One kg of an ideal gas (gas constant $R= 287\: J/kg.K$) undergoes an irreversible process from state-$1$ ($1$ bar, $300 \: K$) to state-$2$ ($2$ bar, $300\: K$). The change in specific entropy $(s_{2} - s_{1})$ of the gas (in $J/kg.K$) in the process is _________.