6.2: Lab - Chemical Reactions and Equations
- Page ID
- 438410
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Equipment and Materials
Prepare 12 sets of equipment and 6 set of materials for 24 students per class section. Include a few more for backup if needed. Each set should include
Equipment
- Crucible tongs
- Bunsen Burner
- Test tubes
- Wood splint
- Transfer pipet
- Graduated cylinder
- lighter
Materials (6 trays contain each material should be prepared)
- Metal pieces (copper wire, magnesium ribbon, zinc metal, magnesium metal, copper metal)
- Copper (II) carbonate solid
- Sodium carbonate solid
- ~ 1.0 M hydrochloric acid (\(\ce{HCl}\)) solution (~ 90 mL concentrated \(\ce{HCl}\) into 1L water)
- ~ 1.0 M copper (II) sulfate solution ( ~ 250 g of copper (II) sulfate pentahydrate into 1 L water)
- ~ 0.1 M lead (II) nitrate solution ( ~ 33 g of lead (II) nitrate into 1 L water)
- ~ 0.1 M Potassium iodide (\(\ce{KI}\)) solution ( ~ 16.6 g potassium iodide into 1 L water)
- Unknowns in regular plastic bottles
- Unknown A: Lead Nitrate
- Unknown B: Strong Acid
- Unknown C: Distilled water
- Observe chemical reactions.
- Differentiate different types of chemical reactions.
- Write balanced equations representing chemical reactions.
- Use chemical reactions for metabolism diagnostics.
Laboratory Skills
- Practice recording chemical reactions.
- Practice reading measurements in graduated cylinder.
- Practice using chemical reactions to solve clinical problems.
Equipment and Materials
- Crucible tongs
- Bunsen Burner
- Test tubes
- Wood splint
- Transfer pipet
- Graduated cylinder
- Metal pieces (copper wire, magnesium ribbon, zinc metal, magnesium metal, copper metal)
- Copper (II) carbonate solid
- 1.0 M hydrochloric acid (\(\ce{HCl}\)) solution
- 1.0 M copper (II) sulfate solution
- 0.1 M lead (II) nitrate solution
- 0.1 M potassium iodide (\(\ce{KI}\)) solution
- Sodium carbonate solid
Safety and Hazard Information
It is recommended to wear gloves when handling chemicals in this lab.
Safety goggles should be worn at all times.
All waste will go into the specified waste container.
Background Information
Chemical reactions are ubiquitous and used to understand and explain how our world works. Changes in color, temperature, gas evolution and formation of a precipitate are used to determine whether a chemical reaction has taken place. Like chemical changes, chemical reactions usually lead to the formation of new matter. There are many examples of chemical reactions that occur in medicine and health. For example, ibuprofen is made in pharmaceutical companies using a chemical reaction. An antacid is a substance which neutralizes stomach acidity and is used to relieve heartburn, indigestion or an upset stomach. (https://en.Wikipedia.org/wiki/Antacid)
Furthermore, the identification of body metabolites for diagnostic purposes in a clinical setting or predicting the identity of an unknown specimen usually depends on a chemical reaction. Barium sulfate (\(\ce{BaSO4}\)) is used to help doctors examine the esophagus (tube that connects the mouth and stomach), stomach, and intestine using x-rays or computed tomography (CAT scan, CT scan; a type of body scan that uses a computer to put together x-ray images to create cross-sectional or three dimensional pictures of the inside of the body). Barium sulfate (\(\ce{BaSO4}\)) is in a class of medications called radiopaque contrast media. It works by coating the esophagus, stomach, or intestines with a material that is not absorbed into the body so that diseased or damaged areas can be clearly seen by x-ray examination or CT scan. (https://medlineplus.gov/druginfo/meds/a606010.html)
The interest many students have in science careers usually stems from excitement and entertainment from chemical demonstrations. Chemical changes or reactions are usually depicted by a chemical equation. There are many kinds of chemical reactions and several ways to classify them. One useful method classifies reactions into four major types:
- Combination or synthesis
- Decomposition
- Single replacement
- Double replacement
These four major reaction types are summarized in Table \(\PageIndex{1}\) below. Note that not all reactions can be put into one of these categories.
Table \(\PageIndex{1}\): Types of reactions
| Reaction Types | Chemical Equation | Description |
|---|---|---|
| Combination |
\(A + B \rightarrow AB\) Ex: \( 2\ce{H2} (g) + \ce{O2} (g) \rightarrow 2\ce{H2O} (l)\) |
Two or more substances (elements or compounds) combine to form a more complex substance |
| Decomposition |
\(AB \rightarrow A + B\) Ex. \(2\ce{H2O} (l) \rightarrow 2\ce{H2} (g) + \ce{O2} (g)\) |
A compound breaks down into two or more simpler substances (elements or compounds) |
| Single replacement |
\(X + YB \rightarrow XB + Y\) \(X + AY \rightarrow AX + Y\) Form 1 \(\ce{Zn} (s) + \ce{CuSO4} (aq) \rightarrow \ce{ZnSO4} (aq) + \ce{Cu} (s)\) Form 2 \(\ce{Cl2} (g) + 2\ce{KBr} (aq) \rightarrow 2\ce{KCl} (aq) + \ce{Br2} (l)\) |
In a single replacement reaction, one substance in a compound is replaced by another, more active, substance (an element). In this case one metal replaces another metal In this case one nonmetal replaces another nonmetal |
| Double replacement |
\(AB + CD \rightarrow AD + CB\) \(\ce{AgNO3} (aq) + \ce{NaCl} (aq) \rightarrow \ce{AgCl} (s) + \ce{NaNO3} (aq)\) |
The metal ions of two different ionic compounds can be thought of as “replacing one another” |
In a combination reaction, two or more substances (elements or compounds) combine to form a more complex substance. A decomposition reaction is the opposite of a combination reaction where a compound breaks down into two or more simpler substances. In a single replacement reaction, another, more active, substance (an element) replaces one substance in a compound. In a double replacement reaction, the metal ions of two different ionic compounds can be thought of as “replacing one another.” Most replacement reactions, both single and double, take place in aqueous solutions containing free ions. All of the types of reactions discussed here may be represented by balanced molecular equations. Reactions involving ion exchanges may be represented by ionic equations also. In this investigation, you will be concerned only with molecular formulas and equations. In a balanced equation, the number of atoms of any given element must be the same on both sides of the equation. Multiplying the coefficient and the subscript of an element must yield the same result on both sides of the balanced equation.
In this Lab you will learn how to write chemical reactions and how to use chemical reactions to identify different materials.
Special Instructions (if any)
N/A
Procedure
\(\PageIndex{A}\): Burning a copper wire
1. Obtain a piece of copper wire. Using crucible tongs, hold the wire in the hottest part of a burner flame for 1-2 minutes.
2. Examine the wire and note any change in its appearance caused by heating.
3. Record your observations. Place the used copper in the solid waste container provided.
\(\PageIndex{B}\): Burning a magnesium ribbon
1. Place an evaporating dish near the base of the burner. Examine a piece of magnesium ribbon. Using crucible tongs, hold the sample in the burner flame until the magnesium starts to burn. DO NOT LOOK DIRECTLY AT THE FLAME. HOLD THE BURNING MAGNESIUM AWAY FROM YOU AND DIRECTLY OVER THE EVAPORATING DISH.
2. When the ribbon stops burning, put the remains in the evaporating dish. Examine this product carefully.
3. Record your observations. Place the product in the solid waste container and rinse the evaporating dish.
\(\PageIndex{C}\): Burning copper (II) carbonate
1. Place one heaping microspatula of copper (II) carbonate (\(\ce{CuCO3}\)) in a clean, dry test tube. Note the appearance of the sample.
2. Using a test tube holder, heat the \(\ce{CuCO3}\) strongly for about 2 minutes. If the \(\ce{CuCO3}\) begins to rise in the test tube, you can lightly tap the tube and it will fall to the bottom. Remove the test tube from the flame. Insert a burning wood splint into the test tube. (If \(\ce{CO2}\) is present, it will extinguish the flame.)
3. Note any change in appearance of the residue in the test tube. Record all observations.
4. Carefully place the powder in the solid waste container and rinse the test tube.
\(\PageIndex{D}\): Reactions of acid and metals
1. Add about 5 ml of 1.0 M hydrochloric acid (\(\ce{HCl}\)) to three clean test tubes CAUTION: HANDLE ACID WITH CARE. Keep test tube opening away from your body.
2. Carefully drop a few pieces of zinc metal (\(\ce{Zn}\)) into the acid in the first test tube. Record your observations
3. Carefully drop a few pieces of magnesium metal (\(\ce{Mg}\)) into the acid in the second test tube. Record your observations
4. Carefully drop a few pieces of copper metal (\(\ce{Cu}\)) into the acid in the third test tube. Record your observations
5. Record all observations. Pour contents of test tube in the waste container and rinse thoroughly with water.
\(\PageIndex{E}\): Reactions of copper (II) sulfate solution and zinc
1. Add about 3 mL of 1.0 M copper (II) sulfate solution to a test tube. Place a small amount of zinc metal in the solution. Note the appearance of the solution and the zinc before and after the reaction. (You may have to wait 20 minutes to see any changes in appearance.) If you cannot see a change in appearance, pour the contents of the test tube into an evaporating dish and observe.
2. Pour the substance into a waste container. Rinse the glassware.
\(\PageIndex{F}\): Reactions of lead (II) nitrate and potassium iodide
1. Add about 3 mL of 0.1 M lead (II) nitrate (\(\ce{Pb(NO3)2}\)) to a test tube. Note the appearance of the solution.
2. Add about 3mL of potassium iodide (\(\ce{KI}\)) in to another test tube. Note the appearance of the solution.
3. Pour the potassium iodide into the test tube containing the lead (II) nitrate. Record any observations.
4. Pour the contents of the test tube into the waste container when you are done. Rinse the glassware.
\(\PageIndex{G}\): Reaction of acids with carbonates
1. Add about 3 mL of 1.0 M \(\ce{HCl}\) solution in a test tube.
2. Add a small amount of solid sodium carbonate (\(\ce{Na2CO3}\)) to the test tube.
3. Observe and record what happens. Then, perform step 4 while the reaction is still visibly active.
4. Insert (do not drop) a burning wood splint into the test tube. Insert right below the rim. (If \(\ce{CO2}\) is present, it will extinguish the flame.)
5. Pour the substance into a waste container.
\(\PageIndex{H}\): Identification of Unknowns
After you have finished performing and observing different chemical reactions, you are now ready to put that knowledge in practice to evaluate fluid samples from patients (A, B, C) for the presence of heavy and toxic metals like lead or acids. Your task is as follows
1. Collect one vial with liquid sample and record the label or Patient ID.
2. Analyze your sample for the presence of toxic and heavy metals or strong acids
3. To do this identify a test and use the appropriate procedure from above
4. Observe and record your data in Table \(\PageIndex{2}\).
Experimental Report
\(\PageIndex{A}\): Burning a copper wire (\(\ce{Cu}\) + oxygen \(\rightarrow\) copper (II) oxide)
Initial \(\ce{Cu}\) appearance: ______________________________________________________________________
Final appearance: _________________________________________________________________________
Balanced Equation: ________________________________________________________________________
Type of reaction: __________________________________________________________________________
\(\PageIndex{B}\): Burning a magnesium ribbon (\(\ce{Mg}\) + oxygen \(\rightarrow\) magnesium oxide)
Initial Magnesium appearance: ________________________________________________________________
Final appearance: _____________________________________________________________________________
Balanced Equation: ___________________________________________________________________________
Type of reaction: _____________________________________________________________________________
\(\PageIndex{C}\): Burning copper (II) carbonate (\(\ce{CuCO3}\) \(\rightarrow\) copper (II) oxide and carbon dioxide)
Initial \(\ce{CuCO3}\) appearance: __________________________________________________________________
Final appearance: _________________________________________________________________________
Balanced Equation: ________________________________________________________________________
Type of reaction: __________________________________________________________________________
\(\PageIndex{D}\): Reactions of acid and metals (metal + \(\ce{HCl}\) \(\rightarrow\) hydrogen gas + salt or ionic compound with chloride)
Add \(\ce{Zn}\) to acid observation: _____________________________________________________________
Add \(\ce{Mg}\) to acid observation: _____________________________________________________________
Add \(\ce{Cu}\) to acid observation: ______________________________________________________________
Balanced Equations: _______________________________________________________________________
_______________________________________________________________________
__________________________________________________________________________
Type of reaction: __________________________________________________________________________
\(\PageIndex{E}\): Reactions of copper (II) sulfate solution and zinc
Initial appearance: ___________________________________________________________________
Final appearance: ____________________________________________________________________
Balanced Equation: ___________________________________________________________________
Type of reaction: _____________________________________________________________________
\(\PageIndex{F}\): Reactions of lead (II) nitrate and potassium iodide
Initial appearance: ___________________________________________________________________
Final appearance: ____________________________________________________________________
Balanced Equation: ___________________________________________________________________
Type of reaction: _____________________________________________________________________
\(\PageIndex{G}\): Reaction of acids with carbonates
Initial appearance: ___________________________________________________________________
Final appearance: ____________________________________________________________________
Balanced Equation: ___________________________________________________________________
Type(s) of reaction: _____________________________________________________________________
\(\PageIndex{H}\): Identification of Unknowns
Patient Label:
Table \(\PageIndex{2}\): Data for the unknown sample
| Name of Test Performed | Observations | Substance present |
|---|---|---|
Provide a brief summary explaining how you arrived at you answer:
Follow-up questions
Balance the following reactions and identify the type of reactions:
a. \(\text{ ___ } \ce{AgNO3} (aq) + \text{ ___ } \ce{Cu} (s) \rightarrow \text{ ___ } \ce{Cu(NO3)2} (aq) + \text{ ___ } \ce{Ag} (s)\)
Type of Reaction: ___________________________
b. \(\text{ ___ } \ce{BaCl2} (aq) + \text{ ___ } \ce{Na2SO4} (aq) \rightarrow \text{ ___ } \ce{BaSO4} (s) + \text{ ___ } \ce{NaCl} (aq)\)
Type of Reaction: ___________________________
c. \(\text{ ___ } \ce{Cl2} (g) + \text{ ___ } \ce{NaBr} (aq) \rightarrow \text{ ___ } \ce{NaCl} (aq) + \text{ ___ } \ce{Br2} (l)\)
Type of Reaction: ___________________________
d. \(\text{ ___ } \ce{KClO3} (s) \rightarrow \text{ ___ } \ce{KCl} (s) + \text{ ___ } \ce{O2} (g)\)
Type of Reaction: ___________________________
e. \(\text{ ___ } \ce{AlCl3} (aq) + \text{ ___ } \ce{NH4OH} (aq) \rightarrow \text{ ___ } \ce{NH4Cl} (aq) + \text{ ___ } \ce{Al(OH)3} (s)\)
Type of Reaction: ___________________________
f. \(\text{ ___ } \ce{H2} (g) + \text{ ___ } \ce{O2} (g) \rightarrow \text{ ___ } \ce{H2O} (g)\)
Type of Reaction: ___________________________
Write an equation for the following reactions. Write the correct formulas of the reactants and products. Then correctly balance each equation.
a. Potassium and oxygen gas react to form potassium oxide.
b. Sodium and water react to form sodium hydroxide and hydrogen gas
c. Iron and oxygen gas react to form iron (III) oxide
Clinical application questions: This question will explore how chemical reactions can be used to relieve health symptoms.
a. What is the primary component of stomach acid?
b. What are the active ingredients of antacids?
c. Write a balanced equation between the stomach acid (in a.) and the calcium carbonate (one of the active ingredients of antacids) and identify the type of the chemical reaction.
Clinical application questions: This question will explore how chemical reactions can be used to help clinical diagnostic problems.
a. Blood glucose test measures the level of glucose in the blood using enzymes. What is the molecular formula of glucose?
b. In the blood glucose test, glucose (\(\ce{C6H12O6}\)) is converted to gluconic acid (\(\ce{C6H12O7}\)) by reaction with oxygen (\(\ce{O2}\)) with the help of an enzyme (glucose oxidase enzyme, GOx or GOD, also known as notatin). Given the molecular formulae of the molecules, write a balanced equation for this conversion and identify the type of the chemical reaction. Note that the enzyme is not included in the chemical reaction.