new ,11 3:12 P.M Reasonable efficiency for converting chemical energy to electri

Question

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,11 3:12 P.M Reasonable efficiency for converting chemical energy to electrical energy via combustion is 30%. Calculate how many pounds of coal must be burned to run your reading lamp for two hours of studying for a chemistry exam. A typical reading lamP has a 75 W bulb. Assume that coal is pure graphite. (1 W = 1 J/s.) lbs 10 points Shutz E077,E01 ky Nolcs Ask Your Teacher Average daily calorie need is based on a resting metabolic rate for an average adult of 80 watts (1 W -1 J/s). How many calories per day must the average adult consume to maintain a resting rate? (One food calorie = one chemical kcal) food cal Vigorous exercise can raise the caloric requirement by a factor of 7.5. How many more calories are needed by a person who exercises 45 minutes each day? food cal

Explanation / Answer

Answer:

Energy required to get 75 Joules/sec of energy.

Burning of coal reaction.

C + O2 CO2

Durinng this reaction there relases approximately 2928.8 Joules of energy if it burns 1000 grams of Coal.

Then 75 Joules of energy will obtained from = (75*1000)/2828.8

Weight of coal = 25.60 grams

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