how many ml of a 22.5% (v/v) ethanol solution would you need to measure out in order to have 12.5 ml of ethanol ?
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Answer:
The correct answer is 333.8 J
Explanation:
Ice (water in solid state) melts at 273 K (0ºC). During the phase change from solid to liquid, water absorbs 6.01 KJ per mol until it melts completely. To calculate the heat absorbed, we first have to convert the mass of water (1 g) to mol by using the molecular weight of water (H₂O):
Molecular weight of water= 2 x molar mass H + 1 x molar mass O
Molecular weight of water= 2 x 1 g/mol + 16 g/mol= 18 g/mol
mol ice= = 0.055 mol
heat= 0.055 mol x 6.01 KJ/mol= 0.3338 KJ
Finally, we convert KJ to J (1 KJ= 1000 J so we multiply by 1000):
0.3338 KJ x 1000 J/1 KJ= 333.8 J