Open the Valve and Count

You'll learnwhat entropy actually counts, how to read the sign of ΔS off a phase or volume change, and why released heat tells you nothing about it.

A bulb of gas sits beside an empty one behind a closed valve. Open it and nothing much seems to happen — no heat moves, no work is done — yet the entropy of that gas rises sharply. Twelve short steps; press Next for each one.

12 STEPS · 6 QUICK CHECKS · S COUNTS ARRANGEMENTS · SOLID < LIQUID ≪ GAS · v2

two bulbs, one valve · and a count that jumps with no heat

Before you start

What you're looking at

A bulb of gas beside an empty bulb, joined by a tube with a closed valve.

The question

Open the valve and no heat moves at all. So why does the entropy go up?

Step 1 / 12