In one experiment, the temperature of 50 g of water increased from 22.0 °C to 38.4 °C. The mass of alcohol burned was 0.8 g. Calculate the heat energy (Q) in joules, released by burning 0.8 g of the alcohol.
Key Equation: Q = mcΔT Where: Q = heat transferred (J), m = mass of substance which is heated (g), c = heat capacity of water (J g-1 °C -1) and ΔT = temperature change for heated substance (°C) . c = 4.2 J g-1 °C -1 Heat energy is transferred to the water because alcohol burning releases heat. Hence, 'm' = the mass of the water heated. ΔT = 38.4 °C - 22.0 °C = 16.4 °C Substitute values into the Key Equation. I would recommend always including units in calculations, it will help us avoid errors. Q = 50 g x 4.2 J g-1 °C -1 x 16.4 °C = 3444 J
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