Question
In grinding a steelknife blade (specific heat = 0.11 cal/g- C), the metal can get ashot as 400 degrees celcius. If the blade has a mass of 80 g, whatis the minimum amount of water needed at 20 degrees celcius if thewater is not to rise above the boiling point when the hot blade isquenched in it? The answer is 33 g. Please explain. In grinding a steelknife blade (specific heat = 0.11 cal/g- C), the metal can get ashot as 400 degrees celcius. If the blade has a mass of 80 g, whatis the minimum amount of water needed at 20 degrees celcius if thewater is not to rise above the boiling point when the hot blade isquenched in it? The answer is 33 g. Please explain. The answer is 33 g. Please explain.
Explanation / Answer
. Specificof steel, Cs = 0.11 cal/g.oC . Fall intemperature of knife blade, t1 = 400 - 100 . = 300 oC . Mass ofthe blade, M1 = 80 g . Specific heatof water, Cw = 1 cal / g.oC . Raise oftemperature of water, t2 = 100 - 20 . = 80 oC . Fromthe principle of calorimetry, . Heat gained by water = Heat lost by steel blade . M2Cw t2 = M1 Cs t1 . M2* 1 * 80 = 80 *0.11 *300 . Mass of water, M2 = 33 g