Place about 3.0 mL of sodium bicarbonate (NaHCO3) solution in the bottom of a large test tube. Add a few
drops of 6M HCl solution. Record any evidence of chemical change in the Part F Observation Data
Table. The contents of the tube can be washed down the sink with water.
Dispose of the solution and any solid from this part of the experiment in your waste beaker. Rinse the test
tube using deionized water from your squirt bottle; pour the rinse water into the waste beaker.
Empty the entire contents of your waste beaker in the waste container in the fume hood near the lab door.
Rinse the waste beaker using deionized water from your squirt bottle; pour the rinse water into the waste
container.
COMPLETE THE REACTION TABLE ON THE LAST PAGE OF THE HANDOUT.
Write the balanced equations for each of these reactions in the Reaction Table. Remember to write the
phase [(g),(l),(s), or (aq)] after each reactant or product for all of the chemical equations in your
Reaction Table.
THE REACTION TABLE CAN BE DONE AT HOME. TURN THE LAB AND PRELAB IN AT THE
BEGINNING OF THE NEXT LAB PERIOD.
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DATA TABLE
PART A OBSERVATIONS
EVIDENCE OF REACTION
Magnesium + Oxygen
PART B OBSERVATIONS
EVIDENCE OF REACTION
Water
PART C-1 OBSERVATIONS
EVIDENCE OF REACTION
Silver Nitrate + Copper
PART C-2 OBSERVATIONS
EVIDENCE OF REACTION
Hydrochloric Acid + Magnesium
PART C-3 OBSERVATIONS
EVIDENCE OF REACTION
Water + Calcium
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Chemistry 108
Chemical Reactions
PART D OBSERVATIONS
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EVIDENCE OF REACTION
Methane + Oxygen
PART E-1 OBSERVATIONS
EVIDENCE OF REACTION
Mercury (II) Nitrate + Potassium Iodide
PART E-2 OBSERVATIONS
EVIDENCE OF REACTION
Aluminum Nitrate + Potassium Iodide
PART E-3 OBSERVATIONS
EVIDENCE OF REACTION
Mercury (II) Nitrate + Sodium Phosphate
PART E-4 OBSERVATIONS
EVIDENCE OF REACTION
Aluminum Nitrate + Sodium Phosphate
PART F OBSERVATIONS
EVIDENCE OF REACTION
Hydrochloric Acid (HCl) + Sodium Bicarbonate
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REACTION TABLE:
Write a balanced chemical equation for each of these reactions. Remember to write the phase
[(g),(l),(s), or (aq)] after each reactant and product.
PART A
Hint: One of the reactants is O2, and the product is an ionic compound.
PART B
Note: The only reactant is water; the acid is just a catalyst and not a reactant or product. Since the only
reactant is water, think about what the identity of the two products are for a decomposition reaction.
PART C-1
Hints: (1) See the single replacement discussion and examples in your pre-lab, and (2) the copper is being
oxidized to Cu2+.
PART C-2
PART C-3
In this reaction, the calcium replaces one of the hydrogens in H2O.
PART D
PART E-1 Mercury (II) Nitrate + Potassium Iodide
PART E-2 Aluminum Nitrate + Potassium Iodide
PART E-3 Mercury (II) Nitrate + Sodium Phosphate
PART E-4 Aluminum Nitrate + Sodium Phosphate
PART F HCl + Sodium Bicarbonate
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