# the amount of energy released by burning a fuel source, measure in energy per mass, is called the fuel value.?

the amount of energy released by burning a fuel source, measure in energy per mass, is called the fuel value. if all the energy obtained from burning 1.24 pounds of methane (fuel value is 11.97 kcal/g) is used to heat 122.5 kg of water at an initial temperature of 20.5C what is the final temperature?.

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Don't you justs hate it when they mix up the units like that?

1.24 lbs = 562.45 g

So 562.45 x 11.97 kcal/g = 6732.53 kcal

6732.53 kcal = 28181.02 kJ

Now just go:

28181.02 kJ = 122.5 kg x 4.19 kJ/kgoC x Delta T

Delta t = 54.9 oC

so the water went up 54.9 degress to bring the final temp to 74.9 oC

• Francisca4 years agoReport

how did you get the 74.9 oC as the final temp

• 1.24 lb / 2.204 kg/lb = 0.563 kJ = 563 g

11.97 kcal/g X 563 g = 6734 kcal

6734 kcal = m c (T2-T1) = 122.6 kg X 1 kcal/kg X (T2-20.5)

T2 = 34.4 C

• Anonymous
5 years ago

ArtomR, Al divided 28181.02 kj by (122.5kg*4.19kj/oC), which gives you the 54.9.

• Al, how did you get delta T of 54.9