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## High school physics - NGSS

### Unit 3: Lesson 4

Energy at the microscopic scale

# Apply: energy at the microscopic scale

## Problem

Students observe their teacher mixing nitrogen and hydrogen gases in a jar to obtain ammonia:
\begin{aligned} \text{N}_2+3\,\text{H}_2 \to 2\,\text{NH}_3 \end{aligned}
The teacher allows them to touch the jar before and after the reaction. The students notice that the jar is warmer afterwards.
Which of the following caused the increase in thermal energy?