Ooo, if our chemical safety folks heard you say that!! ;^>
Actually, the CO2 is the chemical which, when dissolved in water,
renders the water acidic. In other words some chemical change does occur;
although, the concentration would hardly be substantial.
What about a small "hobby" bottle of N2 or He used in Hobby Shops
to blow up party balloons? They must be fairly easy to obtain these days.
If this was already suggested; sorry, I just jumped in here one late evening.
-Scott