During this episode Adam and Jamie used sodium and potassium metals to put a hole in a wall to no avail.

Question:
Would the very much more reactive alkali metals rubidium and cesium have the desired effect?

Choices:
2g sample of rubidium will blow a hole in a plastic bath full of water'
A 2g sample of cesium metal will blow a plastic bath in half! In both cases the hydrogen gas that is released from the reaction with water explodes!

 

Rubidium and Caesium may be more reactive at an atomic level than Sodium and Potassium, but each atom is also a lot heavier. Therefore 2g of the stuff will have far fewer atoms.

Brainiac dropped alkali metals in bathtubs, and got into a bit of trouble because they faked it to give an explosion, when in fact very little happened with the heavier ones:

From badscience.net:

quote:

But what really happened? Deep Throat (okay, Brainiac's Dr Bunhead, aka Tom Pringle) claims: "Absolutely bloody nothing. The density of caesium ensured it hit the bottom of the bath like a lead weight. The sheer volume of water then totally drowned out the thermal shock-wave I was expecting to shatter the bath. This was an expensive filming day. They had hired part of Pinewood studios and had an ambulance and fire engine plus crew on standby. They could not go home empty handed. So they rigged a bomb in the bottom of the bath (you can see the black wire leading into the bath) and then blew the **** out of it. I must say it did look cool! [It] ate away at my conscience. But I couldn’t do anything about it."

When the metal is completely submerged, there is also no oxygen to react with the released hydrogen, so the gas escapes without being burned off. A sodium reaction is so violent because it floats on a cushion of created hydrogen, and the heat of that reaction causes the gas to burn in the air. Under water that cannot happen.

you are talking total rubish check any science book and in a list of properties of alkali metals and you will see the their dinsity is so low that they float on water

PS it also seems to me that anywhere that has pure alkali metals will also have other chemicals around. If you want to increase the efectiveness of this simply replace the water with acid if thats still not enough use one of the more reactive metals

quote:

Originally posted by dcross22:
you are talking total rubish check any science book and in a list of properties of alkali metals and you will see the their dinsity is so low that they float on water

Caesium and Rubidium are heavier than water (1.9 and 1.5 times respectively).

quote:

Originally posted by dcross22:
you are talking total rubish check any science book and in a list of properties of alkali metals and you will see the their dinsity is so low that they float on water

Some do - some don't, below is a list of some elements - including alkali metals & rare earths with their specific gravity, any with an S.G. of less than 1 will float on water, greater than 1 will sink.

Barium.........3.62
Beryllium......1.848
Calcium........1.55
Carbon.........2.26
Cerium.........6.77
Cesium.........1.873
Dysprosium.....8.55
Erbium.........9.066
Europium.......5.244
Gadolinium.....7.9
Gallium........5.91
Gold...........19.32
Hafnium........13.31
Holmium........8.795
Iodine.........4.93
Lanthanum......6.17
Lithium........0.53
Magnesium......1.738
Neodymium......7.00
Phosphorus.....2.34
Potassium......0.856
Praseodymium...6.77
Rubidium.......1.532
Samarium.......7.52
Scandium.......2.989
Selenium.......4.28
Sodium.........0.968
Terbium........8.27
Thulium........9.32
Titanium.......4.506
Water.......1.0
Ytterbium......6.97
Yttrium........4.47
Zirconium......6.506

I've included (& bolded) water to give a reference.

As you can see, there are just 3 that will float in water.

(I couldn't find the S.G. of Calcium, I had to extrapolate it from another quantity that I found.)

Caesium has an atomic weight of 133 compared to sodium's 23. Therefore if you have samples of sodium and caesium of equal mass, the sodium will have 133/23 = 5.8 times as many atoms.

Given also that caesium is denser than sodium, it will present a smaller surface area to the water.

This, combined with the fact that caesium sinks, means that throwing a chunk of it in a bathtub of water will be rather disappointing compared to the same weight of sodium.

This message has been edited. Last edited by: jaap,