Is suckback possible after removing stopper?

I am making hydrogen gas to fill a balloon. I will run the gas to a washing bottle with $\ce{NaOH}$ and then connect the balloon. I was wondering what would happen if I removed the stopper of my main reaction flask (e.g. to change wasted reagents) when the balloon is already half inflated.

1. Would $\ce{NaOH}$ get sucked out of the washing bottle somehow?
2. Would gas that's already in the balloon come out? Or the washing solution would prevent it?

• What are you mixing with NaOH to give you hydrogen gas? This wouldn't be the most common way of generating small amounts of hydrogen in the lab – NotEvans. May 21 '17 at 10:36
• I am mixing HCl with aluminium and bubbling the gas through NaOH. – Halo May 21 '17 at 10:48
• A picture (or drawing) of your apparatus would be worth a thousand words. – airhuff May 21 '17 at 19:54
• @airhuff I have made the edit. – Halo May 22 '17 at 6:32
• It looks like you'd be pretty safe to clamp the balloon then remove the stopper. You probably know this, but absolutely wear safety goggles. – airhuff May 25 '17 at 4:27