In a hydrogen-oxygen fuel cell, combustion of hydrogen occurs to
generate heat
create potential difference between the two electrodes
produce high purity water
remove adsorbed oxygen from electrode surfaces
The compound that can work both as an oxidising as well as reducing agent is
KMnO2
H2O2
Fe2(SO4)3
K2Cr2O7
Which one of the following is not a method to remove permanent hardness of water?
Clark's method
Calgon method
Ion- exchange method
Synthetic resins methods
Reaction of calgon with hard water containing Ca2+ ions produce
[Na2CaP6O18]2-
CaCO3
CaSO4
Ca2(PO4)3
A.
[Na2CaP6O18]2-
Calgon is a trade name of complex salt, sodium hexametaphosphate (NaPO3)6. Calgon ionises to give a complex anion. The addition of calgon to hard water causes the calcium ions of hard water to displace sodium ions from the anion of calgon and form a complex with calgon.
Diborane (B2H6) reacts independently with O2 and H2O to produce, respectively:
B2O3 and H3BO3
H3BO3 and B2O3
B2O3 and [BH4]-
HBO2 and H3BO3