Materials

• Balloon (a helium party balloon - unfilled - from the dollar store)
  
  • mass: 10g
  • diameter (uninflated): 440mm
  • approximate volume: 10L
• NaOH: 11g
• Al foil: 8g

Expecting loss in H2, double amounts of NaOH & Al.

Procedure

• Fill water jug (bubbler) with water; leave 3cm air at top
• Fill flask with 500mL warm water
• Add 22g NaOH and dissolve
• Add 1-2g crumpled sheets of Al * Collect gas in balloon

Note: the procedure closely follows the approach demonstrated in NightHawkInLight's video, except using NaOH in place of HCl. More information on the reaction chemistry can be found here.

Observations

• With 2x NaOH mass, there was sufficient H2 production to also partially inflate a small grocery bag (a few L)
  • the reaction was slowing substantially towards the end, estimate 1.5x mass required next time
• Approximate rate of production was 10L in 45 minutes
• Add 1-2g of Al at a time and monitor temperature (reaction is exothermic)
  
  • adding Al requires removing the stopper from the flask, which likely mixes air in with the H2
• Filled balloon (10g) was buoyant with 10cm attached string using approximately 10L of H2 (10L should give 12g lift)
  • balloon filled to taught (lightly pressurized) lost some gas within a few minutes of disconnecting the feed and would yield easily when poked
  • filled balloon has dimensions of approximately 32cm diameter and 12.5cm height (approx 10L -- it's not a perfect cylinder)