EASY
Earn 100

What is the enthalpy change for the given reaction if enthalpies of formation of Al2O3 and Fe2O3 are -1670 kJ mol-1 and -834 kJ mol-1 respectively ? Fe2O3+2AlAl2O3+2Fe

50% studentsanswered this correctly

Important Questions on Thermodynamics

HARD

An athlete is given 100 g of glucose C6H12O6 for energy. This is equivalent to 1800 kJ of energy. The 50% of this energy gained is utilized by the athlete for sports activities at the event. In order to avoid storage of energy, the weight of extra water he would need to perspire is _____g (Nearest integer) Assume that there is no other way of consuming stored energy.

Given : The enthalpy of evaporation of water is 45 kJ mol-1

Molar mass of C,H&O are $12.1$ and 16 g mol-1.

EASY
At 298 K, the enthalpy of fusion of a solid X is 2.8 kJ mol-1 and the enthalpy of vaporisation of the liquid X is 98.2 kJ mol-1. The enthalpy of sublimation of the substance X in kJ mol-1 is ______. (in nearest integer)
MEDIUM

The change in enthalpy ΔH in kJmol-1 for the reaction is Mg+2 FMgF2

Given: EA of F=328 kJ mol-1,IE1 of Mg=737 kJ mol-1,IE2 of Mg=1451 kJ mol-1

HARD
Enthalpy of fusion and enthalpy of vaporization for water respectively are 6.01 kJ mol-1 and 45.07 kJ mol-1 at 0°C what is enthalpy of sublimation at 0°C?
HARD
The heat of atomization of methane and ethane are 360 kJ mol-1 and 620 kJ mol-1, respectively. The longest wavelength of light capable of breaking the C-C bond is (Avogadro's number=6.023×1023, h=6.62×10-34 J s)
HARD

The Born-Haber cycle for KCl is evaluated with the following data:
ΔfHΘ for KCl=436.7kJmol1;ΔsubHΘ for K=89.2kJmol1;

Δionization HΘ for K=419.0kJ mol 1;Δelectron gain HΘ for Cl(g)=348.6kJmol1

Δbond HΘ for Cl2=243.0kJmol1
The magnitude of lattice enthalpy of KCl in kJmol-1 is (Nearest integer)

MEDIUM
If enthalpy of atomization for Br2(l) is kJ/mol and bond enthalpy for Br2 is kJ/mol, the relation between them
MEDIUM
The elements with the highest and the lowest enthalpy of atomisation respectively, for first row transition elements are:
HARD

For one mole of NaCl(s) the lattice enthalpy is

Na(s)+12Cl2g+108.4 kJ/molNa(s)+12Cl2g+495.6 kJ/molNa(g)++12Cl2g121 kJ/mol

Na(g)++Clg-348.6 kJ/molNa(g)++Cl(g)-ΔH0 altice Nacl (solid) -411.2 kJ/molNa(s)+12Cl2g

HARD

The standard enthalpies of formation of CO2(g) ,H2Ol and glucose (s) at 2 5 o C are  - 400 kJ / mol , - 300 kJ / mol and - 1300 kJ / mol , respectively. The standard enthalpy combustion per gram of glucose at 2 5 o C is 

(ΔHf0=1300kJmol1 for Glucose)

MEDIUM
Enthalpy of sublimation of iodine is 24 cal g-1 at  200°C . If specific heat of I2 (s) and I2 (vap) are 0.055 and 0.031 cal g-1K-1 respectively, then enthalpy of sublimation of iodine at 250°C in cal g-1 is:
MEDIUM
The combustion of benzene l gives CO2g and H2Ol. Given that heat of combustion of benzene at constant volume is -3263.9 kJ mol-1 at 25°C; the heat of combustion in kJ mol-1 of benzene at constant pressure will be

R=8.314 JK-1 mol-1
EASY
The heat of combustion of carbon to CO2 is -393.5 kJ/mol. The heat released upon the formation of 35.2 g of CO2 from carbon and oxygen gas is
MEDIUM
The heats of combustion of carbon and carbon monoxide are -393.5 and-283.5 kJ mol-1, respectively. The heat of formation in kJ of carbon monoxide per mole is:
HARD
The enthalpies of formation of CO(g),CO2( g) and N2O(g) are -110,-393 and 81 kJ mol-1 respectively. If the enthalpy of reaction ΔrH for N2O4( g)+3CO(g)N2O(g)+3CO2( g) is -778 kJ, the enthalpy of formation of N2O4( g) in kJmol-1 is
MEDIUM
Enthalpy of combustion of methane and ethane are -210 k cal/mol and -368 k cal/mol respectively. The enthalpy of combustion of decane is
MEDIUM
The ionization enthalpy of Na+ formation from Nag is 495.8 kJ mol-1, while the electron gain enthalpy of Br is -325.0 kJ mol-1. Given the lattice enthalpy of NaBr is -728.4 kJ mol -1 . The energy for the formation of NaBr ionic solid is -_____10-1 kJ mol-1
MEDIUM
Lattice enthalpy and enthalpy of solution of NaCl are 788kJmol-1and  4kJmol -1, respectively. The hydration enthalpy of NaCl is:
 
EASY
The enthalpy change on freezing of 1 mol of water at 5°C to ice at -5°C is:

(Given Δfus H=6 kJ mol-1 at 0°C,

CpH2O, l=75.3 J mol-1K-1

CpH2O, s=36.8 J mol-1K-1 )