[ondabox]

I am sorry if this question doesn't live up to the standards expected here. I am seeking an answer as to whether there is a "law" or "principle" in chemistry that generally equates to Newton's third law re; Equal and opposite reaction...however, I am not wondering whether the reaction is "opposite" as such, but I am wondering if you can change the ratios of two or more chemicals in any experiment without an effect? For example: Is there ANY chemical I can add 1 drop of to water, other than water, that has NO effect , or is there ALWAYS some effect, even if has no net change to the properties and function of the water?

[Arkcon]

Hard to follow, but to try and help you figure it out, ... no, there is no such chemical law.  This is, at the face of it, a fundamental difference between chemistry, or biology and physics or mathematics -- what appears to be a lack of fundamental laws.  This is something that appears to be true, but only at the surface.  You're looking for a chemical law, that will apply, to a certain subset of substrates the same as the very general third law of Newton's laws of motion, applies to theoretical particle motion.  We're doomed from the start, in this case.

More specifically, certainly there are substances that are inert and nonreactive to water -- I think gold would or platinum would fall under that, very general, heading.

[fledarmus]

Like Arkcon, I'm not sure exactly what you are trying to ask, but I do see some similarity in your question to LeChatelier's Principle. In one form, it can be thought of as saying that if a reaction is at equilibrium, with both starting materials and products present, then increasing the concentration of the starting materials will cause more product to be formed, while increasing the concentration of the product will cause more starting material to be formed. A more thorough explanation can be found in wikipedia: http://en.wikipedia.org/wiki/Le_Chatelier%27s_principle

If you could give some context for your question, we might be able to come up with a more helpful answer

[ondabox]

Wow, thanks for the replies.

I suppose, with respect to the first answer re adding gold etc to water...would increase the volume...so it has a net effect in my opinion. With respect to the second answer...I suppose I think it comes close...However, it does not necessarily have to involve a "reaction" that "produces" something.

Contextually, my ulterior motive was to point out to a climate change sceptic, that although he may not agree Co2 ppm increase causes warming, I wanted him to realise that you cannot "add" Co2 to the atmosphere without it having "some" effect....I wanted to point him to a principle that basically states that if you change the ratio of component gases in a chamber, then, despite what the result is, there is "always" "some" change, whether it be net warming capacity or not.

Wow...my messages are long winded and hard to follow...sorry.

[ondabox]

So, I suppose, my version of such a law would read:

"Addition or subtraction of any chemical or compound (reactant) to a system always has a net effect. Whether it be to mass, volume, temperature or other" ....Am I close?

Forgive my ignorance if this post seems ridiculously plain.

[fledarmus]

"Addition or subtraction of any chemical or compound (reactant) to a system always has a net effect. Whether it be to mass, volume, temperature or other" ....Am I close?

Well, this is true, but absolutely useless as a starting point in a conversion. All you are saying is that if B≠0, then A+B ≠ A. Adding a marble to a car changes the mass of the car, and if you've been carrying the marble around in your pocket, it changes the temperature of the car as well.

The problem with climate science is that so many processes are happening at once, and they are all influenced by so many factors. Plants and oceans absorb carbon dioxide from the atmosphere, animals, volcanoes, and fires return carbon dioxide to the atmosphere, and many very small scale and very large scale processes are exquisitely sensitive to the concentration of carbon dioxide in the atmosphere. And the carbon dioxide that is put into the atmosphere does not magically appear out of nowhere - it has to come from something, and the concentration of that something is also being reduced when carbon dioxide is being emitted. It takes an extremely elaborate model of climate change to even begin to consider modeling the concentration of carbon dioxide in the atmosphere, and if you want to couple that to temperature, then you have an equally elaborate if not more elaborate model to couple it to. Since you've already established that A+B ≠ A, you know that something will happen if you add carbon dioxide to the air, but trying to determine what it is can be a nightmare. And when you are concerned not just with A and B but with A+B+C+D+E+F+G+H+I+J+K+L+M+N+O+P, each of which depends on every other term, there is no telling where you might end up.

[ondabox]

I do see your point regarding the basic principle i.e change=change and with respect to climate change how the system is complex. I suppose I would like to deal with the principle regarding changing of ratio of component gases in a chamber.

For example: Are there any two gases when the component ratios are changed in an isolated system that do not show a variation in their properties regarding heat retention?

[fledarmus]

Are there any two gases when the component ratios are changed in an isolated system that do not show a variation in their properties regarding heat retention?

You are asking the same question again. If B≠0, then A+B ≠ A. If gas A has one set of properties and gas B has another set of properties, then any mixture of gases A and B will have properties different from either A or B.

Perhaps it would help to move back to what a greenhouse gas is, since that seems to be the property you are most interested in. A greenhouse gas absorbs and re-emits radiation in the infrared range. Heat emitted from the planet, rather than passing straight through the atmosphere like a pane of glass, gets trapped and scattered back through the atmosphere.

All gases have different wavelengths of radiation that they will absorb and re-emit. Carbon dioxide and water happen to be strong absorbers of infrared radiation. Oxygen and ozone are strong UV absorbers. Each gas will have its own characteristic bands of energy that it absorbs; this is how the chemical makeup of extraterrestrial objects is determined.

Here is a picture of some atmospheric gas spectra that might help make the point:

http://en.wikipedia.org/wiki/File:Atmospheric_Transmission.png

So yes, if you have two gases mixed together in an isolated system, they will show a specific pattern of radiation absorption, and if you change the composition of the mixture, you will change which frequencies are absorbed and to what extent. Unless the two gases have identical absorption characteristics, it is not possible to change the composition of the mixture without changing the absorption characteristics of the mixture.

[ondabox]

Well, my last question was clearly not the same. I was asking whether there are any two gases that , when mixed in different ratios, share the same heat retention properties, not whether they share all properties in the same situation. I imagine, logically, that it would be possible for two gases mixed in different ratios to share the same heat retention properties i.e (gas x @1% /gas y@99%)=(gas x@99%/gas y @1%)-with respect to heat retention in an isolated system. If there are not two such gases...well it sort of illustrates my point.

[fledarmus]

And that was the way I answered your question. If the individual gases have different "heat retention properties" (however you would like to measure what is a vague description rather than a property), then any mixture of the two gases will have different "heat retention properties" than any other mixture. I then went on to describe how that applies when you are looking at infrared frequency absorption.

[ondabox]

Sorry. My last response was out of step with the response you had previously posted. I think we may have posted replies at nearly the same time, so your most current response at the time was not visible to me.

I totally understand your point ,however, are you able to just answer; "no" - "No two gases share thesame heat retention properties"?

i.e therefore, when you add Co2 to 'air', thus increasing its ratio to the other gases in air, as a result - It (air) will not share the same heat retention properties.

If this is true, as I assume from your response it obviously is, the question then becomes ; Are there any two gases that will share the same heat retention properties. It seems you are trying to imply that because by definition two gases are different, they will invariably share different heat retention properties. This is not, however, a self evident truth.

I assume there are no two such gases, thus making it a rule?

[fledarmus]

The problem is that you have to define exactly what you mean by "heat retention properties". That is not a standard phrase in chemistry or thermodynamics. You would have to pick your properties much more carefully and specifically to truly make this an all or nothing proposition. In the specific case of carbon dioxide and global warming, you can make the specific statements that:

• Carbon dioxide has a much stronger infrared absorption than most other gases.
• Any increase in the percentage of carbon dioxide in the atmosphere will lead to more absorption by the atmosphere of infrared radiation produced or reflected by the earth.
• Infrared absorption by the atmosphere is one mechanism by which heat may be retained.
• In an isolated system composed solely of carbon dioxide and a second gas having lower infrared absorption than carbon dioxide, with no mechanisms of heat retention other than infrared absorption, and with no mechanism for correcting any changes in concentration of the two gases, an increase in the percentage of carbon dioxide in the mixture would lead to an increase in heat retention of the mixture.
  

[Jorriss]

As someone else mentioned, the closest general principle to newton's third law is Le Chatelier's Principle. Interestingly enough, like Newton's third law, it turns out to not be exactly correct either!

[ondabox]

Thank you Fledarmus.

This is, primarily the response I was seeking. I know that 'heat retention' is not necessarily the correct terminology with which to phrase the question, but I hope (we all0 understand the reason for doing so.

With respect to your answer, I suppose it holds true that it applies to more than two gases in a system. Assuming the 'average' heat retention property of the mixture is increased by an increase of a component gas that has a higher heat retention property (in that it absorbs more infrared radiation).

[curiouscat]

Contextually, my ulterior motive was to point out to a climate change sceptic, that although he may not agree Co2 ppm increase causes warming, I wanted him to realise that you cannot "add" Co2 to the atmosphere without it having "some" effect....I wanted to point him to a principle that basically states that if you change the ratio of component gases in a chamber, then, despite what the result is, there is "always" "some" change, whether it be net warming capacity or not.

That is a bizarre argument though. "Some" change is essentially irrelevant; in any practical situation what we're interested in is whether it is a "significant"  change (with the amount that is significant varying in each case).

Also, be careful with the signs of things. "Some" change may not always be a "bad" change.