4.4 Activity: Designing a Household Product Question How can endothermic and exothermic reactions be used to produce useful household products?
Background The formation of iron(III) oxide, from iron powder and oxygen gas from the air is very exothermic and produces 826 kJ/mol of iron(III) oxide ore. The dissolving of ammonium nitrate in water produces a solution of separated ammonium and nitrate ions. This physical change can be shown as NH4NO3(s) ➝ NH4+(aq) + NO3–(aq)
∆H = 25.7 kJ/mol
Procedure 1.
2.
Use the theoretical information provided above to design two useful products for treating athletic injuries. Present your designs in each of the following formats: • Describe each design in point form. • Provide a labeled diagram of each design. Compare your designs with those of a classmate. Use your comparison to improve your designs.
Results and Discussion 1.
Write a balanced thermochemical equation using the smallest possible whole number coefficients to describe the chemical change used in each of your designs.
2.
Which of the two reactions is useful for cooling a warm, inflamed injury?
3.
Which of the two reactions involves more bond breaking than bond forming?
4.
Assume 240 g of ammonium nitrate are dissolved in the second design. How many kJ of energy are absorbed during this reaction?
194 Chapter 4 Expressing and Measuring Chemical Change
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