## Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)

$6900~J$ of heat energy must be added to the mercury.
The heat energy $Q$ required to change the temperature of a substance is: $Q = m~c~\Delta T$ The heat energy $Q$ required to change the state of a substance is: $Q = m~L$ We can find the heat energy required to change the mercury into mercury vapor. $Q = m~c~\Delta T + m~L$ $Q = (0.020~kg)(140~J/kg~C^{\circ})(357~^{\circ}C-20~^{\circ}C) + (0.020~kg)(2.96\times 10^5~J/kg)$ $Q = 6900~J$ $6900~J$ of heat energy must be added to the mercury.