Nothing Special   »   [go: up one dir, main page]
Scribd Logo
Upload

Welcome to Scribd!

  • 56 views

    Experiment #3 / Unit 6 Calorimetry - Measuring Heat Changes During A Physical or Chemical Change

    Uploaded by

    api-368121935
    This document describes an experiment using calorimetry to measure the heat changes that occur during physical and chemical changes. Students will use a coffee cup calorimeter to measure the temperature changes when dissolving ammonium chloride or nitrate salts in water, and when adding magnesium to hydrochloric acid. They will calculate the heat absorbed or released during these processes, and determine the heat of solution or reaction to compare to accepted literature values. Students are instructed to show all data, calculations, and questions in a lab report.

    Copyright:

    © All Rights Reserved
    Download as DOC, PDF, TXT or read online from Scribd

    Experiment #3 / Unit 6 Calorimetry - Measuring Heat Changes During A Physical or Chemical Change

    Uploaded by

    api-368121935
    56 views2 pages
    This document describes an experiment using calorimetry to measure the heat changes that occur during physical and chemical changes. Students will use a coffee cup calorimeter to measure the temperature changes when dissolving ammonium chloride or nitrate salts in water, and when adding magnesium to hydrochloric acid. They will calculate the heat absorbed or released during these processes, and determine the heat of solution or reaction to compare to accepted literature values. Students are instructed to show all data, calculations, and questions in a lab report.

    Original Description:

    Original Title

    e6

    Copyright

    © © All Rights Reserved

    Available Formats

    DOC, PDF, TXT or read online from Scribd

    Did you find this document useful?

    Is this content inappropriate?

    This document describes an experiment using calorimetry to measure the heat changes that occur during physical and chemical changes. Students will use a coffee cup calorimeter to measure the temperature changes when dissolving ammonium chloride or nitrate salts in water, and when adding magnesium to hydrochloric acid. They will calculate the heat absorbed or released during these processes, and determine the heat of solution or reaction to compare to accepted literature values. Students are instructed to show all data, calculations, and questions in a lab report.

    Copyright:

    © All Rights Reserved
    Download as DOC, PDF, TXT or read online from Scribd
    Download as doc, pdf, or txt
    56 views2 pages

    Experiment #3 / Unit 6 Calorimetry - Measuring Heat Changes During A Physical or Chemical Change

    Uploaded by

    api-368121935
    This document describes an experiment using calorimetry to measure the heat changes that occur during physical and chemical changes. Students will use a coffee cup calorimeter to measure the temperature changes when dissolving ammonium chloride or nitrate salts in water, and when adding magnesium to hydrochloric acid. They will calculate the heat absorbed or released during these processes, and determine the heat of solution or reaction to compare to accepted literature values. Students are instructed to show all data, calculations, and questions in a lab report.

    Copyright:

    © All Rights Reserved
    Download as DOC, PDF, TXT or read online from Scribd
    Download as doc, pdf, or txt
    of 2

    Experiment #3 / Unit 6

    Calorimetry - Measuring Heat Changes During a Physical or Chemical Change

    Introduction:
    Physical and chemical changes are accompanied by energy changes. This
    energy change normally involves heat. Physical and chemical changes may result in
    an intake of heat and cause the temperature of the surroundings to decrease (an
    endothermic change) or a release of heat that causes the temperature of the
    surroundings to increase (an exothermic change). "Calorimetry" is the experimental
    technique used to measure the heat gained/released in a physical or chemical
    change. Calorimetry is an indirect method because a temperature change can not be
    measured directly by putting a thermometer inside shuffling atoms. Calorimetry
    employs water as a heat sink which either provides the heat to an endothermic
    change or catches the heat produced by an exothermic change. The key to the
    technique is that it is easy to measure the temperature change and subsequent heat
    loss/gain for water. In this experiment, we will practice the technique of calorimetry by
    using a crude calorimeter system to measure the heat changes involved in the
    dissociation of ammonium chloride or ammonium nitrate (physical change) and the
    reaction of magnesium with hydrochloric acid.

    Procedure:
    Dissociation of an Ammonium Compound
    1. Obtain a coffee cup.
    2. Measure 50.x mL of tap water in a graduated cylinder and pour into the
    calorimeter. Set the cup in a beaker to stabilize it.
    3. Mass 7-10 g of the ammonium salt (you choose between ammonium chloride and
    ammonium nitrate) in a massing boat.
    4. Obtain a thermometer and record the initial temperature of the water.
    5. Add the salt and gently stir the solution with the thermometer and record the lowest
    temperature reached. Make sure all the solid has dissociated.
    6. Pour the solution into the recycle bucket and rinse the cup.

    Reaction of a Metal with Acid


    1. Obtain a coffee cup.
    2. Measure 50.x mL of 0.50 M hydrochloric acid in a graduated cylinder and pour into
    the calorimeter. Set the cup in a beaker to stabilize it.
    3. Cut approximately 15 cm of Mg ribbon and mass it.
    4. Obtain a thermometer and record the initial temperature of the water.
    5. Add the metal and gently stir the solution with the thermometer and record the
    highest temperature reached.
    6. Dispose of the solution.

    Chemistry Raleigh Charter High School Dr. Genez


    1
    Data:
    Dissociation of an Ammonium Compound
     volume of water
     identity of salt
     mass of ammonium salt
     initial temperature of the water
     lowest temperature reached by the solution

    Reaction of a Metal with Acid


     volume of acid
     mass of magnesium
     initial temperature of the acid solution
     highest temperature reached by the solution

    Calculations and Questions:


    Dissociation of an Ammonium Compound
    1. Write an equation for the dissociation of the salt. Include heat as a product/reactant
    as appropriate.
    2. Calculate the mass of the solution.
    3. Calculate the heat lost by the solution in calories. Use 0.925 cal/g x oC as the
    specific heat capacity of the solution.
    4. How many calories did the dissociation process absorb?
    5. Calculate the heat of solution (Hsoln) in kJ/mol for the ammonium salt.
    6. Calculate the percent error for the experiment. The accepted value for the Hsoln of
    NH4NO3 is +26.0 kJ/mol and NH4Cl is +16.0 kJ/mol.

    Reaction of a Metal with Acid


    1. Write both a total molecular and net ionic equation for the reaction. Include heat as
    a product/reactant as appropriate..
    2. Calculate the mass of the solution. Use 1.01 g/mL as the density of 0.50 M HCl.
    3. Calculate the heat gained by the solution in calories. Use 0.952 cal/g x oC as its
    specific heat capacity.
    4. How many calories did the reaction produce?
    5. Calculate the heat of reaction (Hrxn) in kcal/mol for the magnesium.
    6. Calculate the percent error for the experiment. The accepted value for the Hrxn of
    Mg is -110.41 kcal/mol.

    Lab Report #6.3:


     title page
     procedure sheet
     data
     calculations and questions

    Chemistry Raleigh Charter High School Dr. Genez


    2

    You might also like