Endothermic Reaction Chemistry Example 2

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Example 2

medium
An instant cold pack contains ammonium nitrate and water. When the inner bag is broken, the temperature drops from 25°C25°\text{C} to 5°C5°\text{C}. Classify the process and explain.

Solution

  1. 1
    The dissolving of NH4NO3\text{NH}_4\text{NO}_3 in water absorbs heat from the surroundings.
  2. 2
    The surroundings (water and your hand) lose heat, so the temperature drops.
  3. 3
    This is an endothermic process: the system absorbs energy (ΔH>0\Delta H > 0).

Answer

Endothermic process(ΔH>0)\text{Endothermic process}\quad (\Delta H > 0)
Cold packs work because the dissolution of certain salts is endothermic. The heat absorbed from the surroundings produces the cooling effect.

About Endothermic Reaction

A chemical reaction that absorbs energy (usually as heat) from the surroundings, resulting in a decrease in surrounding temperature and a positive enthalpy change (ΔH>0\Delta H > 0).

Learn more about Endothermic Reaction →

More Endothermic Reaction Examples

Example 1 easy

Photosynthesis absorbs energy: [formula]. Why is this endothermic?

Example 3 medium

Photosynthesis absorbs 2803 kJ per mole of glucose. Is it endothermic or exothermic? What is the sig

Example 4 easy

Cooking an egg requires continuous heat input. Is this an endothermic or exothermic process?

Example 5 easy

An instant cold pack becomes cold when activated. Is the process inside the pack exothermic or endot

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