Answer
It will take $79.7~seconds$
Work Step by Step
We can find the amount of heat required to raise the temperature by $80.0~ C^{\circ}$:
$Q = m~c~\Delta T$
$Q = (0.50~kg)(4186~J/kg~C^{\circ})(80.0~C^{\circ})$
$Q = 1.6744\times 10^5~J$
The amount of heat required is $1.6744\times 10^5~J$
We can find the time required to provide this amount of heat:
$t = \frac{Q}{P} = \frac{1.6744\times 10^5~J}{2100~W} = 79.7~s$
It will take $79.7~seconds$.
