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Chemical Reactions

Investigation 1 – Lab

 

 

 

 

 

 

 

MINDSET

This Investigation is designed to:

  • illustrate to you that chemical reactions consume reactants and produce products,
  • allow you to analyze data indicating that energy in the form of heat can be released from a chemical reaction, and
  • allow you to measure the effect of increasing amounts of reactants on the heat produced by a reaction.

BE PREPARED

Student Preparation for the Investigation includes having students gather the following materials. This preparation takes place on lab day after student groups have settled at their assigned lab tables.

Note: The materials are listed in students’ SDRs. They are also listed below for your reference.

  • (1) 400 ml beaker
  • (2) 8 oz. insulated foam drinking cups
  • (1) pair of scissors
  • (1) thermometer
  • (1) 100 ml graduated cylinder
  • (1) 50 ml centrifuge tube filled with 30 ml of 2.7 g/100 ml ammonium hydroxide
  • (1) 50 ml centrifuge tube filled with 30 ml of 5.4 g/100 ml of ammonium hydroxide
  • (1) 50 ml centrifuge tube filled with 30 ml of 10.8 g/100 ml ammonium hydroxide
  • (1) 100 ml beaker filled with 30 ml of 2.7 g /100 ml of hydrochloric acid
  • (1) 100 ml beaker filled with 30 ml of 5.4 g/100 ml of hydrochloric acid
  • (1) 100 ml beaker filled with 30 ml of 10.8 g /100 ml of hydrochloric acid
  • (1) pair goggles per student
  • (1) pair gloves per student

Direct one student from each lab group to collect the materials listed in their SDRs.

 

INVESTIGATE

    • You will perform three Trials during this Investigation. Each Trial uses different amounts of the two reactants, ammonium hydroxide (NH4OH) and hydrochloric acid (HCl).
    • You should carry out each of the three Trials and record your data in Table A which is located at the end of the Investigation 1 Student Data Record.
    • As each Trial is completed, you should answer the questions within each Trial.
    • Reflect on the PreLab video as you move through the procedural steps.
    • During the Experiment, every procedural step is important. If one step is skipped, data can become invalid. To help you keep on track, read each step thoroughly, complete the step, then check it off (Read it – Do it – Check it).
    • Complete all procedural steps in your SDR.

    Note: The procedural steps are listed below for your reference.

    1. Construct a calorimeter by first placing one insulated foam cup in the 400 ml beaker.
      1. Use the scissors to cut off the rim of the second cup.
      2. Use the scissors to make a hole in the center of the cup. Push the thermometer through the hole and place the smaller cup in the larger cup and the larger cup in the 400 ml beaker.

     Trial 1

    1. In this Trial, you will react 2.7 g/100 ml of ammonium hydroxide (NH4OH) and 2.7 g/100 ml hydrochloric acid (HCl).
      1. Add 30 ml of 2.7 g/100 ml of ammonium hydroxide (NH4OH) to the bottom cup of the calorimeter. This is the first reactant in the reaction.
      2. Place the thermometer in the liquid. Slide the cup down the thermometer until it rests inside the bottom cup of the calorimeter.
      3. Wait until the temperature reading on the thermometer no longer changes.
      4. Record: Write the temperature of the liquid in Table A in the column under “Initial Temperature.” Table A is located on the last page of the Student Data Record.
      5. Locate the 30 ml of the 2.7 g/100 ml hydrochloric acid (HCl). This is the second reactant in the reaction.
    2. Remove the top cup of the calorimeter and the thermometer. Pour the hydrochloric acid (HCl) into the bottom cup and quickly replace the top cup and thermometer.
    3. Mix the reactants by carefully holding the beaker and swirling the calorimeter. Mix until the temperature reading on the thermometer no longer changes.
    4. Record: Write the temperature of the liquid in the column under “Final Temperature” in Table A which is located on the last page of the Student Data Record.
    5. Calculate: Find the temperature difference by subtracting the initial temperature from the final temperature.
    6. Record: Write the temperature difference in the last column of Table A.
    7. Empty the calorimeter and rinse with water. Shake out any excess water.

Trial 2

  • In this Trial, you will react 5.4 g/100 ml of ammonium hydroxide (NH4OH) and 5.4 g/100 ml hydrochloric acid (HCl).
  • Refer to Table A. In Trial 1, the concentrations of ammonium hydroxide (NH4OH) and hydrochloric acid (HCl) were both 2.7 g/100ml.
  • Add 30 ml of 5.4 g/100 ml of ammonium hydroxide (NH4OH) to the bottom cup of the calorimeter.
    1. Place the thermometer in the liquid. Slide the cup down the thermometer until it rests inside the bottom cup of the calorimeter.
    2. Wait until the temperature reading on the thermometer no longer changes.
    3. Record: Write the temperature of the liquid in Table A in the column under “Initial Temperature.”
    4. Locate the 30 ml of the 5.4 g/100 ml hydrochloric acid (HCl).
  • Remove the top cup of the calorimeter and the thermometer. Pour the hydrochloric acid (HCl) into the bottom cup and quickly replace the top cup and thermometer.
  • Mix the reactants by carefully holding the beaker and swirling the calorimeter. Mix until the temperature reading on the thermometer no longer changes.
  • Record: Write the temperature of the liquid in Table A in the column under “Final Temperature.”
  • Calculate: Find the temperature difference by subtracting the initial temperature from the final temperature.
  • Record: Write the temperature difference in the last column of Table A.

Empty the calorimeter and rinse with water. Shake out any excess water.

    1. Trial 3
      1. In this Trial, you will react 10.8 g/100 ml of ammonium hydroxide (NH4OH) and 10.8 g/100 ml hydrochloric acid (HCl).
      2. Refer to Table A. In Trial 2, the concentrations of ammonium hydroxide (NH4OH) and hydrochloric acid (HCl) were both 5.4 g/100ml.
      3. Add 30 ml of 10.8 g/100 ml of ammonium hydroxide (NH4OH) to the bottom cup of the calorimeter.
        1. Place the thermometer in the liquid. Slide the cup down the thermometer until it rests inside the bottom cup of the calorimeter.
        2. Wait until the temperature reading on the thermometer no longer changes.
        3. Record: Write the temperature of the liquid in Table A in the column under “Initial Temperature.”
        4. Locate the 30 ml of the 10.8 g/100 ml hydrochloric acid (HCl).
      4. Remove the top cup of the calorimeter and the thermometer. Pour the hydrochloric acid (HCl) into the bottom cup and quickly replace the top cup and thermometer.
      5. Mix the reactants by carefully holding the beaker and swirling the calorimeter. Mix until the temperature reading on the thermometer no longer changes.
      6. Record: Write the temperature of the liquid in Table A in the column under “Final Temperature.”
      7. Calculate: Find the temperature difference by subtracting the initial temperature from the final temperature.
      8. Record: Write the temperature difference in the last column of Table A.
      9. Empty the calorimeter and rinse with water. Shake out any excess water.

       

CLEAN UP

Be sure you and your group clean up your bench after completing your experiments.