Short Answer TypeCompute internal energy change of a system if it
(i)Â absorbs 500 kJ heat and does 300 kJ work.
(ii)Â loses 200 kJ heat and has 450 kJ of work done on it.
A sample of gas is compressed by an average pressure of 0.50 bar so as to decrease its volume from 450 cm3Â to 250 cm3. During the process 6.00 J of heat flows out to surroundings. Calculate the change in internal energy of the system.
State whether each of the following will increase or decrease the total energy content of the system:
(i) heat transferred to the surroundings
(ii)Â work done on the system
(iii) work done by the system.
Long Answer Type
Under what conditions
(i)∆H < ∆U
(ii) ∆H > ∆U
(iii) ∆H = ∆U?
We know that ∆H = ∆U + ∆ng RT where ∆ng represents the difference between the number of moles of the gaseous products and of gaseous reactants.Â
(i) ∆H < ∆U
When ∆ng = –ve i.e. when there is a decrease in the number of moles of the gaseous components.
  
 
when ∆ng = + ve i.e. when the reaction proceeds by an increase in the number of moles of the gaseous components.
   
(iii) ∆ng = 0 i.e. when the number of moles or the gaseous reactants is equal to the number of moles of the gaseous products.
         
          
       
Short Answer Type
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