Smells and fragrances work because tiny molecules from the object we're detecting get released into the air and carried into our nose. Tiny little receptors up near the back of the nostrils recieve these molecules as an input and send an electric signal to our brain which we interpret as smell. Now it turns out that charcoal is particularly good at absorbing these smells (in fact Buck Weimer has even begun marketing clothes containing charcoal to absorb unpleasant biological smells). But how does it work?
The answer is that charcoal has a huge surface area. Although a lump of charcoal looks like one little piece, if you zoom in the surface of a charcoal lump is filled with holes, tubes and craters (it is, after all, based on plant matter) which means a single gram of charcoal can have several square meters of surface area, all wrapped up into a tiny lump. Invisible to the naked eye, but a small molecule can easily navigate them.
The next effect is that two objects naturally cling to each other. What's called the London force effect (or, to give it its older name: the Van der Waals effect) two particles will naturally cling to each other because of the temporary charges dancing around on their surfaces. We don't notice this effect most of the time because it's very subtle. A marble on a table is easily picked up by the human hand, but we actually have to overcome a nanoscopic London force to separate it from the table. What this means is that small objects will cling to each other very, very well.
So charcoal works by having a lot of surface area, which small particles go colliding around on. This constant interacting between the charcoal's surface and the tiny particles leads to an overall "stickiness" to charcaol. Kind of like if we were to throw a dozen balls into a hedge, a lot of them would get caught up and tangled on the branches. Thus, charcoal (or anything with a large surface area) can absorb smells!
Mars has a composition very similar to Earth's. The surface is primarily made from Iron (III) Oxide which on Earth we usually call "rust". The rocks on the surface are otherwise quite similat to the types found on Earth. Most rocks are made from metal bonded to non metals like carbon, silicon, phosphorus and oxygen and this is exactly what we find on Mars. Mars has crystals the same we way do and it also has deposits of pure metals like Iron, much the same as Earth.
Where MArs is different to Earth is in the atmosphere and at the poles. Whereas our air is mostly Nitrogen with some oxygen and less than 1% Carbon dioxide (with the polar caps made of water), Mars' atmosphere is made of around 95% Carbon dioxide with some Nitrogen thrown in (the polar ice caps being made of solid Carbon dioxide).
We have also, of course, recently discovered liquid water on the surface of the planet, which means that Martian soil could support bacterial or even plant life similar to Earth's, but the air would make it unbreathable for Earth animals. The fact that there's virtually no oxygen in the air suggests there aren't any plants undergoing photosynthesis there however, so if we were to find cellular life there it would be very different in behaviour and chemistry to Earth life.
I've just started the topic of esters and esterification with my year 12s so this is fresh in my mind. An esterification reaction is where a carbon-based acid and an alcohol react together to produce an ester (a particularly fragrant and pleasant smelling chemical). Normally this reaction needs acidic conditions and heat to work. Sam's question is, would stomach acid and body temperature be enough to get the reaction going?
The first thing to point out is that most alcohols are completely toxic to humans (technically so is the ethanol in alcoholic drinks). But the main alcohols humans can safely consume are ethanol and methyl butanol, most others would be poisonous. Acids however are pretty common in our diet and there's a wide range your mouth and stomach can take.
Stomach acid can be as concentrated as pH 1.5 which is definitely enough to catalyse the reaction, the question is really about the body temperature of a human (37 degrees Celsius normally), could this be enough to get an esterification going? The answer seems to be a definite yes. There are lots of esterification reactions known to take place between room and body temperature so it's absolutely feasible to do the reaction in your stomach.
The problem is: your stomach has a lot of water in it, and water tends to break esters down. However they wouldn't reverse the reaction completely. What you'd end up would be a dynamic system where esters are constantly being made, and constantly being un-made until we reach a balance where they're being made as fast as they're being created. We call this a dynamic equilibrium. In this equilibrium, the amount of ester would probably be quite low as there's a lot more water in your stomach than ingredients (if you've outdone your own stomach capacity with alcohol and carbon based acid you need to see a doctor...and then a psychiatrist) but it is absolutely plausible to carry out esterifications in your stomach.
This is an excellent question and it's one which very rarely gets asked. Energy is a notoriously difficult thing to teach because a lot of people (even Scientists) are taught it incorrectly in the first place, so they pass on a faulty explanation to their students.
Let me start by saying what energy is not. It's not a substance. When an object "gains energy" this does not mean it's somehow got more stuff to it. An object higher up has gravitational potential energy, this doesn't mean you could somehow look at it and count the "energons".
Energy, defined as simply as possible, is "the ability to do work". Work means Force x distance moved in direction of Force. Force is a mass changing its velocity and velocity is a description of what something is doing. So, going backwards, Force is a measure of making something change what it's doing. Work is a measure of how much we've changed the thing, and Energy is a measure of the ability to do that.
If this sounds a bit abstract then it should. Energy is an abstract concept and we don't need it for any explanation. Ever. Unfortunately people use the term energy so often that they stop thinking about what it actually means and say things like "this happened because of Energy" or "Energy is what made it happen". This is cheating. Besides being a misuse of the word Energy.
For example, we might refer to fuel being burned, releasing its energy, making the car go. But this is not an explanation. This is like saying "the thing which makes the car go, is what makes it go". The thing making the car go is the movement of the particles and their collisions with the interior of the engine block.
The fuel particles are vibrating around a lot as they smash into each other. As the particles bump into the inside of the engine, the electrons in one atom repel the electrons in the other atom causing an overall repulsive effect, pushing the engine (and anything attached to it) forward, and the reacted fuel particles backward.
The question is how much fuel will lead to how much movement? This is what we use Energy for. We can measure the fuel's potential to react as its chemical energy. We can measure its speed using kinetic energy. We can measure the interactions between the colliding atoms as electromagnetic energy and so on. So, if we have (for each part of the process) an equation which translates the actual thing happening into a common unit (the Joule) we can easily move back and forth from process to process. The actual events happening are the particles moving and interacting, not "Energy being released" or "Energy changing form".
Energy should not, strictly speaking, be used as a noun. It should be used as an adjective because it is a measurement/description of something. Any time we talk about Energy in a Scientific concept, we have to remember that we need to qualify what the energy relates to. To say "this particle has energy" is meaningless. To say "this particle has kinetic energy" or "this particle contains a certain number of potential photons" is meaningful.
What Energy actually is, is a useful way of keeping track of cause and effect. It's a physicists way of quantifying "how much of this cause" will lead to "how much of this effect". In Einstein's infamous E=mc^2 formula, the E is not referring to some actual thing called energy. It is referring to the kinetic energy of massless particles (photons).
Another way to think of it would be to look at an object, a pencil say, and describe it as having a length. Length is not a substance, but a measurement telling you how much of the Universe the pencil takes up. The actual thing going on is particles are bonded together to form the shape of a pencil. We can quantify how much pencil there is by talking about its length but we cannot treat "length" as a substance and release it from the pencil or somehow give it more. It can't be created or destroyed for instance. You chop the pencil in half and you still have the same amount of length, just distributed differently. It's the same with Energy.
Ability to make things happen is what Energy is and you can't create it out of nowhere (a Physicist's way of saying: things don't happen without a cause) and you can't destroy it (you can't have a cause without an effect). So always remember that although Energy is a useful tool for keeping track of things, it is not a substance and never an explanation. Even when you hear distinguished Scientists talking about it as if it's an actual thing, remember this is just shorthand vocabulary.
Energy = ability to make a change to the Universe.