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How do you calculate the watts (joules/ second) of candle produced assuming a uniform...

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danielb77 | (Level 1) Valedictorian

Posted September 26, 2013 at 5:28 AM via web

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How do you calculate the watts (joules/ second) of candle produced assuming a uniform burn rate when the only information you have is the mass of water and aluminum can, specific heat capacity of water and aluminum, initial and final temperature of the calorimeter and mass of the paraffin burned. (A candle is heating up a can of water which is acting as a calorimeter).

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llltkl | College Teacher | (Level 3) Valedictorian

Posted September 26, 2013 at 6:08 AM (Answer #1)

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A candle is heating up a can of water which is acting as a calorimeter.

The amount of heat that is absorbed by the calorimeter can be obtained from the relation:

Heat absorbed, `H=H_1+H_2= m_1s_1Delta t+m_2s_2Delta t`

(where 1-terms refer to the aluminium calorimeter and 2- terms to the water in it, `Delta t` is the difference between final and initial temperatures of the calorimeter).

Total heat that is absorbed by the calorimeter is supplied by the burning candle/s. So, total heat, when divided by the mass of the paraffin gives heat obtainable from unit mass of paraffin.

To obtain wattage of burning of candles, rate of transfer of heat with respect to time is required. For this, idea of the time required to burn a candle completely (or a unit mass of it) is needed.

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