Where Does the Candle Wax Go?

Summary

This SciShow episode explains how a burning candle works and where the wax goes. It highlights that the wax doesn't just disappear; instead, it combusts, turning into carbon dioxide and water vapor. The video compares the process to how fuel in a car burns and vanishes. The host dives into the science of combustion, how candles were an improvement over oil lamps, and even offers a fun trick involving a blown-out candle. Finally, the video is sponsored by Linode Cloud Computing, offering tools to keep cloud infrastructure secure and updated.

Takeaways

• 🕯️ The candle wick burns to produce heat and light, but after a while, the candle disappears.
• 🔥 Candle wax is a fuel, similar to gas in a car, and it burns to release energy through combustion.
• 🛠️ Candles were a significant innovation compared to oil lamps, which were prone to accidents and used plant or animal oils.
• 🧪 Combustion is a chemical reaction where a carbon-containing molecule (like wax or oil) combines with oxygen, producing carbon dioxide and water.
• 🔬 Modern candles use waxes, which are structurally similar to fatty acids in oil lamps but more convenient to use as solid fuel.
• 💧 The wax near the flame melts, vaporizes into a gas, and burns, creating carbon dioxide and water vapor.
• 🌫️ Blowing out a candle produces smoke, which is actually unburned wax vapor that cools down and condenses into tiny droplets.
• 🔥 A match can reignite a blown-out candle by following the stream of vaporized wax back to the wick.
• 🚗 A burning candle is similar to a gas tank running out, except instead of movement, it produces light and better-smelling air.
• ☁️ The video sponsor, Linode Cloud Computing, helps protect cloud data and provides tools to automate security updates.

Q & A

What happens to the candle wax as it burns?

The candle wax is vaporized, reacts with oxygen, and undergoes combustion, turning into carbon dioxide and water, which are released as gases.

Why doesn’t the wick burn as much as the candle wax?

The wick draws melted wax upward, which vaporizes and combusts. The wick itself doesn't burn much because it is mostly acting as a conduit for the wax.

How did oil lamps function before candles were invented?

Oil lamps used a wick laid in a shallow dish filled with oil. The wick would draw up the oil, allowing it to vaporize and combust when exposed to a flame.

What makes candles a safer alternative to oil lamps?

Candles use solid wax as fuel, which is less likely to spill and cause accidental fires, making them safer compared to oil lamps, which used liquid fuel that could easily ignite if spilled.

What is the main chemical reaction happening when a candle burns?

The main chemical reaction is combustion, where carbon-containing molecules in the wax react with oxygen to produce carbon dioxide, water, and release energy in the form of heat and light.

Why can you relight a candle by holding a match near the smoke after it is blown out?

The smoke contains unburned, vaporized wax. When you hold a flame near it, the wax vapor ignites, and the flame follows the trail back down to the wick, relighting the candle.

What does the smoke you see after blowing out a candle represent?

The smoke consists of unburned wax particles that have vaporized, but didn’t have enough oxygen or heat to combust, so they cool down and condense into tiny solid wax droplets.

Why does a candle go out when a cup is placed over it?

The candle goes out because the oxygen inside the cup is quickly used up, and the increasing concentration of carbon dioxide prevents further combustion.

Why were candles considered an innovation over oil lamps?

Candles were more convenient and safer than oil lamps, as the solid wax served as both fuel and lamp, preventing the risk of spilling flammable liquids and making them easier to transport and use.

What happens to the water produced by the combustion of candle wax?

The water produced by the combustion of candle wax is in the form of water vapor, which can condense if a cold object is placed near the flame.