The mass of carbon anode consumed (giving only carbondioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is (Atomic mass Al= 27)
180 kg
270 kg
540 kg
90 kg
D.
90 kg
In Hall and Heroult process
2Al2O3 4Al + 3O2
4C + 3O2 2CO2 + 2CO
2Al2O3 + 4C 4Al + 2CO2 + 2CO
Only for removal of CO2, following equation is possible
2Al2O3 + 3C 4Al + 3CO2
Molecular weight of Carbon = 12
Molecular weight of Aluminium = 27
For Carbon/ C = 3 x 12 = 36
For Aluminium/ Al = 4 x 27 = 108
For 108 gm of Al, 36 gm of C is required in above reaction
For 270 gm of Al require amount of C =
The number of moles of KMnO4 reduced by one mole of KI in alkaline medium is
one-fifth
five
one
two
A reaction occurs spontaneously if
TS < H and both H and S are +ve
TS > H and both H and S are +ve
TS = H and both H and S are +ve
TS > H and H is +ve and S is - ve
The correct sequence of increasing covalent character is represented by
LiCl < NaCl < BeCl2
BeCl2 < NaCl < LiCl
NaCl < LiCl < BeCl2
BeCl2 < LiCl < NaCl
Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction?
Exothermic and decreasing disorder
Endothermic and increasing disorder
Exothermic and increasing disorder
Endothermic and decreasing disorder
A nuclide of an alkaline earth metal undergoes radioactive decay by emission of three -particles in succession. The group of the periodic table to which the resulting daughter element would belong to
Group 14
Group 16
Group 4
Group 6
The absolute enthalpy of neutralisation of the reaction
MgO(s) + 2HCl(aq) MgCl2(aq) + H2O(l)
will be
less than - 57.33 kJ mol-1
- 57.33 kJ mol-1
greater than-- 57.33 kJ mol-1
57.33 kJ mol-1
Equilibrium constants K1 and K2 for the following equilibria
NO (g) + NO2(g) and
2NO2(g) 2NO (g) + O2(g)
are related as