EASY
11th CBSE
IMPORTANT
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In an exothermic reaction, heat is evolved, and system loses heat to the surrounding. For such system

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Important Questions on Thermodynamics

MEDIUM
11th CBSE
IMPORTANT
The spontaneity means, having the potential to proceed without the assistance of external agency. The processes which occur spontaneously are
MEDIUM
11th CBSE
IMPORTANT
For an ideal gas, the work of reversible expansion under isothermal condition can be calculated by using the expression w = nRT ln VfVt. A sample containing 1.0 mol of an ideal gas is expanded isothermally and reversibly to ten times of its original volume, in two separate experiments. The expansion is carried out at 300 K and at 600 K respectively. Choose the correct option.
EASY
11th CBSE
IMPORTANT

Consider the following reaction between zinc and oxygen and choose the correct options out of the options given below : 

2 Zn s+O2 g 2 ZnO s ; H =  693.8 kJ mol-1.

MEDIUM
11th CBSE
IMPORTANT
18.0 g of water completely vapourises at 100°C and 1 bar pressure and the enthalpy change in the process is 40.79 kJ mol-1. What will be the enthalpy change for vapourizing two moles of water under the same conditions? What is the standard enthalpy of vapourization for water?              
 
EASY
11th CBSE
IMPORTANT
One mole of acetone requires less heat to vaporise than 1 mol of water. Which of the two liquids has higher enthalpy of vaporisation? 
MEDIUM
11th CBSE
IMPORTANT

Standard molar enthalpy of formation, f H is just a special case of enthalpy of reaction, r H. Is the r H for the following reaction same as f H? Give reason for your answer. 

CaOs + CO2g  CaCO3s; f H = 178.3 kJ mol-1

EASY
11th CBSE
IMPORTANT

The value of fH for NH3 is  91.8 kJ mol-1. Calculate the enthalpy change for the following reaction : 

2NH3(g)  N2(g) + 3H2(g)                                                      

EASY
11th CBSE
IMPORTANT
Enthalpy is an extensive property. In general, if enthalpy of an overall reaction AB along one route is rH and rH1, rH2, rH3 ..... represent enthalpies of intermediate reactions leading to product B. What will be the relation between rH for overall reaction and rH1 , rH2 ....., etc for intermediate reactions?