Practice Endothermic Reaction in Chemistry
Use these practice problems to test your method after reviewing the concept explanation and worked examples.
Quick Recap
A chemical reaction that absorbs energy (usually as heat) from the surroundings, resulting in a decrease in surrounding temperature and a positive enthalpy change (\Delta H > 0).
The reaction needs heat to proceed — you can feel the surroundings get colder as it runs.
Example 1
easyPhotosynthesis absorbs energy: 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2. Why is this endothermic?
Example 2
mediumAn instant cold pack contains ammonium nitrate and water. When the inner bag is broken, the temperature drops from 25°\text{C} to 5°\text{C}. Classify the process and explain.
Example 3
mediumPhotosynthesis absorbs 2803 kJ per mole of glucose. Is it endothermic or exothermic? What is the sign of \Delta H?
Example 4
easyCooking an egg requires continuous heat input. Is this an endothermic or exothermic process?
Example 5
easyAn instant cold pack becomes cold when activated. Is the process inside the pack exothermic or endothermic? Explain.