How many grams of alcohol must be burned in order to change the temperature of water weighing 8 kg
| March 19, 2021 | education
How many grams of alcohol must be burned in order to change the temperature of water weighing 8 kg from 14 to 50 degrees C, if all the heat released during combustion goes to heating the water.
To calculate the mass of alcohol consumed, we use the equality: qc * mc = Q (heat for heating water) = Cw * mw * (t2 – t1), whence we express: mc = Cw * mw * (t2 – t1) / qc.
Constants and variables: Cv – beats. heat capacity of water (Sv = 4200 J / (kg * K)); m is the mass of heated water (mw = 8 kg); t2 – final temperature (t2 = 50 ºС); t1 – temperature before heating (t1 = 14 ºС); qc – beats. the heat of combustion of alcohol (qc = 2.7 * 10 ^ 7 J / kg).
Calculation: ms = 4200 * 8 * (50 – 14) / (2.7 * 10 ^ 7) = 44.8 g ≈ 45.
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