Activation Energy

Paper burns readily. Yet a sheet of paper can lie on a table for years without catching fire. The reason is a kind of initial hurdle: before substances can react with one another, their building blocks must first absorb energy. This minimum portion of energy is called activation energy. Only once it is exceeded does the reaction begin – after that, it often delivers more energy than was put in. The term comes from chemistry, but today it’s also used in business and technology as an image for an initial hurdle.

Why gasoline doesn’t explode on its own

Without activation energy, the world would be a very restless place. Almost everything around us could react with the oxygen in the air: wood, paper, gasoline, even our skin. The fact that this doesn’t happen isn’t because these reactions are impossible. They’re simply held back because the initial hurdle is high.

It is precisely this hurdle that makes chemistry controllable. Anyone who wants a reaction lowers the hurdle or supplies energy – for example as heat, light, or electric current. Anyone who wants to prevent a reaction keeps the energy low. Refrigerators work on this principle: at 5 degrees Celsius, the molecules in food have much less kinetic energy than at 25 degrees. Decomposition reactions don’t stop entirely as a result, but they run noticeably slower.

An important distinction is often confused here. Activation energy says nothing about whether a reaction releases or absorbs energy overall. It only says how hard it is to get started. A reaction can release a lot of heat and still have a high starting hurdle. The burning of wood is exactly such a case.

The image of a hill between two valleys

The best way to picture the process is as a landscape. The starting substances sit in one valley, the products in a deeper valley. Between the two lies a hill. The ball doesn’t roll into the deeper valley on its own, because it first has to get over the hill. The height of this hill is the activation energy.

At the molecular level, the following happens: molecules are constantly moving and colliding. Only a small fraction of these collisions are forceful enough to break old bonds. If you raise the temperature, the molecules move faster. Then far more collisions manage to clear the hurdle. That’s why reactions often speed up dramatically with heat – as a rule of thumb, the rate doubles for every 10 degrees.

There is also a second way: the catalyst. This is a substance that enables the reaction without being consumed itself. It lowers the hill by offering a more comfortable detour. In car exhaust, platinum and rhodium convert toxic gases into more harmless ones this way. In our bodies, enzymes do the same thing: without them, digesting a bread roll would take years.

From chemistry class to business news

In everyday life, the term usually comes up wherever something is ignited or held back. A match supplies the activation energy for a campfire. A spark plug supplies it in an engine. An airbag ignites via an electrical impulse. And medications are stored cold so that their active ingredients don’t clear the hurdle to decomposition.

In business and technology news, activation energy often appears in connection with batteries and hydrogen. Splitting water into hydrogen and oxygen costs a great deal of energy – a large part of research revolves around catalysts that lower this hurdle. Whoever makes progress here directly lowers the cost of green energy. The term thermal runaway in battery fires also belongs here: once the hurdle has been crossed, the reaction keeps heating itself up further.

Finally, the term is used figuratively, including in texts about AI and startups. What is meant then is the effort required before something runs on its own: the first version of a product, the first users, the first training run of a model. This transfer is not a technical term but a metaphor – yet it works well because it captures the essence: the start is more expensive than ongoing operation.