How can we combine two substances to make a hot pack or a cold pack?



By the end of this lesson, students will be able to combine two substances to make a hot pack or a cold pack.



First off, is there a chemical reaction or is there not? How do you know?




Set up a procedure and data table to collect information regarding these three combinations to determine what type of chemical reaction is occuring.

  1. Baking Soda + Calcium Chloride + Water
    NaHCO3 + CaCl2 + H2O
  2. Baking Soda + White Vinegar (Acetic Acid)
    NaHCO3 + CH3COOH
  3. Alka-Seltzer + Water

Check yourself:

Does your conclusion match with the data that you have collected?

If so, you are good to go!
If not, backtrack and revise your conclusion and note ways the experiment may have been incorrect OR revise your procedure and test again.


Standard Description


Develop models to describe the atomic composition of simple molecules and extended structures. [Clarification Statement: Emphasis is on developing models of molecules that vary in complexity. Examples of simple molecules could include ammonia and methanol. Examples of extended structures could include sodium chloride or diamonds. Examples of molecular-level models could include drawings, 3D ball and stick structures, or computer representations showing different molecules with different types of atoms.] [Assessment Boundary: Assessment does not include valence electrons and bonding energy, discussing the ionic nature of subunits of complex structures, or a complete description of all individual atoms in a complex molecule or extended structure.]


Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred. [Clarification Statement: Examples of reactions could include burning sugar or steel wool, fat reacting with sodium hydroxide, and mixing zinc with hydrogen chloride.] [Assessment Boundary: Assessment is limited to analysis of the following properties: density, melting point, boiling point, solubility, flammability, and odor.]


Develop and use a model to describe how the total number of atoms does not change in a chemical reaction and thus mass is conserved. [Clarification Statement: Emphasis is on law of conservation of matter and on physical models or drawings, including digital forms, that represent atoms.] [Assessment Boundary: Assessment does not include the use of atomic masses, balancing symbolic equations, or intermolecular forces.]


Undertake a design project to construct, test, and modify a device that either releases or absorbs thermal energy by chemical processes.* [Clarification Statement: Emphasis is on the design, controlling the transfer of energy to the environment, and modification of a device using factors such as type and concentration of a substance. Examples of designs could involve chemical reactions such as dissolving ammonium chloride or calcium chloride.][Assessment Boundary: Assessment is limited to the criteria of amount, time, and temperature of substance in testing the device.]


Analyze data from tests to determine similarities and differences among several design solutions to identify the best characteristics of each that can be combined into a new solution to better meet the criteria for success.


Develop a model to generate data for iterative testing and modification of a proposed object, tool, or process such that an optimal design can be achieved.