A cook wants to heat 1.10kg of water from 33 C to 100 C. If he uses the combustion of natural gas which is exothermic to heat the water, how much natural gas will he need to burn? Natural gas produces 49.3 kJ/gram.

Question

A cook wants to heat 1.10kg of water from 33 C to 100 C.  If he uses the combustion of natural gas which is exothermic to heat the water, how much natural gas will he need to burn?  Natural gas produces 49.3 kJ/gram.

Bob · Accepted Answer

6.8 grams

DrBob222 · Answer

How much energy do you need to heat the water? That is q = mass x specific heat x (Tfinal-Tinitial) = 1000 x 4.184 x (100-33) = approximately 310 kJ.
CH4 + 2O2 ==> CO2 + 2H2O + 49.3 kJ/gram
1 g x 310 kJ/49.3 kJ = grams