Lab 7: Observing Two Major Classes of Chemical Reactions
- Page ID
- 514169
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)PURPOSE
- Observe evidence of double displacement reactions, including precipitate formation, gas evolution, and color change.
- Observe evidence of redox reactions, such as metal displacement and the evolution of gases.
- Apply solubility rules to predict precipitate formation and confirm products based on the activity series of metals from experimental observations.
- Write balanced molecular, total ionic, and net ionic equations for double displacement and redox reactions.
INTRODUCTION
Part A: Double Displacement (Metathesis) Reactions
In double displacement reactions, elements in two compounds switch places to form new compounds.
AB + CD → AD + CB (Eq. 1)
Na2SO4 (aq) + BaCl2 (aq) → BaSO4 (s) + 2NaCl (aq) (Eq. 2)
These reactions, also known as metathesis reactions, involve the exchange of ions between compounds in solution, forming new compounds. Typically, a product is a solid, a gas, or a liquid, such as water. When a solid forms, it's called a precipitate, as seen in Equation 2 (Eq.2).
The formation of solids, liquids, gases, or color changes, as well as temperature changes, can indicate the presence of chemical reactions. Exothermic reactions release heat, while endothermic reactions absorb heat, indicating a chemical reaction.
In this experiment, you'll mix various aqueous solutions and observe chemical reactions, using your observations to write balanced chemical equations.
Part B. Redox (Electron Transfer) Reactions
Redox reactions involve the transfer of electrons between chemical species. Oxidation is the loss of electrons, while reduction is the gain of electrons. These reactions are fundamental to many chemical and biological processes.
In this experiment, you will investigate redox reactions involving metals and metal ions in aqueous solutions. The relative reactivity of metals will be determined by observing whether a metal can displace the ions of another metal from the solution. This data can be used to write and balance the molecular and the net equation for each observed reaction and construct an activity series, which ranks metals in order of their reactivity. Indicate NR for no reaction observed
SAFETY PRECAUTIONS
- Always wear safety goggles.
- Hydrochloric acid and sulfuric acid are corrosive. Avoid contact with skin and eyes. In case of contact, flush the affected area with plenty of water and seek medical attention if necessary.
- Sodium hydroxide is caustic. Avoid contact with skin and eyes. In case of contact, flush the affected area with plenty of water and seek medical attention if necessary.
- Metal solutions are toxic. Avoid ingestion and skin contact.
- Dispose of all waste solutions in the designated inorganic waste container.
EQUIPMENT AND CHEMICALS
| Equipment | Solutions | Solutions | Metal samples |
|---|---|---|---|
| 12 or 24-hole Well plates and | 1.0 M Sodium carbonate (Na2CO3) | 3.0 M Sulfuric acid (H2SO4) | Calcium (Ca) |
| small test tubes | 6.0 M Hydrochloric acid (HCl) | 0.1 M Silver nitrate (AgNO3) | Copper (Cu) |
| Dropper bottles | 0.1 M Sodium carbonate (Na2CO3) | 0.1 M Potassium chloride (KCl) | Aluminum (Al) |
| Test tube rack | 0.1 M Copper(II) nitrate (Cu(NO3)2) | 0.1 M Sodium nitrate (NaNO3) | Magnesium (Mg) |
| Labels | 0.1 M Sodium phosphate (Na3PO4) | 0.1 M Copper(II) chloride (CuCl2) | Zinc (Zn) |
| 0.1 M Iron(III) nitrate (Fe(NO3)3) | 0.1 M Magnesium nitrate (Mg(NO3)2) | ||
| 0.1 M Sodium hydroxide (NaOH) | 0.1 M Zinc nitrate (Zn(NO3)2) | ||
| 1.0 M Sodium bicarbonate (NaHCO3) |
EXPERIMENTAL PROCEDURE
Part A: Double Displacement (Metathesis) Reactions
Evidence of a reaction can be observed through the formation of a precipitate, the evolution of a gas, a change in color, a change in pH, the release of heat (exothermicity), or the absorption of heat (endothermic).
1. Label Well plates or test tubes with the appropriate reactant combinations.
2. Using dropper bottles, add approximately 10 drops (or 1 mL in a test tube) of each solution to the corresponding well or test tube as indicated below and record your observation(s) on the report sheet:
1) 1.0 M sodium carbonate + 6.0 M hydrochloric acid
2) 0.1 M sodium carbonate + 0.1 M copper(II) nitrate
3) 0.1 M copper(II) nitrate + 0.1 M sodium phosphate
4) 0.1 M iron (III) nitrate + 0.1 M sodium phosphate
5) 0.1 M iron(III) nitrate + 0.1 M sodium hydroxide
6) 6 M sodium hydroxide + 6 M hydrochloric acid
7) 1.0 M sodium bicarbonate + 6.0 M hydrochloric acid
8) 1.0 M sodium bicarbonate + 3.0 M sulfuric acid
9) 0.1 M silver nitrate + 0.1 M potassium chloride
10) 0.1 M potassium chloride + 0.1 M sodium nitrate
3. Carefully observe each reaction mixture for evidence of a chemical reaction. Record your observations in the data table. Note any precipitate formation, gas evolution, color, or heat changes.
4. For each reaction, write the balanced molecular equation, total ionic equation, and net ionic equation. If no response occurred, indicate "NR."
Part B. Redox (Oxidation-Reduction/Electron Transfer) Reactions
B1: Reactions of Metals with Acid
- Place a small piece of each metal (calcium, copper, aluminum, magnesium, and zinc) into separate wells of a Well plate or small test tubes.
- Add approximately 10 drops (or 1 mL) of 6 M hydrochloric acid to each well or test tube containing a metal.
- Observe the reactions for at least 5 minutes. Record your observations in the data table, noting any gas evolution, color changes, or disappearance of the metal.
- Write balanced molecular and net ionic equations for the observed reactions.
B2: Reactions of Metals with Metal Ions
5. Place a small piece of aluminum in three separate wells or test tubes.
- Add approximately 10 drops (or 1 mL) of each of the following solutions to the wells or test tubes containing aluminum: 0.1 M copper(II) chloride, 0.1 M magnesium nitrate, and 0.1 M zinc nitrate.
- Observe the reactions for at least 5 minutes. Record your observations in the data table, noting any color changes, formation of a precipitate, or changes in the appearance of the metal.
- Repeat steps 1-3 using copper, magnesium, and zinc, adding the corresponding metal ion solutions as indicated in the observation data table.
- Write balanced molecular and net ionic equations for the observed reactions.
CALCULATIONS
Place all waste solutions in the INORGANIC waste container.
Place all metal solids in the waste container labeled METAL SOLIDS.
PRE-LAB QUESTIONS
1. Define or explain the following:
- Double displacement reaction.
- Oxidation and reduction in terms of electron transfer
- Concept of an activity series of metals.
- Difference between a single displacement reaction and a redox reaction
2. Using solubility rules, predict whether a precipitate will form when the following aqueous solutions are mixed. Write the balanced molecular, complete ionic, and net ionic equations, and identify the spectator ions for the reactions below when the aqueous solutions are mixed:
- Aqueous solutions of Lead(II) nitrate and potassium iodide
Molecular Equation:
Complete Ionic Equation:
Spectator Ions:
Net Ionic Equation:
- Aqueous solutions of Sodium chloride and silver nitrate
Molecular Equation:
Complete Ionic Equation:
Spectator Ions:
Net Ionic Equation:
- Aqueous solutions of Copper(II) sulfate and sodium hydroxide
Molecular Equation:
Complete Ionic Equation:
Spectator Ions:
Net Ionic Equation:
Hint: All equations should be balanced
3. Predict whether the following redox reaction will occur:
- Fe(s) + Cu2+ (aq) → Fe2+ (aq) + Cu(s)
(Use the activity series from your textbook, Appendix, or a reliable online source to answer this question.)
4. Identify the oxidizing agent and the reducing agent in the following reaction:
- Zn(s) + 2 H+(aq) → Zn2+(aq) + H2(g)
Chemical Reactions: Metathesis and Redox Report Sheet
Name: Lab Partner(s):
Part A: DOUBLE DISPLACEMENT (METATHESIS)REACTIONS
1) 1.0 M Sodium Carbonate + 6.0 M Hydrochloric Acid (mix in a small test tube)
Observations:
Molecular Equation:
Complete Ionic Equation:
Net Ionic Equation:
2) 0.1 M Sodium Carbonate + 0.1 M Copper(II) Nitrate
Observations:
Molecular Equation:
Complete Ionic Equation:
Net Ionic Equation:
3) 0.1 M Sodium Phosphate + 0.1 M Copper(II) Nitrate
Observations:
Molecular Equation:
Complete Ionic Equation:
Net Ionic Equation:
4) 0.1 M Sodium Phosphate + 0.1 M Iron (III) Nitrate
Observations:
Molecular Equation:
Complete Ionic Equation:
Net Ionic Equation:
5) 0.1 M Sodium Hydroxide+ 0.1 M Iron(III) Nitrate
Observations:
Molecular Equation:
Complete Ionic Equation:
Net Ionic Equation:
6) 6 M Sodium Hydroxide + 6 M Hydrochloric Acid (mix in a small test tube)
Observations:
Molecular Equation:
Complete Ionic Equation:
Net Ionic Equation:
7) 1.0 M Sodium Bicarbonate + 6.0 M Hydrochloric Acid (mix in a small test tube)
Observations:
Molecular Equation:
Complete Ionic Equation:
Net Ionic Equation:
8) 1.0 M Sodium Bicarbonate + 3.0 M Sulfuric Acid (mix in a small test tube)
Observations:
Molecular Equation:
Complete Ionic Equation:
Net Ionic Equation:
9) 0.1 M Potassium Chloride + 0.1 M Silver Nitrate
Observations:
Molecular Equation:
Complete Ionic Equation:
Net Ionic Equation:
10) 0.1 M Potassium Chloride + 0.1 M Sodium Nitrate
Observations:
Molecular Equation:
Complete Ionic Equation:
Net Ionic Equation:
Part B: Redox Reactions
B1: Reactions of Metals and Hydrochloric Acid
1. Calcium + 6.0 M Hydrochloric Acid
Observations:
Molecular Equation:
Net Ionic Equation:
2. Copper + 6.0 M Hydrochloric Acid
Observations:
Molecular Equation:
Net Ionic Equation:
3. Aluminum + 6.0 M Hydrochloric Acid
Observations:
Molecular Equation:
Net Ionic Equation:
4. Magnesium + 6.0 M Hydrochloric Acid
Observations:
Molecular Equation:
Net Ionic Equation:
5. Zinc + 6.0 M Hydrochloric Acid
Observations:
Molecular Equation:
Net Ionic Equation:
B2: Reactions of Metals and Solutions of Metal Ions
1. Aluminum + 0.1 M Copper(II) Chloride
Observations:
Molecular Equation:
Net Ionic Equation:
2. Aluminum + 0.1 M Magnesium Nitrate
Observations:
Molecular Equation:
Net Ionic Equation:
3. Aluminum + 0.1 M Zinc Nitrate
Observations:
Molecular Equation:
Net Ionic Equation:
4. Copper + 0.1 M Magnesium Nitrate
Observations:
Molecular Equation:
Net Ionic Equation:
5. Copper + 0.1 M Zinc Nitrate
Observations:
Molecular Equation:
Net Ionic Equation:
6. Magnesium + 0.1 M Copper(II) Nitrate
Observations:
Molecular Equation:
Net Ionic Equation:
7. Magnesium + 0.1 M Zinc Nitrate
Observations:
Molecular Equation:
Net Ionic Equation:
8. Zinc + 0.1 M Copper(II) Nitrate
Observations:
Molecular Equation:
Net Ionic Equation:
9. Zinc + 0.1 M Magnesium Nitrate
Observations:
Molecular Equation:
Net Ionic Equation:
POST-LAB QUESTIONS
- Explain why the reaction between a strong acid and a strong base is considered a double displacement reaction.
- Which of the reactions you performed could also be classified as acid-base reactions?
- Construct an activity series for the metals tested in this experiment, including hydrogen, based on your observations.
- For the reactions, identify the metal that was oxidized and the metal ion that was reduced.
5. Provide five examples of redox reactions that occur in everyday life.