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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: skitty on September 06, 2004, 12:22:27 PM

Title: Law of Conservation of Energy
Post by: skitty on September 06, 2004, 12:22:27 PM
An incandescent light bulb functions b/c of the flow of electric current. Does the the light bulb convert all of the electrical energy to light? Observe a functioning incandescent light bulb, and explain what occurs with reference to the Law of Conservation of Energy?

Okay, let me see if I got this right: Yes, all of the energy is converted to light b/c the Law of Conservation of Energy states that energy cannot be created nor destroyed in a chemical reaction (non-nuclear)  or in a physical change; it can only be converted from one for to another.  Right answer?
Thanks.
Title: Re:Law of Conservation of Energy
Post by: Demotivator on September 06, 2004, 01:37:39 PM
Hmm,  so you're saying that not heat is produced by the light bulb?
Title: Re:Law of Conservation of Energy
Post by: skitty on September 06, 2004, 02:13:15 PM
Yes, the light bulb produces heat.  And now I'm more confused than ever on something so fundamental.. :-[
Title: Re:Law of Conservation of Energy
Post by: Demotivator on September 06, 2004, 02:41:49 PM
Well, heat is also energy.  Most of the electric  current produces heat because wires like the  filament  have resistance to electric current. heat is enough to make the filament "white hot" emitting  some of the energy as light.
So, energy is conserved, but two forms of it are produced.
Title: Re:Law of Conservation of Energy
Post by: skitty on September 06, 2004, 03:06:28 PM
 ;D Thanks! Okay one more question: What is an example of The law of Conservation of Matter and Energy? I've picked my brain and ouch! it hurts. I know the answer is obvious and I can't see it.
Title: Re:Law of Conservation of Energy
Post by: Demotivator on September 06, 2004, 03:18:14 PM
Nuclear reactions can convert matter into energy.
Title: Re:Law of Conservation of Energy
Post by: jdurg on September 06, 2004, 03:41:33 PM
Any chemical reaction is also an example of how Mass and Energy are conserved in a reaction.  If you burn twenty grams of octane, the mass of the reactants and the mass of the products will be the same.  The energy involved in the chemical bonds is also conserved, though it changes form during the reaction.  
Title: Re:Law of Conservation of Energy
Post by: skitty on September 06, 2004, 05:27:34 PM
THANKS SO MUCH!!!!!!! ;D
Title: Re:Law of Conservation of Energy
Post by: ssssss on September 07, 2004, 04:55:27 AM
;D Thanks! Okay one more question: What is an example of The law of Conservation of Matter and Energy? I've picked my brain and ouch! it hurts. I know the answer is obvious and I can't see it.


To be more simple.Just read about the Mass defect.It says that when neutrons,protons and electrons build up together to form an atom there is slight difference in the mass of the resulting atom.This slight decrease in mass is converted into Binding Energy of Nucleus.

This energy can be calculated by Mass Energy Relation

E=mc2
Title: Re:Law of Conservation of Energy
Post by: ssssss on September 08, 2004, 02:10:25 AM
Ok i think the simpest example is nuclear fusion in Sun.