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Course: High school physics - NGSS > Unit 3

Lesson 4: Energy at the microscopic scale

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Apply: energy at the microscopic scale

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Students observe their teacher mixing nitrogen and hydrogen gases in a jar to obtain ammonia:

\begin{array}{r} N_{2} + 3 H_{2} \to 2 {NH}_{3} \end{array}

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?

(Choice A)
a decrease in electrical potential energy stored in molecular bonds
(Choice B)
a decrease in kinetic energy of the molecules
(Choice C)
an increase in gravitational potential energy of the molecules
(Choice D)
an increase in electrical potential energy stored in molecular bonds

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Video 5 minutes 58 seconds

Energy at the microscopic scale