Why there are different grades of Gas and the differences.


Why there are different grades of Gas and the differences.

In: Chemistry

It comes down to what it’s made of and thus what it can do.

CH4 is natural gas and used for various purposes to heat up.

Ethyn (C2H2) is used for welding for instance as it burns very hot with oxygen.

Hydrogen is also very flammable because it likes to react with everything.

Nitrogen is an inertgas and doesn’t really react with anything and is used to top of or flush vessels to make sure they don’t react with other gasses that could get in.

There are to many gasses to elaborate fully tho.

Gasoline is a liquid that’s a mix of “hydrocarbons” – a chemical that has hydrogen and carbon in it. There’s really light hydrocarbons like the butane in your lighter or the propane in your barbecue, and really heavy, solid hydrocarbons like the tar on your roof. Gasoline is in the middle of the bunch.

Each type of hydrocarbon molecule has a certain number of carbon atoms in it, and a certain number of hydrogen atoms. Propane has 3, and butane has 4, for example. And the less the number of carbon atoms, the faster it burns – this is why propane tanks can explode – but that comes with a lower amount of burning energy.

Gasoline is a mix of octane (8 carbon atoms) and nonane (9), and your car’s or lawn mower’s engine is specifically designed to best use a certain mix percentage of those two chemicals. Most cars love “regular” but special smaller motors often work best with “Premium” grade. Premium has a higher percentage of Octane compared to other hydrocarbons in it (that’s the number like 87 or 89 that you see on the pump – that means 87% octane or 89% octane – and premium used to be called “high-octane” for this reason.). Gas stations generally sell less of it, so they charge a little extra for it.

It goes the other way too, with some fuels having much more carbon in their molecules – diesel is a special fuel for a special type of engine that works with much bigger hydrocarbon molecules. It’s more energy-dense, and so is really good for big engines like transport trucks.

I assume you’re talking about the different grades of gasoline. The biggest difference between them is their octane rating.

The engine in a car mixes air and fuel, squeezes it together (compresses it) and then burns it. The more you can compress the air/fuel mix before burning it, the more power the engine can make.

If you compress the air/fuel mix too much, it will ignite too early and damage the engine. The difference between say regular and premium gasoline is how much you can compress the air/fuel mix without running into such problems.

High-performance engines are usually designed for high octane (premium) gas, whereas regular cars can use lower octane fuel.

The octane numbers you see at the pump relate to how much heat it takes to ignite the fuel in the engine. The higher the number the hotter it can withstand before it ignites. Why is this important? Most economy commuter cars, (think camry, accord, Taurus, etc) are designed for regular and that’s all they should ever need. But if you look at sports cars, especially turbocharged cars (WRX, stealth, Amg’s, etc) their engines create more power. That extra power causes the engine to run hotter so a gas that ignites at a lower temperature can cause it to ignite before it’s supposed to.

The additives and cleaners in gas are the same across the octane ratings in the same brand. So if your car takes regular, then just use regular. Theres no benefit to run a higher octane than what your car is calling for.