Chapter 1 - Title

Demo Week II

“Whoosh Bottle”

• Bottle, alcohol, match• 2 effects

– Detonation“whoosh’ thrust (methanol)

– BurningCone/ring of fire (propanol)

• Depends on v.p., – All burn if diluted

• Fortman et al, 1999; Campbel et al., 2001

methanol > ethanol > 2-propanol > propanol

Safety

• No glass– Shatters

• Use air, NOT oxygen• Do not heat• Pressurized

– Avoid spray• Excess liquid melts the bottle

– Extinguish with cap• Goggles and safety shield

Procedure

• Add wheels• Jug MUST be dry• Add 0.75 mL methanol• Cap and slosh• Wait 20 mins

Rockets (Making Water)

• Fuel

HCl(aq) + Zn(s) ZnCl2(aq) + H2(g)

• Ignition

2H2(g) + O2(g) 2H2O(l)

Calculation

• Atmosphere provides 1 O2 molecule out of 5 we let in the bottle, Determine what ratio of H2 to air in a 2L bottle will provide a 2:1 ratio of H2:O2.

• Ratio O2 : N2 in air__ : __

• Ratio of Hydrogen : Oxygen in our rocket required for complete combustion

__ : __

• Ratio of Hydrogen : Air in our rocket required for complete combustion __ : __ (a : b)

__/__ : __/__ (divide by the total a+b)__% : __%

• ff

Solution

• 2H2 + O2 2H2O2 : 1 2

• Need 2 hydrogen molecules for every oxygen molecule• From air: 1 O2 for every 5 molecules of air we let in• Ratio of Hydrogen : Oxygen in our rocket required for complete

combustion

2 : 1• Ratio of Hydrogen : Air in our rocket

2 : 5 2/7 : 5/730% : 70%

• [1] ~ 570 mL of H2 and 1430 mL of air.