Question

Under what condition reversible process become irreversible?

Answer 1

generally in a reversible process one of the product is in gaseous state so in case of taking a closed vessel if you take an open vessel then the gaseous product escapes and then the reversible process becomes irreversible.If there is no gaseous product then reversible process becomes irreversible in to conditions 
1.)If you are removing the products continuously 
2.)If you are adding reactants continuously


The process become irreversible if G is +.so by increasing H i.e enthalpy ,decreasing T temp ,S random