Force and Motion / Energy Review

 One of the observations that we made of the alkali metals is that the reaction with water converts larger and larger amounts of energy from lithium to cesium. 

None of the alkali metals are flammable so the fire and the and the explosions observed cannot be from the metals themselves and must be from the flammable hydrogen produced. 

Questions:

• If lithium's reaction with water produces hydrogen, why won't the hydrogen light on fire in this reaction?

• Sodium's reaction with water also produces hydrogen, and the hydrogen will light on fire but it does not happen immediately. 

• Potassium's reaction with water will light the hydrogen on fire immediately but this reaction is not nearly as explosive as the reactions between rubidium and water, and cesium in water.  Why is that? 

Things to consider:

• Hydrogen does not light on fire until the gas is about 600 C.   How do we explain the temperature increase? 

• More and more energy must mean more hydrogen.  How do you explain this?