function state2 = getStateAfterIsobaricProcess(state1, state2, gas)
  V = getVname(state1) ;
  equation.variableNames = [ "T" V "const"] ;
  equation.exponents     = [  1 -1   -1   ] ;
  variableName = getUnknownVariableNameFromConstEquation(state2, equation) ;
  state2 = updateStateFromConstEquation(variableName, state1, state2, equation) ;
  state2.p = getVariableFromStateEquation("p", state2, gas) ;
end