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4: Experiment 4 - Chemical Reactions

  • Page ID
    214153
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    Learning Objectives

    Content:

    • Aqueous solutions
    • Solubility
    • Precipitation
    • Molecular, ionic and net ionic equations

    Process:

    • Mix chemicals, record your observations, write the molecular equation, ionic equation and net ionic equation.
    • Watch videos on this page. Before each video try to predict the outcome of the reaction. Write your observations, molecular equation, ionic equation and net ionic equation.

    Prior Knowledge:

    Aqueous solution is any solution where water is present as a solvent. Rain, vinegar, orange juice are all examples of aqueous solutions that you come across in your everyday life. In chemistry aqueous solution indicated by adding "(aq)" to the reactant formula. For example, NaCl(aq) present as individual ions Na+ and Cl- dissolved in water. You might have heard that water is the universal solvent, however, water only dissolves substances that are hydrophilic (from the Greek "hydros" - water and "philia" - bonding or friendship). Compounds that do not dissolve in water remain a solid and indicated by "(s)". For example, AgCl(s).

    Supplies

    • Magnesium sulfate
    • Calcium chloride
    • Copper (II) Sulfate
    • Sodi­um bi­car­bon­ate (baking soda)
    • Vinegar (~5% acidity)
    • Ammonia
    • Scale 
    • Clean and dry test tubes
    • Pipettes
    • Cell phone with camera
    • Laptop or computer with camera, speakers and microphone hooked up to internet

    Solubility rules could be useful in our everyday life, but they are also extremely important in medicine. Sometimes doctors prescribe more than one solution to be administered by the intravenous (IV) route. Mixing two solutions that form a precipitate can lead to very serious consequences. For example, magnesium sulfate is used as an electrolyte replenisher or anticonvulsant, calcium chloride is indicated in the immediate treatment of hypocalcemic tetany (abnormally low levels of calcium in the body that cause muscle spasm) and intravenous sodium bicarbonate is a medication primarily used to treat severe metabolic acidosis. But what will happen if you mix them?

     

     

    Procedure

    Safety:

    • Obtain and wear goggles and gloves!!!
    • Do non ingest any chemicals or inhale the vapors.
    • Clean up all spills immediately! If contact with skin rinse with water for 15 minutes.
    • No Lab Work will be performed outside the stated lab hours. 
    • All students must report back to their group by 10:40 and all data submitted to the TA by noon.
    • Before proceeding with this or any other experiment students must sign the chemical lab safety form.

    For each reaction in Part I and Part II record your observations, molecular equation, total ionic equation and net ionic equation. Make sure to write any evidence of any evidence of a chemical reaction with sufficient detail to help you distinguish between similar precipitation reactions. Don't write “became cloudy” or “white solid”. Indicate if a gel is produced or crystals form, if the solid was powdery, etc. Keep in mind that some reactions will not occur and you should write NR (no reaction). You will know that reaction occur if a precipitate, a gas, or stable molecule is formed. Heat (whether it consumed or evolved) can also be an indicator that reaction occurred.

    Make sure to write any evidence of any evidence of a chemical reaction with sufficient detail to help you distinguish between similar precipitation reactions.

    June 4, 2020

    Part I. Kitchen Chemistry Lab

    Perform Part I in your Kitchen Chemistry Lab. Mix about 3mL of each solution in a clean and dry test tube. Use pipettes to transfer solutions to test tubes. You must write all  equations for a given reaction before you start the next reaction. Keep your goggles on!

    You will be given the names of the compounds. You have to use formulas of these compounds for your equations. Mix each pair and record all required information. 

    1. Magnesium sulfate and calcium chloride
    2. Sodi­um bi­car­bon­ate and vinegar
    3. Sodi­um bi­car­bon­ate and calcium chloride
    4. Magnesium sulfate and sodi­um bi­car­bon­ate
    5. Ammonia and magnesium sulfate

    Waste disposal: Do not dispose of any solutions or solids down the drain.

    Part II. Video reactions

    Watch the videos. Before each video predict the outcome of the reaction. Write down your observations, molecular equation, ionic equation and net ionic equation for each reaction before moving to the next video. 

    1. Magnesium and hydrochloric acid

    Query \(\PageIndex{1}\)


    2. Copper(II)* sulfate and sodium phosphate

    Query \(\PageIndex{2}\)

     

    3. Cadmium (II) chloride and sodium sulfide

    Query \(\PageIndex{3}\)

     

    4. Nickel (II) chloride and sodium carbonate

    Query \(\PageIndex{4}\)

     

    5. Lead (II) nitrate** and sodium sulfide

    Query \(\PageIndex{5}\)

     

    6. Nickel(II) chloride and sodium phosphate

    Query \(\PageIndex{6}\)

     

    7. Silver nitrate and sodium carbonate

    Query \(\PageIndex{7}\)

     

     

    Interactive Element

    * The video says Cu2SO4, but the reaction shown in this video is between copper (II) sulfate and sodium phosphate.

    ** The video says Pb2NO3, but the reaction shown is between lead (II) nitrate and sodium sulfide

     

    June 5, 2020

    Use the Gravimetric Analysis Virtual Lab for this assignment. Read Part I, then work in groups to complete Part II. Part III is your individual assignment and every group member will have their own unknown. You should receive an email from the TA with the unknown solution you need to use for the individual section of this assignment.

    NOTE: If virtual lab says "Default Lab Setup" refresh your page

    it should say: "Gravimetric Analysis of Unknown Lead Solutions"

    Virtual Lab \(\PageIndex{1}\): ChemCollective Virtual Lab developed by Dave Yaron of Carnegie Mellon University, (http://www.chemcollective.org/). NOTE: if the lab loads as "Default Lab Setup" (with a bunch of acids, bases and indicators), refresh the page . You want it to load the "Gravimetric Analysis of Unknown Leas Solutions", which contains sodium chloride, potassium chromate and six unknowns.

    Interactive Element

    Contributors and Attributions

    Robert E. Belford (University of Arkansas Little Rock; Department of Chemistry). The breadth, depth and veracity of this work is the responsibility of Robert E. Belford, rebelford@ualr.edu. You should contact him if you have any concerns. This material has both original contributions, and content built upon prior contributions of the LibreTexts Community and other resources, including but not limited to:

    • Elena Lisitsyna
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