How do I answer this ?
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"What are the recent changes I've noticed on Socratic?"
Look at the 10 minutes to bring the water to boiling. That required a temperature change of #80^@ K#.
The specific heat is #4.2 kJ*kg^-1*K^-1#
So let's multiply those 2 factors together
#(4.2 kJ*kg^-1*cancel(K^-1))*(80^@ cancel(K)) = 336 kJ*kg^-1#
That is a result that gives us an idea of the immersion heater's rate of producing heat and the affect of this amount of water. How big a job is getting the water to evaporate compared to heating it to the boiling point?
Notice that the #336 kJ*kg^-1# result we just got has the same units as #2268 kJ*kg^-1#, the specific latent heat of steam. Therefore, we can calculate the ratio by which getting the water to evaporate is a larger job than heating it to the boiling point.
#(2268 kJ * kg^-1)/(336 kJ * kg^-1) = 6.75#
Since the job that gave us the #336 kJ*kg^-1# result required 10 minutes, we need to multiply that last number by 10 minutes.
#10 "minutes" * 6.75 = 67.5 "minutes"#
I hope this helps,
Steve
