Water of volume 2 L in a closed container is heated with a coil of 1kW .While water is heated , the container loses energy at a rate of 160 J/s . In how much time will the temperature of water rise from $\;27^{0}C\;$ to $\;77^{0}C\;$ ? (Specific heat of water is 4.2 kJ/kg and that of the container is negligible) .