CHEM 151 Connecting Observations with Chemical Reactions the Produce Gases Lab
CHEM 151 Connecting Observations with Chemical Reactions the Produce Gases Lab
1. Group the solutions in Columns 1 – 12 based on how they responded to tests A – H. (All chemicals within a given group should have behaved the same.)
Figure 1: Data labels for tests and chemicals observed by student in the 96-well plate
Include both the item # and the chemical formula (e.g. #3 C3H7OH) in your lists. You should have four groups, and each chemical should be listed only once.
Table 1: Observing Trends
| Group 1 | Group 2 |
| Group 3 | Group 4 |
2. Examine your groups.
A) List the similarities in chemical behavior. Were there any differences in your groups?
B) Look at the formula for each chemical in each group. List similarities in the chemical formulas and bonding types within each group. Were there any differences?
Table 2: Chemical Behavior and Bonding Type
| Chemical Behavior | Chemical Formula & Bonding Type |
|||
| Group | Similarities | Differences | Similarities | Differences |
| 1 | ||||
| 2 | ||||
| 3 | ||||
| 4 |
Part IIA: Connecting Observations with Chemical Reactions the Produce Gases
A) Include a description and picture of the experimental set-up.
B) Based on the gas produced in the reaction between 1.0 M HCl (aq) and Mg (s) in a test tube.
What did you observe?
Based on your observations, write the overall (complete) balanced chemical equation for the reaction that occurs between HCl & Mg:
Write the complete (or total) ionic equation for the reaction:
Write the net ionic equation for the reaction and identify any spectator ions:
C) Based on the gas produced in the reaction between 1.0 M HCl (aq) and CaCO3 (s) in a test tube.
What did you observe?
Based on your observations, write the overall (complete) balanced chemical equation for the reaction that occurs between HCl & CaCO3:
Write complete (or total) ionic equation for the reaction:
Write the net ionic equation for the reaction and identify any spectator ions:
Part IIB: Connecting Observations with Writing Chemical Reactions
1. HCl and H2SO4 are both a class of compounds called acids. (Go back to your groupings in Table 1: Observation trends and label one grouping “ACIDS”)
a) Based on what you observed on part II what occurs when acids react with Mg.
b) Refer to the activity series from your pre-lab preparation.
i. Identify another metal that will react this way with HCl or H2SO4. __________
ii. Identify a metal that will not react this way with HCl or H2SO4. ____________
2. Using the skills you practiced in Skill Builder #4, write the complete, complete ionic, and net ionic equations for the reaction below. Refer to the solubility tables to help you determine physical states.
a) H2SO4 (aq) + Mg (s)
| Complete: | |
| Complete ionic: | |
| Net ionic: |
b) H2SO4 (aq) + CaCO3 (s)
| Complete: | |
| Complete ionic: | |
| Net ionic: |
c) Describe what occurs when acids react with compounds that contain carbonate CO32–.
d) Compare the reaction of HCl with CO32– and H2SO4 with CO32–.
3. Compounds that contain hydroxide (OH–) such as NaOH are bases. Label one of your groups in Table 1: Observation trends “BASES”.
Part III: Further Exploration of Acids and Bases
After reviewing the data from the students lab notebook, address the following questions:
1. Write an overall (complete) balanced chemical equation for each of the three reactions you observed. Note: the bromothymol blue is only acting as an indicator – it is the signal that tells you when you’ve added sufficient NaOH to react completely with the HCl, H2SO4 or HC2H3O2. Do not include bromothymol blue in the reaction you write. Example: Reaction #1 is between NaOH (aq) + HCl (aq). Write out the complete balanced equation.
2. Provide an explanation that supports the data for the relative number of drops of each acid needed to add to reach a color change. (We may use the averages number of drops for this part.)
3. Reflect on the students data and observations. Are there any improvements that you would recommend?
Part IV: Investigating Precipitation Reactions More in Depth
Analyzing solid formation in Part I: A common reaction type is a precipitation reaction, where a solid forms after mixing two aqueous solutions. Sometimes a precipitate just looks cloudy, so watch for cloudiness in a mixture as a sign of a precipitation reaction.
1. Look back at part I and review the students observation in the 96-well plate. A precipitate formed in some cases when you mixed the solutions with Mg(NO3)2 (aq).
a. Which solutions were they? (List the reagents, e.g Mg(NO3)2 + ______).
b. Refer to the solubility rules to help you. Predict the identity of the precipitates that formed in Part I when the solutions were mixed with Mg(NO3)2 (aq):
2. Consider each chemical that made a precipitate with Mg(NO3)2 (aq). Choose two of those chemicals. For each, write two balanced chemical equations: a) overall and b) net reaction with Mg(NO3)2 (aq).
3. Refer to the solubility rules to help you explain the observations below.
a. Why don’t the eggshells (CaCO3) dissolve in water?
b. Why was the Ca(OH)2 solution in Part I cloudy? (If you did not observe that it was cloudy, go check again. Shake the reagent bottle before observing.)
c. What is the type of bonding in Ca(OH)2. Did this solution conduct? Explain why or why not.
4. Refer to the solubility rules and reflect back on L2: Qualitative Results and review the qualitative test with AgNO3. (review the video if you need to):
| Chemicals to mix | Predicted Observation | Observed | Chemical Formula of Precipitate | Spectator ion |
| 0.1 M AgNO3 with 0.10 M NaCl | ||||
| 0.1 M AgNO3 with 0.1 M Ca(NO3)2 | ||||
| 0.1 M AgNO3 with 0.1 M KBr | ||||
| 0.1 M AgNO3 with 0.1 M Na2CO3 | ||||
| 0.10 M AgNO3 with 0.1 M Ba(NO3)2 |
5. Write a balanced overall chemical equation as well as a balanced net ionic equation for each reaction that produced a precipitate in Table 3.4 attachmentsSlide 1 of 4
UNFORMATTED ATTACHMENT PREVIEW
Part 1 – Observing Trends I. Watch the part I video to observe possible physical observations made during chemical reactions. https://sandiego.hosted.panopto.com/Panopto/Pages/Viewer.aspx?id=1d632c96-3e81-48e6-a355ac3d010e455b&start=5.959447 II. A student starts with a clean 96-well plate and placed each item/solution described in the row titles A – G into wells 1 – 12 of the corresponding rows in the plate (i.e., placed a piece of red litmus paper in wells A1 – A12, a piece of blue litmus paper in wells B1 – B12, etc.). III. Then the student placed 2 – 3 drops of each solution described in column titles 1 – 12 into the wells in rows A – G of the plate (e.g., put 2 – 3 drops of 1 M NaOH in wells A1, B1, C1, D1, E1, F1, and G1). Row Titles The test A – piece of red litmus paper B – piece of blue litmus paper C –
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CHEM 151 Connecting Observations with Chemical Reactions the Produce Gases Lab
1. Group the solutions in Columns 1 – 12 based on how they responded to tests A – H. (All chemicals within a given group should have behaved the same.)
Figure 1: Data labels for tests and chemicals observed by student in the 96-well plate
Include both the item # and the chemical formula (e.g. #3 C3H7OH) in your lists. You should have four groups, and each chemical should be listed only once.
Table 1: Observing Trends
| Group 1 | Group 2 |
| Group 3 | Group 4 |
2. Examine your groups.
A) List the similarities in chemical behavior. Were there any differences in your groups?
B) Look at the formula for each chemical in each group. List similarities in the chemical formulas and bonding types within each group. Were there any differences?
Table 2: Chemical Behavior and Bonding Type
| Chemical Behavior | Chemical Formula & Bonding Type |
|||
| Group | Similarities | Differences | Similarities | Differences |
| 1 | ||||
| 2 | ||||
| 3 | ||||
| 4 |
Part IIA: Connecting Observations with Chemical Reactions the Produce Gases
A) Include a description and picture of the experimental set-up.
B) Based on the gas produced in the reaction between 1.0 M HCl (aq) and Mg (s) in a test tube.
What did you observe?
Based on your observations, write the overall (complete) balanced chemical equation for the reaction that occurs between HCl & Mg:
Write the complete (or total) ionic equation for the reaction:
Write the net ionic equation for the reaction and identify any spectator ions:
C) Based on the gas produced in the reaction between 1.0 M HCl (aq) and CaCO3 (s) in a test tube.
What did you observe?
Based on your observations, write the overall (complete) balanced chemical equation for the reaction that occurs between HCl & CaCO3:
Write complete (or total) ionic equation for the reaction:
Write the net ionic equation for the reaction and identify any spectator ions:
Part IIB: Connecting Observations with Writing Chemical Reactions
1. HCl and H2SO4 are both a class of compounds called acids. (Go back to your groupings in Table 1: Observation trends and label one grouping “ACIDS”)
a) Based on what you observed on part II what occurs when acids react with Mg.
b) Refer to the activity series from your pre-lab preparation.
i. Identify another metal that will react this way with HCl or H2SO4. __________
ii. Identify a metal that will not react this way with HCl or H2SO4. ____________
2. Using the skills you practiced in Skill Builder #4, write the complete, complete ionic, and net ionic equations for the reaction below. Refer to the solubility tables to help you determine physical states.
a) H2SO4 (aq) + Mg (s)
| Complete: | |
| Complete ionic: | |
| Net ionic: |
b) H2SO4 (aq) + CaCO3 (s)
| Complete: | |
| Complete ionic: | |
| Net ionic: |
c) Describe what occurs when acids react with compounds that contain carbonate CO32–.
d) Compare the reaction of HCl with CO32– and H2SO4 with CO32–.
3. Compounds that contain hydroxide (OH–) such as NaOH are bases. Label one of your groups in Table 1: Observation trends “BASES”.
Part III: Further Exploration of Acids and Bases
After reviewing the data from the students lab notebook, address the following questions:
1. Write an overall (complete) balanced chemical equation for each of the three reactions you observed. Note: the bromothymol blue is only acting as an indicator – it is the signal that tells you when you’ve added sufficient NaOH to react completely with the HCl, H2SO4 or HC2H3O2. Do not include bromothymol blue in the reaction you write. Example: Reaction #1 is between NaOH (aq) + HCl (aq). Write out the complete balanced equation.
2. Provide an explanation that supports the data for the relative number of drops of each acid needed to add to reach a color change. (We may use the averages number of drops for this part.)
3. Reflect on the students data and observations. Are there any improvements that you would recommend?
Part IV: Investigating Precipitation Reactions More in Depth
Analyzing solid formation in Part I: A common reaction type is a precipitation reaction, where a solid forms after mixing two aqueous solutions. Sometimes a precipitate just looks cloudy, so watch for cloudiness in a mixture as a sign of a precipitation reaction.
1. Look back at part I and review the students observation in the 96-well plate. A precipitate formed in some cases when you mixed the solutions with Mg(NO3)2 (aq).
a. Which solutions were they? (List the reagents, e.g Mg(NO3)2 + ______).
b. Refer to the solubility rules to help you. Predict the identity of the precipitates that formed in Part I when the solutions were mixed with Mg(NO3)2 (aq):
2. Consider each chemical that made a precipitate with Mg(NO3)2 (aq). Choose two of those chemicals. For each, write two balanced chemical equations: a) overall and b) net reaction with Mg(NO3)2 (aq).
3. Refer to the solubility rules to help you explain the observations below.
a. Why don’t the eggshells (CaCO3) dissolve in water?
b. Why was the Ca(OH)2 solution in Part I cloudy? (If you did not observe that it was cloudy, go check again. Shake the reagent bottle before observing.)
c. What is the type of bonding in Ca(OH)2. Did this solution conduct? Explain why or why not.
4. Refer to the solubility rules and reflect back on L2: Qualitative Results and review the qualitative test with AgNO3. (review the video if you need to):
| Chemicals to mix | Predicted Observation | Observed | Chemical Formula of Precipitate | Spectator ion |
| 0.1 M AgNO3 with 0.10 M NaCl | ||||
| 0.1 M AgNO3 with 0.1 M Ca(NO3)2 | ||||
| 0.1 M AgNO3 with 0.1 M KBr | ||||
| 0.1 M AgNO3 with 0.1 M Na2CO3 | ||||
| 0.10 M AgNO3 with 0.1 M Ba(NO3)2 |
5. Write a balanced overall chemical equation as well as a balanced net ionic equation for each reaction that produced a precipitate in Table 3.4 attachmentsSlide 1 of 4
UNFORMATTED ATTACHMENT PREVIEW
Part 1 – Observing Trends I. Watch the part I video to observe possible physical observations made during chemical reactions. https://sandiego.hosted.panopto.com/Panopto/Pages/Viewer.aspx?id=1d632c96-3e81-48e6-a355ac3d010e455b&start=5.959447 II. A student starts with a clean 96-well plate and placed each item/solution described in the row titles A – G into wells 1 – 12 of the corresponding rows in the plate (i.e., placed a piece of red litmus paper in wells A1 – A12, a piece of blue litmus paper in wells B1 – B12, etc.). III. Then the student placed 2 – 3 drops of each solution described in column titles 1 – 12 into the wells in rows A – G of the plate (e.g., put 2 – 3 drops of 1 M NaOH in wells A1, B1, C1, D1, E1, F1, and G1). Row Titles The test A – piece of red litmus paper B – piece of blue litmus paper C –
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