[francoa]

What happens to the waste products from the Bunsen burners flame?

[Unknown008]

What do you think are the waste products?

A bunsen burner uses hydrocarbons as fuel (that is molecules containing carbon and hydrogen only).

Can you write an equation for the reaction? If so, I'm sure you can find the answer as to where the wastes go.

Post your answer! :)

[leif_erikson]

The waste goes off as carbon dioxide gas and water vapor. Those are the completely oxidized forms of carbon and hydrogen atoms which are found in hydrocarbon fuel. If you were to completely isolate an bunsen flame on a mass balance, you'd find that the mass increases as the flame burns longer and longer. That's because more and more waste gas accumulates. (well, if it's a closed vessel, then that means that oxygen will eventually run out and the flame will stop burning)

[Unknown008]

...

If you were to completely isolate an bunsen flame on a mass balance, you'd find that the mass increases as the flame burns longer and longer. That's because more and more waste gas accumulates.

...

Now you got me curious on that part you said. What do you exactly mean by isolating the Bunsen flame on a mass balance?

[leif_erikson]

"Completely isolating the bunsen fame on a mass balance".

A mass balance is a type of device for measuring the mass of an object.

Try to picture this, you have a very large container on a balance which gives a readout of whatever mass is on it. Let's say that you put a large container on the balance. Inside that container is a bunsen burner and a propane tank. When you allow the flame to burn, it will produce carbon dioxide and water. These gases will escape into the atmosphere around the flame. However because the container is closed, the mass remains constant as the reaction progresses. If you open the container, the gases will escape into the actual atmosphere and therefore, mass is being lost from the system. (which in this case is the container)

The example that I used in my previous post assumed that there was a bunsen flame inside of a closed container that was connected to a propane tank outside of the container. In that case, more propane (with mass) enters the system but is unable to leave after it is burned. Therefore the mass of the system within the container increases with time.

[Unknown008]

Ok, I was making sure that I understood what you meant.

On one hand, it's not that practical, because the mass will first increase, then stop as less and less oxygen is available for combustion.

On the other hand, if the container is not closed, the mass will remain constant (or rise at first, then reach a constant value) throughout as the waste gases will always be removed.

Well, the OP did not come back to answer the questions I asked him/her to help him/her understand the problem... Ok, here's how to test for the predicted gases.

Well, we know that a bunsen burner burns LPG, which are hydrocarbons. The equation is, in the case of methane:



The only products on complete combustion are carbon dioxide and water. We can then put an inverted funnel, sufficiently large to put in the Bunsen burner and its flame. A small space at the bottom of the funnel should be left though, to allow oxygen to enter the funnel to be burnt.

We then link the upper part of the funnel to a tube, to the other end of which we place just under the surface of a beaker containing lime water. The observation is that the lime water will turn milky, showing the presence of carbon dioxide in the gas evolved.

We can also stuff some anhydrous white copper (II) sulfate or anhydrous blue cobalt (II) chloride into the tube. If they turn blue, or pink depending on what you use, then, it means that water was present in the air.

Now, to answer the question, all the waste products, being gases, will go into the atmosphere.

[leif_erikson]

Yes, you are completely right.