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Fill in the blank to complete the sentence. Not all answer choices will be used.

This graph shows how temperature changes in
different chemical reactions in water.

2
The first bar in the graph shows the temperature change that occurs when ammonium chloride reacts with water. In this reaction, temperature decreases. Use the data to fill in the blanks and complete the sentence. Not all answer choices will be used.

When ammonium chloride reacts with water, the chemical reaction makes the surrounding water
by
degrees Celsius.

3
Which of these reactants cause an exothermic chemical reaction when combined with water? Select all correct answers. (Hint: Refer to the Key Terms tab above the graph)

Ammonium chloride

Calcium chloride

Magnesium chloride

Magnesium sulfate

Sodium acetate
4
Of the reactants you selected in Question 3, which one produces the most exothermic reaction when combined water? Briefly justify your answer.

5
Instant cold packs, like those used to treat injuries, start working when water mixes with ammonium chloride.

To design a pack that gets even colder, what temperature change must occur?

A
A decrease in temperature of less than 2°C

B
An increase in temperature of at least 23 °C

C
A decrease in temperature of more than 7 °C

D
An increase in temperature of less than 3 °C

1 answer

Here are the responses to your questions based on the provided information:

  1. When ammonium chloride reacts with water, the chemical reaction makes the surrounding water cooler by a certain number of degrees Celsius (you’ll need the specific data from the graph for the exact number).

  2. The reactants that cause an exothermic chemical reaction when combined with water are:

  • Calcium chloride
  • Magnesium chloride
  • Sodium acetate

(Ammonium chloride is endothermic, as it absorbs heat and thus causes a temperature decrease when dissolved in water.)

  1. Among the reactants selected in Question 3, Calcium chloride produces the most exothermic reaction when combined with water. This conclusion can be justified based on the comparative heat released during its dissolution compared to the other reactants listed.

  2. To design a pack that gets even colder, what temperature change must occur? C: A decrease in temperature of more than 7 °C. This would ensure a significantly colder effect, which is desirable for an instant cold pack.