What volume of dioxygen gas would be generated by complete decomposition of a #10*g# mass of #KClO_3#, under a pressure of #750*mm*Hg#?

1 Answer
Sep 3, 2017

Answer:

Well, we need a stoichiometric equation......and I get under #2*L#.

Explanation:

#KClO_3stackrel(MnO_2)rarr3/2O_2(g) + KCl#

Some #Mn(IV)# salt is usually added to catalyze the reaction.

#"Moles of potassium chlorate"=(10*g)/(122.55*g*mol^-1)#

#=0.0816*mol#

And thus we gets #3/2xx0.0816*mol=0.122*mol# #"dioxygen gas"#.

And then we simply solve the Ideal Gas equation.....

#V=(nRT)/P=(0.0816*molxx0.0821*(L*atm)/(K*mol)xx291*K)/((750*mm*Hg)/(760*mm*Hg*atm^-1))#

#=??*L#

Note the pressure measurement. A mercury column is a VERY convenient means to measure gas pressure in that we know that #1*atm# will support a column of mercury that is #760*mm# high. These days mercury has all but disappeared from laboratories because of perceived safety concerns. (I keep my manometers under lock and key, away from nosy safety inspectors).