Xu is a new material discovered by a TA. The specific heat C and latent heat L of Xu are measured by heating up a piece of Xu sample. The above diagram shows the temperature T (in K) of Xu sample varying as a function of heat Q (in 103 J) transferred to it. (On the graph the heat added is cumulative: after a total of 6 x 103 J of heat are added the temperature is 400 K, after a total of 15 x 103 J of heat are added the temperature is 550 K, etc.) During the measurement the phase of the sample changes from solid to liquid, and then from liquid to gas. The mass of the sample is 10g.
What is the latent heat of vaporization of Xu in [J/kg]?