Answer:
Conditioning two or three times will insure that the concentration of titrant is not changed by a stray drop of water.
Explanation:
"Check the tip of the buret for an air bubble. To remove an air bubble, whack the side of the buret tip while solution is flowing".
Balance the chemical equation for the chemical reaction.
Convert the given information into moles.
Use stoichiometry for each individual reactant to find the mass of product produced.
The reactant that produces a lesser amount of product is the limiting reagent.
The reactant that produces a larger amount of product is the excess reagent.
To find the amount of remaining excess reactant, subtract the mass of excess reagent consumed from the total mass of excess reagent given.
We are given with
136 g P4
excess oxygen
The complete combustion reaction is
P4 + 5O2 => 2P2O5
Converting the amount of P4 to moles
136/123.9 = 1.098 moles
Using stoichiometry
moles P2O5 = 1.098 x 2 = 2.195 moles P2O5
Sulfur is the answer according to the 2'8-8 rule
