Since clouds are more dense than clear air, presumably this would this give the turbines more to chew on and increase the thrust somewhat. Although, moving into a denser air mass with microscopic droplets/ice crystals would also increase the friction.Who wins?

Stoichiometry easily proves that 1kg of water (55.556mol) produces about ~111g of H2 (55.556mol) and ~889g of O2 (27.778mol), which totals to 1kg of the two gases.

Say I am going to electrolysis the water. I have 1kg of water in a bottle-shaped container. At the top of the bottle, there is a flat balloon covering the opening.

Now I somehow get this water to start turning into hydrogen and oxygen. As this happens, the hydrogen and oxygen floats up and starts filling the balloon. The balloon gets bigger and bigger, as more water is used up.

The balloon is attached to the bottle such that it cannot simply float away.

Since the balloon weighs nothing, where is the weight gone? If this bottle setup was placed on a scale, then the scale would show that the bottle was getting lighter as water got turned into hydrogen and oxygen.

Okay, so I'm a firm believer in stoichiometry. So I have no problems believing that 1kg of water turns into 1kg of hydrogen + oxygen. However when presented with the case described above, I could not convincingly explain how water got turned into two lighter gasses. 

I know it has something to do with the relationship between density and weight, and the density of gasses vs. the density of air and how that affects the way weight is measured.

Can somebody give an explaination of the scenario described above?

Secondly, how does one go about measuring the weight of a gas (i.e. not calculating).

Lastly, any reliable sources to say that 1kg of water will turn into 1kg of gas?

Hypothetically, if you had a gas made of really heavy atoms/molecules (although it's unlikely that they would be stable at the kind of Uranium-heavy I'm thinking of, let's say that hypothetically they are) in a liquid made of really really light molecules or atoms (e.g hydrogen), and say that temperature isn't going to change the given states of the elements (very very hypothetically), and so they can exist in the states they need to together, could the bubbles go down? Or would the relative densities make the masses of the atoms and molecules irrelevant? 

I know the air inside the lungs makes people float and just like that,the air inside a ship decreases the density of the total volume and hence makes the ship float.But what happens if you vacuum the air inside the ship and then seal it somehow,just like exhaling air from your lungs,does the ship sink cause the density of the total volume will just be the density of them metals inside the ship despite the airless big space in it?