At a 62% heating efficiency, determine the quantity of natural gas, in g, required to melt 25g of solid gold, initial temperature is 20 degrees celsius, to produce molten goldat 1850 degrees celsius.
Cs gold = 0.032 cal/gC
Cl gold = 0.036 cal/g C
Lf gold = 15.8 cal/g
Lv gold = 406.4 cal/g
Tm gold = 1064 C
Lc, natural gas = 8.40 x 103 cal/g